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Decisions and Decision Making This chapter is land and it has been split into three parts. You are now in Part 1. You may go to Part 2 or to Part 3.
I worked for many years on a systems approach to wildlife management and assumed that most of the concepts of population and habitat management were concepts that could be called system processes. I had jumped too quickly to the animals and their homes. This is a book about decisions, not about animals. It is about resource management, not animal biology or ecological complexities. There is a need to understand the decision process itself and to understand it well, for then it can be applied to the old as well as not-yet-conceived aspects of this dynamic field. I knew that wildlife management was primarily decision making and then I realized that I had not addressed it specifically. I treated the parts of the system, chapter by chapter, but omitted "processes."
I remember the day that I read that statistics was for decision making. Of course!, and since wildlife management is decision making, a primary tool is statistics. Somehow that viewpoint had been lost to me (and many of my students) among the topics of data, esoteric symbols, and the need, it seemed, for squaring everything. I can only continue to encourage involvement in learning more of that broad field. There are other aspects of decision making that can be learned. It is not a mystical art form.
Decisions are little systems. You take a systems approach to decisions. You analyze them as systems and use the parts, with their techniques, to improve outcomes. The people recognized as good decision makers are those who have a pattern in their decision making activity. Odds are that the pattern will be easily analyzed as being like a "systems approach."
Most faunal system decisions are difficult. They have evident conflicts. Something that improves conditions for species x degrades the conditions for species y. What shall I do? Decisions in this field are not only difficult because they are complex (ecologically, energetically, economically, esthetically) but because they place the decision maker in a special social environment. They allow people to name the decision maker, to allow him or her to be classified. This is one of the consequences of non-trivial decisions (like deciding to get a glass of water or not). That decision making has costs and risks cannot be ignored. It is the chief reason why people are paid. The higher the risks, the higher the rewards.
In public agencies, the concept of the responsible decision maker slips away as more decisions seem to be made by committees and boards. Decisions are made by a person in an instant (no matter how long the decision making system has taken). Fixing responsibility, naming the person who will receive the praise or the blame (the profits or the losses) for the decision, is part of defining the system context, of naming the subsystem.
Some people start analyzing situations in which a decision seems needed and assert that the problem has to be identified. My analyses suggest that a problem is seen in the difference between objectives and the current situation. (I described that difference, the gap, in Chapter 4.) To improve decisions:
There is a tendency to list only three alternatives. How three became the standard, I know not! In many situations, I have found that forcing myself to seek out a fourth alternative (one for another vertex of the tetrahedron) has provided important insights and advantages. Realize too, that the computer can evaluate thousands of large and complex alternatives rapidly. To surrender to "three" almost assures that the best one available (somewhere) is not selected.
Information on possible secondary and cumulative effects is part of this input part of the decision system. It also includes listing the alternatives. The public, general advisors, and local experienced people can aid in producing this list.
"Sure" is an expression of risk, (i.e., 1.0 - the probability of failure).
All decisions are made with an element of risk; there is no certainty (I shall not discuss religious certainty). There are risks of physical system failure such as floods, storms, insect attack, and simple failure to perform as expected (as from fertilization or when a new variety of plant is tried on an area.) There are harvest failures (e.g., hunting success), social disruption (e.g., unseen secondary consequences of a road crossing, providing road access, or changing a season), and personal risks (e.g., reputation, promotion, opportunities for later tasks). In the private sector, risks can be tallied as direct loss of investment dollars. Accounting risks within public agencies is more subjective but needs to be done. Estimates need to be attempted.
Use expected value as described in Chapter 4. Multiple the best estimate of the likely consequence(s) by (1.0-risk) (resulting in the expected value and select the alternative with the highest value. The value is not "real"; it is a bunch of estimates, aids to making decisions. The value is a guide, not the decision it self. There are likely to be other things that say the alternative with the highest expected value is the wrong one to select. If so, explain why, insert the reason as an objective (something to be avoided) and start the procedure over again at a reasonable point.
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| Watersheds are unique. High variance prevents adequate sample sizes for such areas. Alternative strategies are needed. |
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| Fig. 7.1. The manager exists in the force-field created by the interplay of three factors that are decided. Efforts to move as far away as possible from a zero value are opposed by time, available funds, tendencies to increase variance, needs for equipment, trained personnel and the difficulties of analyzing and communicating the results. |
As you read further, you may want to return to a place in the text well past this place in the unit. Ignore this statement for now; click on it later to return easily and quickly to a place later in the text.
The proper location in this tetrahedral space is partially the manager's decision, partially dependent upon what administrators have been taught, what reviewers expect in journal reports, and, as always, available time, technology, and budgets. Precision is the category for measurement devices and metrics. The use of a millimeter rule is possible for measuring an area boundary; so is pacing. The ruler is very precise; pacing very gross or imprecise. The manager needs to decide.
Max and Snellgrove (1952) commented that the consequences of choosing a precision level for measurement can be critical. If too high, measurements may be too costly and time consuming to make. (See also Hamilton 1979.) If too low, very imprecise measurements may result in variability that contributes to the overall expression of error in statistical analyses.They observed that levels based on experience can stand questioning and new problems arise for which there is no experience. They presented a method - an analysis of the contribution of the maximum measurement error to the maximum total error - for selecting a level of precision. However, even it requires subjective comparisons of the resulting ratios.
A poorly trained or disinterested field assistant may not make measurements very accurately, no matter what unit is selected. Accuracy expresses the difference between the true measure and that observed and reported. A well-intentioned observer may be biased for many reasons. Bias may be purposeful (an observer wanting to "show something" like there not being enough forage for a species or there being too many resource users). Bias does not need to be purposeful. An instrument may malfunction at some levels, an observer's sight or hearing may not be appropriate for the assigned tasks, instructions may not have been understood, or there may be misperception (as in optical illusions). Estimating the percent covered by vegetation in a square plot is a typical situation where bias is frequent. It can be "trained away" but frequently it is as useful to determine what the bias is (e.g., by having the observer look at 30 plots of known percent coverage). He or she may report what was observed. A comparison is made and, for example, they consistently report 0.93 of the true coverage. Then all of their field work is divided by 0.93 to bring it to the true value. Whether being 0.93 from the true value is too inaccurate is a decision for the manager. It depends ... on many factors. "Close enough" is a frequently heard expression.
Habitat or Faunal Space
"Habitat" is no longer a useful word in faunal system management (Moen 1973, Coulombe 1978, Hoover and Wills 1987, Harris and Kangas 1988). An animal is inseparable from its surrounding. A toxic molecule in a lung - is it inside the animal or in its environment? The moisture in a cell of an animal's nose - inside or out? The union of a frog or earthworm with its over-wintering conditions suggests that all is one. Habitat, niche, community - landscape, management area, forest - all are discussed and debated because of confusion in meaning, ignorance of or unwillingness to accept first-use definitions, unwillingness to move to common terminology and to develop alternative taxonomy as new knowledge suggests meaningful change.
There are multiple meanings and assumptions about"habitat" and whether it expresses (1) individual, population, or species assemblage needs; (2) differences in seasonal and migratory needs; (3) fundamental requirements or their associates; (4) needs in disjunct areas, or (5) whether the animals themselves are considered habitat. In the landscape ecology sense (Rodiek and Bolen 1990), all factors may be present for"good" habitat for a life group, but the size of the area or its nearness to other areas may be inadequate. Nearness to a large suitable area may make a"bad" area capable of supporting a population. "Habitat" is too elastic. Coulombe (1978) found four themes for the concept: (1) life requirements for single species or life groups, (2) resource allocation between or within species (as in"partitioning"), (3) spatial distributions and types (as in"nesting"), and (4) quality for a species or group. He noted that"habitat" rarely related to scale since that for an organism could be described as (a) being the bark of trees in general, or that (b) of a tree species, (c) of a mountain ravine, (d) of a topographic zone, (e) of many spaces (as for migrants), or (f) of a biome.
A replacement of the word is needed. To improve the health or well-being of an individual animal, you hire a sensitive veterinarian. To improve on the well-being of a population of animals you hire a sensitive modern forester or faunal system manager. Rarely does the forest faunal manager deal with individual animals, only the population, and usually by manipulating where it exists. The forest is a very complex and complicated place and the manager must master the complexity of this place.
"Habitat" has its roots in"home" and thus is misleading as the basis for a viable full-scale management system that deals with animals that migrate, and that are influenced by global changes. The habitat of many animals is faunal (microorganism of a wide range, parasites, and other animals, predators, nest mates, and pack and herd associates) as well as flora. I find feathers or the outer 2 centimeters of hair very"habitat like" but yield reluctantly to convention; these are a part of animal studies, rarely of habitat. Rather than habitat, the"faunal surround" or"faunal space" are useful phrases, implying the outside-of-the-animal environment - everything.
The forest faunal system manager creates and maintains space for animal populations and for users of these populations. A hunting"area" is managed for animals (usually to increase them) but also for users so that animals produced may be hunted or otherwise used in ways to maximize benefits. The resource system manager does not manage"animal homes," except at personal risk of mismanagement. Management is of spaces for desired populations and their legal users. It is available forage and protection from energy loss; legal protection; adjacent animals hiding places; special landscape patterns; and species-specific seasonal provisions. Habitat is a word which readers may lay aside for use only in general discussions.
There are few topics more difficult to discuss than the spaces for forest wildlife. There are so many species and life groups, so many biomes, so many different requirements of each life group, so many techniques (Thomas 1979, Cooperrider et al. 1986, Bonham 1989, DeGraaf et al. 1989, Patton, 1992) and, if those were not enough reasons for the difficulty, then there can be added the potential conflicts between tree cutters and people with a wildlife interest. Resolving or easing these difficulties is possible, but it is very hard work. Knowing that there are long-standing, deep-seated disagreements, and that resolution is hard work may help reduce the frustrations and inspire concerted effort for people of the forested world ahead. McAtee (1936) of the Bureau of Biological Survey that preceded the U.S. Fish and Wildlife Service said they had "...signed a truce with the Forest Service that neither will criticize the other publicly." But he was speaking of his experience that "...indicates that difficulties are likely to arise in combining forest management and wildlife management on the same area." He went so far as to suggest the option that the two should "...'agree to disagree' and plan for substantial or complete separation of their spheres of activity." He made a remarkable statement for its date, 1936:
As has been shown in the preceding discussion, however, stand improvement practice steadily diminishes the value of forests for wildlife and maintenance of the closed canopy virtually destroys it. This is so obviously the case that authorities freely assert that the interior of a dense forest is practically barren of wildlife. The reputation of our forest reserves as wildlife producers is really due chiefly to their un-forested portions, to open glades and parks, to brushlands and slashings, to cut-over tracts, and to burns. When, therefore, we speak of forested areas as the home and creative center of wildlife, we are using a figure of speech and we could more literally and truthfully say that they are the conservators and the source of wildlife about in proportion to their departure from the standards of an ideal forest. Departing from those standards is a necessity for attaining any considerable degree of coordination with worthwhile policies of wildlife management. In this country, forestry, and its practices are established while real wildlife management is an innovation. Necessarily, therefore, concessions essential to good coordination of forestry and wildlife management must come from the forestry side. The fact certainly is clear that if we sincerely wish to favor wildlife in forest reserves, we must curb the universal growth of trees, we must preserve openings of varied types, and liberally foster brushland vegetation.Immediately looms the specter of 'highest use' and if that use irrevocably is decided to be timber production, then we must seek other reasons for wildlife production. Forests and foresters must be supplemented by coverts and keepers. Where the production of wildlife is accepted as the primary objective, it is futile, nay it is fatal, to adopt standard forestry practices, as in the long run they do not favor, but on the contrary definitely discourage, achieving specific faunal populations.
Many, probably most, foresters desire to favor wildlife so far as may be practicable, but both forest growth and forestry practice of the first class limit their opportunities. In fact wildlife must ever be a by-product on areas primarily devoted to growing timber. It is well for wildlife managers to take these facts into consideration and make necessary allowances. On the other hand when in charge of projects, the prime purpose of which is wildlife production, they should avoid trying to combine forest and wildlife management, but forestry precepts to the contrary notwithstanding, they should firmly put into practice any and all policies necessary for the highest welfare of wildlife. It is to be hoped that such ranges will increase rapidly in number and area so that wildlife shall at last receive the recognition so desperately needed and to which for a long time it has been fully entitled (McAtee 1936:422-423).
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| Moose on Wyoming winter range. Moose, elk, and deer move out of the high-elevation, deep-snow areas and forage on shrubs. |
The big game has an abundance of summer range within the forests, but the year-long problem brings into the picture the ever-troublesome question of winter range. Only 6 percent of the winter game range is within the national forest boundaries, the other 94 percent is mostly privately owned lands along with a small amount of public domain and is generally overused by domestic stock. This winter range situation controls the numbers and distribution of big game, especially in the case of deer ...
In southern Idaho the public demand has resulted in an expensive although inadequate feeding program, especially in the case of deer herds and to a lesser degree for a few isolated elk herds.
It is evident that feeding of these game animals cannot be continued indefinitely. The more feeding is practiced the more certainly do these game animals return to these areas for winter feeding. This revolving process, if continued, will produce more and more game, and although game may find ample summer forage, the winter ranges rapidly deteriorate and eventually become so reduced in carrying capacity that destruction of the game herds result. I will admit that this is an argument against winter feeding. I believe feeding should not be done except in unusual emergency conditions. Certainly we should so manage our game that a herd can be stabilized in numbers to meet the ability of the winter range to carry them safely. This can be done only by a well-planned program of management based upon all of the facts bearing on each local problem and by unified action of all cooperating agencies backed by the support of an informed and interested public.
Another of our major problems in southern Idaho is the existence of extremely large game preserves established by the State legislature. In some instances these preserves include a large part of individual national forests. The enactment creating these preserves made no provision for managing the game within them and has resulted in creating a serious problem which is detrimental to the game and is resulting in injury instead of benefit.
One specific case is the South Fork of the Payette River game range for 1,000 deer, 1,000 elk, and 500 mountain goat; it now has 4,000 deer, 600 elk, and 250 goat. This has created a huge over-population of game which is in excess of, and has materially reduced, the carrying capacity of the inadequate winter range within the preserve. Where possible the game has overflowed into the only other available winter game range, namely, privately owned lands.
Due to the climatic conditions, migration from the game preserve to the winter range does not take place until mid-winter. The regular open season provided by the state game laws closes prior to the usual migration of the game from the preserve boundaries and consequently systematic reduction of the herd is not possible. One year out of every five, when the weather conditions are severe during the hunting season, the deer are slaughtered. As much as 50 percent of the herd has been killed during one season. On the other hand, for several average years the annual kill has not exceeded 10 percent.
Game simply cannot be properly managed under such conditions, and it is imperative that every interested organization and sportsman direct constant effort toward early legislative action which will make it possible to manage game properly.
The recent establishment of extensive primitive areas is another complication. Because of the few roads into such areas, hunting is of little importance as a means of controlling the harvest of game. The game herds actually increase toward a maximum in numbers. We can anticipate overpopulation, resulting in overuse of the available winter range within the next decade, unless some method of control is developed in the near future ...
We realize that there is a real problem in connection with our furbearers and that we have very inadequate information upon which to base any corrective action.
More study, planning and positive action must be taken in handling our mountain sheep, mountain goats, and remaining antelope herds ...
All of these problems become the more acute when it is realized that the largest human population centers of the State are in many cases immediately adjacent to the winter ranges as well as the summer ranges. During the winter period thousands of people visit the game herds and quite naturally raise a cry for more and more feeding, because of the inevitable presence of a few starving deer or elk.
There is always a demand for more game production but no thought of how to produce and maintain it. The first thought of 'John Citizen' seems to be more protection. In fact, it might be said that in many cases we are preserving our game that it may starve. One of the most needed things at the present time is a state game law under which it would be possible to take prompt action in managing all game wherever the need arises. Most certainly we wish to produce more game, but before we do so we must provide for its maintenance, and in the meantime we must properly provide for and manage what we now have (Varner 1938:9-11).
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| Ancient big game migration routes are blocked or range innundated by hydro-energy or irrigation projects. Winter range (often no more than 10% of the area once used by animals) is otherwise destroyed by human developments or otherwise made unsuitable by human presence in the lowlands |
There have been changes, though, since the 1930's in knowledge of faunal spaces and how they can be managed. The evidence is that knowledge per se is not what allows or causes the changes in the forest. The essentials are: knowing what is desired, what to do, why, doing something, then how to explain actions and their reasons, and then how to stabilize or enforce the actions.
The manager working with specific animal groups will often develop personal guides for analyzing areas and animals. For example, someone may use the guide of 2.5 kilograms of forage needed per day per 50 kilograms of herbivore (e.g., deer). This varies with season, dryness of forage, whether the animals are lactating, etc. It is a gross guide, a way of thinking quickly about what is generally needed by a large population. For example, for 2000 animals each weighing about 50 kg, the manager must supply 1,825,000 kilograms of forage. By knowing home range sizes (grossly), estimates can be made of how the forage must be distributed. If we use a clipper to sample forage and discover an average of 300 kg of forage per hectare, we had better have 6100 hectares like it to feed the 2000 animals. If the population has been stable at 2000 and we have more than 6100 hectares, then we can estimate the amount of unproductive land or estimate the losses due to poaching, predators, disease, etc. The usual assumption accompanying such gross analyses is that animals and plants will fill an environment, use every available resource to its limit. These are rough calculations and assumptions that are occasionally useful in the field. They need to be brought into the lab for careful thought, computer work, and detailed local observations and analyses. Before that, however, the decision maker, this manipulator of the faunal system, must understand the system context. Not some plea for an academic exercise, this understanding reduces frustrations, wasted effort, and suppressed projects; it may reduce sample sizes and costs because it allows meaningful assessment of desired confidence and accuracy. The understanding invariably improves communication about events which are often perceived as if they were people passing in dark agency halls after a power failure. It prevents direct violation of policy and law. It allows team efforts, i.e., many managers and owners, over many areas, to engage in loose coalitions to best an opponent (Chapter 17).
The subject of faunal spaces is very large, the entire"forest" of forest faunal systems. Topics are interrelated. I start, suboptimally, with "history."
Vegetation History
I think a faunal system person must know "inside and out" (implying"past and future") the environment within which work is to be done. The past should include plate tectonics and the location of the management area relative to the equator in pre-history (Vermeij 1987). This knowledge, delightful unto itself, is potentially useful in explaining the paleoecology of an area, interpreting and protecting fossil evidence, and developing theories of modern geobotany and how they may help improve predictions about vegetation on the area.
Persistent Pleistocene and pre-Pleistocene environments are exciting places. Sometimes called relict communities, these areas are valuable for their special flora and fauna and their role in adding faunal richness to the larger, more modern communities within which they are located. Special places, they deserve attention, but like threatened and endangered species, they are jewels. Like jewels, they are important in a household, but the tasks of paying the rent and putting out the garbage are the on-going and overpowering topics of household concern. They, like jewels, have high security costs. The management of millions of hectares of other wildlife areas, the non-relics, is the overpowering topic for the faunal resource manager.
Recent vegetation history provides insight to the past system dynamics, particularly limits to production and production rates. Post- Pleistocene changes, say the past 10,000 years in the U.S., are suggestive of the sources, dynamics, and potentials of the present environment.
In the eastern U.S., the American chestnut (Castanea dentata) has been nearly exterminated by the fungus Cryphonectria parasitica (Murr.) Barr (formerly Endothia parasitica). Vast forests were composed of 30% or more of chestnut and now that tree is gone. The forests have restructured. The enormous food supply of nuts supplied by these trees is no longer present. The net change in hard mast, in replacing chestnuts with acorns and hickory (Carya) nuts, is not known. (The lack of knowledge suggests studies needed now to answer similar future questions.) Chestnuts flower after any danger of frost, thus these trees provided a relatively stable hard-mast supply, unlike their replacements, the oaks and hickories, that have mast crops that are largely dependent on spring climatic conditions ( Diamond et. al 2000).
The faunal manager will master the historical changes as much as possible. Art work, old maps, conversations with older people, old photographs, diaries, and publications are essential materials for understanding the past. Oral recordings are very useful, especially if keyed to animals that indicate successional stages, to production (as honey from bees, mast from trees), and to indicator plants (showing pictures, not asking names). Much other landscape history can be read using the techniques listed in Table 7.1.
| Table 7.1. Techniques of landscape interpretation to discover the age and dynamics of ecosystems |
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1. Geology: Geological maps and site inspections for fossils, strata, etc. 2. Readings: Paleobotany and paleoecology sources 3. Topography: Inference about climate and vegetation from slopes, aspect, colluvial depth, land forms, and waterways 4. Radio-carbon Dating: Also related isotope and chemical dating 5. Pollen Analyses: Samples taken from bog cores to indicate species present and changes 6. Pre-settlement Human Site Studies: An animal's remains that are present in Indian middens imply requisite habitats 7. Soil Pit Layers: soil pits may reflect root penetration, root remains, layering, floods, etc. 8. Soil: Texture, color, and organic matter content may be studied relative to present vegetation 9. Rock and Surface Materials: Rock and soil particle size and thus water forces, depths, and salinity needed to move them 10. Deeds and Land Survey Descriptions: Corner trees and witness trees are frequently identified. Entire areas have been vegetatively mapped from such deeds 11. Dendrochronology: Growth rates of tree rings (standing trees and logs in historic buildings and bridges). Years of rain, drought, or insect attack. Time of fire scars in borings of the boles or tree stump observation. The technique is generally useful to about 11 A.D. Match rings in the field to those in wooden beams in dated (cornerstone) houses or churches 12. Plant Age: Mean age and age distribution of trees. Singular ages reflect cataclysmic events such as fires, storms. Succession and forestry curves enable retrospective and predictive vegetative analyses 13. Relict Study: Distribution and description of relict communities; interpretation of past climate 14. Trails: Paths of grazing animals on hillsides and depth of compaction or erosion 15. Plant Density: Density and distribution of trees. Reflecting forestry, stand manipulation, grazing, and fire 16. Lichen: Lichen bands at the base of large rocks or tombstones display rate of erosion 17. Erosion Lines: Erosion and lichen bands dated at the base of tombstones and along brick or concrete walls or walkways provide basic data on soil loss and surface change 18. Fire: Fire scars on trees and rocks; charcoal in alluvial soil layers 19. Plow Lines: Plow strata (as a sign of whether cultivated or not and for how long) can be read in soil pits and transects 20. Mammals: Mammal activity in the past can be read from relict soil burrows. The burrow size and pattern will determine the mammal and thus the requisite associated habitat 21. Birds: Lines of trees (having originated from birds defecating seeds while sitting on fences) display old field borders 22. Fence Lines: Field size, erosion rates, and cultivation can be read from lower-side fence rows which serve as a soil catchment. Fence posts may be buried, preserved, and available for analysis. Seasonal layers in a cross section of this soil hump may enable the duration of cultivation to be determined. Trees in fence rows may be aged to confirm fence dates 23. Buried Flora: Soil at old dikes and land fills may cover the original flora. |
Diamond (1988)"proved" the importance of ecological history to the faunal system manager. I believe such managers will want to use history to establish for their areas statements like:
This community has persisted over ___ years. About ___ years ago there were changes that resulted in a transition from A-type community to the present X-type. We can expect this stage to appear only ___ times in 200 years. We can only expect the present community for several hundred years (your great grandchildren's environment). We saw the loss of X and Y and we cannot describe significant differences in the community before and after those losses. Species Y has lived here for ___ years, surviving every high and low of environmental factor X1 to Xn. The rates of loss (or gains) have been ______ for over 500 years and we see no reasons to suspect change in the rate for the next 50 years.
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| Fig. 7.1. A time line for a faunal management area displays time as distance between points. |
CAP83 provides a professional time line to aid managers in comparing the rate of change in known time to change in planned time.
The community is the result of biota invading or remaining in an area; it is what the existing forest trees or environmental components like soil and precipitation "allow" to be present. The analyses of communities usually start with the dominants. Analyses, however, need to start with what once was, then advance to the present condition. Neither approach is easy; the preferred alternative is the one that makes more ecological sense, less statistical sense (thus one usually less tractable).
The need for permanent plots and permanent picture points can hardly be stressed enough. The costs are great, vandalism and losses high, and difficulties in managing records almost insurmountable. The difficulties do not deny the needs and a planned, coordinated effort to manage such information, at least regionally, at least as a viable museum and library function, need be debated no longer (Curtis 1983, Brewer and Barrier 1984).
Wilderness or natural areas are invaluable in establishing a dynamic, cumulative record of the past. Sections of faunal management areas should be"set aside," in fact"created," as any other positive managerial action, for the purpose of historical understanding. Fenced exclosures may suffice in some areas, but areas of at least a hectare should be marked and excluded from use except for making measurements. Larger areas are of equal or more importance because within them are opportunities for holistic communities developing.
Exclosures, even though expensive to construct and maintain, have been used extensively in wildlife studies, mostly to study big game effects on plants and communities. By using wire of different size mesh and variously-sized gates for exclosures inside of exclosures, differences in the effects of different size animals may be observed. Exclosures provide decision makers with some of the same problems associated with other techniques used to understand animal space. They are small, so sampling must be limited; sampling can destroy the utility of the technique. Because small, they can only represent a part of the area, a sampling stratum. Mueggler and Bartos (1977) dug through records and found data about aspen area exclosures that were extremely useful. Trends, sorted and damped by years of adjustment on a site, can provide the knowledge managers need ... before such managers are assigned after 5 or 6 years to another work area.
Mueggler and Bartos (1977) noted an ecological cross-current: "... wavyleaf thistle (Cirsium undulatum) apparently was favored by aspen removal at Big Flat, but by a closed canopy at Grindstone Flat." They explained the difference being related to a 600 m elevational difference between the two areas that resulted in differential cooling and available moisture.
Platts (1981) studied a stream protected for over 30 years by a fence around a forest guard station. Clearly the objective of putting in the fence was not to provide a baseline condition or exclosure for comparison of the effects of sheep grazing outside the fence, but it did. It may be that similar areas (e.g., wide vegetated areas between highways or inaccessible plateaus (natural or those created by mining)) may serve for comparisons.
Site Interpretation
There are special places that need to be seen and experienced. Documenting the universal feeling that seeing or being in some places stimulates people is like documenting the need for breakfast. Such places vary widely, so presenting a list of all types will not be done, but at least people can agree that there occur unusual experiences of beauty, e.g., the feeling that comes with seeing certain managed forest stands or a tight collection of wildlife management practices. Look at that! is all that is needed to get a response, but more is needed because "notice" is rarely sufficient. Increasing numbers of people are jaded by television viewing. (They have seen 10 close-up examples of nature, far better, far more intimate, than any manager can hope to provide.) Increasing numbers of forest visitors are urbanites and cannot see what the manager sees. Interpretation is needed.
The objectives of the interpretation system are:
The inputs for the system are the range of information about the site and the specific objectives (e.g., to demonstrate early human dependence on small mammals). The time available and the reading or listening speed of target groups are critical to the input process. Use of multi-media is needed both because of diversity among people and because of effectiveness of each medium to transmit information of a particular type.
The process can range from the educational queue for visitors to the sequence of messages, but the key elements are in answering: who, what, where, when, how, why, and so what?
The evaluation should include whether people saw what was intended and if behavior (e.g., the viewer's blood pressure or littering) changed. (The past record or a before-"treatment" and after-treatment of the viewer is needed.)
Adjusting to future trends in the area as well as to the people (including the percent of people who return) is essential.
Inventories are needed to document the conditions of faunal spaces. With faunal abundance estimates, it may be possible to relate these conditions to richness and abundance. Always a danger of collecting too much or too little, it is essential that the risk be taken. The needs are for:
Forest Inventory and Analysis, formerly "Resources Evaluation" is an endeavor required under the Forest and Rangeland Renewable Resources Act of 1974 and the McSweeney-McNary Forest Research Act of 1928. Workers periodically inventory the amount and conditions of the forest of the nation. It takes 3-4 years to complete a statewide inventory and they are conducted about every 10-20 years. These inventories can provide valuable information about the forest wildlife resource such as:
The distance of forests from water (in Michigan, USA, one third of the forests are within 1 mile (5-km of open water)) related to animal water needs, to human use of areas for fishing and other wildlife resources uses, to potential impact of harvesting on water quality and the fishery, and to distribution of land by site index, thus the basis for assessing forest dynamics.
There are many ways to obtain these data. Coordination of such efforts are difficult. There are hundreds of databases (e.g., Lander et al. 1979) but they are difficult to locate and most require extensive work to achieve compatibility with hardware, software, or objectives.
McClure et al. (1979) described multiresource inventories, an expansion of the traditional timber inventory (e.g., Spencer 1983). Sheffield (1981) showed how multiresource inventories made by the U.S. Forest Service and cooperators could be used to evaluate the conditions for 10 species of birds. Dissmeyer and Cost (1984) described watershed conditions based on the inventories. Craver (1982) used the inventory to describe the distribution and amount of honeysuckle (Lonicera japonica) (an excellent food and cover plant but often a problem in forest regeneration work).
The beauty of having baseline data, the stuff that does not change or that is historical (like the deer harvest last year), is that it can be used. It does not wear out. It can be creatively transformed (e.g., the logarithm of x+1; CAP9072) to gain new meaning. It can be correlated and analyzed wherever there is a new hypothesis that animal A is a function of X or any variable in the database.
Grosenbaugh (1973) described how a computerized geographic location system was being developed and how results of inventories could be mapped. Fales (1969) demonstrated computer mapping potentials for a wildlife area. There have been many advances since 1969 in hardware and software but, sadly, there are few faunal system managers who have matched inventory to place, place to a hundred known factors, and factors then to planned forest harvests and largely predictable changes in faunal populations. Animals are largely a function of their spaces. To know spaces and to computer-map them is to know populations.
Baseline data are needed. They must be preserved, turned over to successors, perpetuated, used, and feedback applied to add to them factors which are needed as environments and knowledge of them changes.
Area
Area is a human concept symbolized on maps. Animals actually occupy volumes but, laying aside that concept temporarily, even in two-dimensional space they occupy areas in which it is energetically efficient to move and gain food and other life needs. There are areas of uncertainty for animals; there are zones in which the ears only provide information. There are areas to be defended (called "territory") and those areas which, if entered, a fight, not likely to the death but very costly, will likely occur. There are seen areas, heard areas (functions of sound attenuated and hearing acuity), and smelled areas. Microtus townsendii, for example, has hip glands used in area marking behavior (MacIsaac 1977). Other animals have similar glands and mark areas. Whatever the purpose of such marking (mate attraction, area ownership or control, or simply information such as "I have been here before"), such marking creates areas of faunal importance invisible to the manager. It is likely that knowledge of these areas will help managers understand the meaning of area in density estimates (animal abundance per unit area), will help understand how highways and other land use changes cause unexplained disruptions of animal activities due to changes in these unseen areas, and how managers should try to include such areas, not disrupt or partition them.
All fauna occur in an area. Management always involves area. (CAP145 provides conversion for metrics and CAP132 calculates area of a polygon from entered points along the perimeter.) "Sanctuaries", "reserves", "preserves", "refuges", "wilderness", and "parks" are all words used by different people in different areas of the world to mean areas for wildlife. They emphasize, depending on local or legal expression, degrees of protection, usually from hunting. "Wildlife management areas" may include internal refuges or protected areas. There is no known right definition of each. CAP06 provides some, but local use will prevail. Herein, a managed area could be all or part of a National Park, a National Forest, a National Wildlife Refuge, similar state-owned area, or a part of a corporate or private holding. Wildlife agencies often call areas "wildlife management areas" and manage them, or parts, as they see fit.
Management units are parts of these areas. They are often hunting units, areas with different regulations such as those limiting the animals that may be taken or the length of the hunting season. Elsewhere they are administrative and only designate areas within which staff work or have responsibility. Administrators change the name of forest area units but the progression is usually: region, forest, working circle or unit, compartment, stand, and operation (e.g., what part of a large stand will be treated in some special way).
These areas are identified in many ways. Some are administrative: e.g.,"you take half." Others are based on ownership lines, others on topographic features (e.g., mountain crests), others on roads: "everything west of Rt. 1." Some are based on watersheds. Increasingly none of these make as much managerial sense as they once did. Each was limited (which is why there are so many ways to designate areas). Now it is feasible, and I think desirable, to imagine all faunal areas as small square map cells, thus squares in the forest. See Fig. 7.2.
 |
| Fig. 7.2. A grid can be placed over any mapped area and information recorded about what is in each cell. Individual-factor maps are created such as one for the elevation at the center of a cell, the presence of a stream, or an ownership code. |
Any map with any features can be overlaid with a square grid of lines. Every square can be located by an x, y coordinate. By using computers, maps can be drawn of any feature. There is no need to decide on a fixed means for designating a wildlife area. This year the area may be the watershed, next year, only the south-facing slope of the watershed. Suboptimal designation of wildlife areas suboptimizes faunal management. A flexible process allows feedback to correct the designation.
I have learned that in developing countries where the U.S. refuge or park model is attempted, often a line is drawn on a map and an area designated. Not only is the U.S. concept for parks probably suboptimal in developing countries, but also where the boundary was drawn was also suboptimal. It is possible to state a set of criteria such as "minimum impact on villagers", "maximum species richness", "maximum access for tourists", "minimum cost of forage production ", etc. and to allow computer mapping to indicate how well each cell satisfies these criteria. Then they can be weighted, a new map produced, and then the management area (or areas) boundary can be drawn.
There is much literature on what is the optimum size for wildlife and related biological preservation and management areas. The answer begins with the question: What are you attempting to optimize? State your objective, then the constraints, then we are in business. Until these are produced, the debate will continue. Often simulation helps when objectives are difficult to state. " What if these boundaries were used, then what would the map look like?"; "what if these ...?" In some cases, intuitively, the answer for the optimum size is "as large as possible." It is extremely important that all benefits as well as all costs be considered. Faunal system managers often point to people constructing dams, highways, and similar developments through wildlife areas as not counting full costs or the "externalities" or the benefits foregone over the long run. In creating new wildlife areas, wildlife managers need to be subjected to the same rule and need not fall under their own harsh judgement. The optimum area decision will include the foregone benefits from alternative uses in its determination. There will be portions of areas lost; sometimes whole areas. That is the nature of the game (Chapter 17).
Seasonal Range
In the western U.S. and Canada (and elsewhere in the world) snow depth builds rapidly in the high mountains. Animals there hibernate or move to lower elevations. These lower areas are called "winter range." Winter range is a much more complex idea than area to which animals move. It includes variable dates of first snow, snow depth, what capabilities animals have to move and feed through snow, when animals start to move into (or out of) the lowlands, the ancestral migration routes, use to which the lowlands have been put by humans (e.g., farms, reservoirs, roads, towns), the abundance and quality of the food, and direct mortality (e.g., poaching, predation). In other areas there is an alternative area usage, a reversal of the snow and energy-loss phenomenon of the cold regions. In the arid zones, the riparian forests are intensively used by animals, strongly analogous to winter range.
When the snows melt and forage becomes available, animals return to summer range. The concept is intuitively simple but it has profound consequences. In some areas, only 10 to 30 percent of an entire management area can be classified as winter range. The amount varies each year with snow depth. The relations in the system are not linear. An additional foot of snowfall laid throughout a convoluted valley system over a large area can withdraw thousands of acres of land from foraging animals.
When I moved to Idaho from the Eastern U.S., I found the concept of winter range difficult to grasp in its entirety; I had to live with it. It included: a winter with light snows allowed a large winter range; many female deer and elk survived; many returned to the summer range. Production of young was high. If in the next year the snowfall was heavy, large numbers moved to the valleys; forage was sparse; large numbers died; the range plants were hit hard resulting in their reduced vigor for 3 to 10 years; recovery of the population could be slow, even with good reproduction on the summer ranges. The valleys are now filled with people, roads, buildings, reservoirs - all having destroyed foraging areas or blocked animal movement to foraging areas at lower elevations. Comprehending winter range (and similar phenomena related to seasonal shifts, long range as well as the above short-range migration) is difficult. It is a massive geographic phenomenon, dwarfing the ego of the boldest manager seeking to control sensitively any population.
The controls are limited, but managers can resist developments that block migration routes, stay attuned to annual snow depths and range conditions, maintain flexible harvests to reduce range pressures, and restore the areas heavily "beat down" by winter-stressed groups.
It is evident that animal movement is related to snow and temperature. I believe animals as "energy balancers" engage in similar subtle movement in response to other factors. (See Moen 1973.) They shift time spent between elevations and aspects, between wind-swept ridges where there are few valleys, between conifer clumps and open stands. In the northern states, deer move to "yards" where winter conditions are favorable.
Relevant Areas
Portions of some natural resource or management areas are for the animals and very specific users such as those who do baseline research studies and monitoring. Other parts of these areas are for intensive user such as anglers, hunters, and animal observers. Except for hikers who will go almost anywhere that there is a trail, and mountain climbers, these users frequent very limited areas. Rather than comparing total areas or allocating funds based on total area, it is appropriate to estimate the area that 9 out of 10 people will probably (0.90) use and also the probable days of use over a 10 year period. Using these criteria usually reduces the area for management significantly. The cut can focus attention, clarify work responsibilities, and improve budget allocations. The "area sword" has two cutting edges. For example, U.S. Forest Service land contains 90 million of the 500 million acres of U.S. forest land capable of growing more than 20 cubic feet of wood annually. The statistic can be used to boast of control or to absolve responsibility; the need suggested is for understanding the managerially relevant area.
The relevant area is usually a zone around access points (e.g., boat landings) and roads. The potentially useable area needs to be estimated based on reports of hunters and other users, observed kills, radio tracking of hunters and recreationists, viewscape maps, trail sensors, and other methods. Simple time-rate-distance relations can provide a first estimate of the width of the potentially useable area. This may be the area where most faunal system management should be conducted.
The Unique Square-Meter
Computer technology has allowed managers to think in new ways about wildlife area. Once it was essential to aggregate land into large conceptual units like regions or watersheds. Now it is possible to think about very small units, mentally working in the reverse order. Satellite images are made from pixels or picture elements. These cellular images of Earth's radiations are only one factor among hundreds that are mappable. Commercial computer programs are now available for manipulating such maps. The size of each map or land cell is an important consideration. There is no optimum. Size depends on objectives, available budgets and maps, and required accuracy.
Animal-to-space relations are needed but not as much as some people think for reasons already discussed abundantly in this book. It would be very desirable to know the relationship of animals to many major variables, such as in:
Nt+1 = f (at, bt ... nt)
Predictability is only possible in the sense of potential populations or standard conditions. Animals are influenced by people, even on wilderness areas! Animals are hunted, subsidized, protected! Every site is unique! There is equifinality (Angermeier and Schlosser 1989:1460), many pathways to the same population tomorrow! Non-managers, laboratory-bound scientists, readily conceive of one precise relationship. The alternatives needed in the field are pathway models, expert systems, and models that account predictable change and variety over time. Emphasis needs to be on unique entities of a population, not on mean conditions for which there exists only one unique entity. A technique that evaluated a site today yields wrong results tomorrow. The needs are rarely for estimating of the number present in a habitat, but for the potential for that habitat. Once that is decided as the objective, then the analyses shift to relative differences between faunal areas. Is this area better than that? Based on the conditions present and observable by analysts, conditions positive and negative, conditions stable or with a high probability of change from a one balance to the other, these can be determined at a very high level of confidence by a student of a species or life group. That the well-estimated population of X in many areas does not regress well on some index of current habitat goodness or suitability is of no surprise. Maximums (potentials) should provide a good regression. Pure chance may match up a population with a treatment. A brief, expensive test to determine this would be audacious given the number of species that must be mastered in order to bring the faunal system under semblance of control.
In geographic information system work, the cell-size question is one of precision. How precise will you make your measurements? Will a cell be 1 square kilometer or 0.1 hectare? It depends. Most people want very small cells because they realize how variable land is. They are familiar with their house and yards. They know that the fountain is small, just as is a corner of flowers, a walkway, and a spot that for unknown reasons will grow nothing. All of this is in a small area 10m by 10m. How then can realistic work be done with larger cells? Even with computers and their inconceivable speed, cell size has to be limited for most problems to be solved. In Virginia there were about 1.1 million cells representing the entire state in a computer data base. Each cell was 1/9 square kilometers (about 27 acres). There were factors known for each cell such as average slope (CAP113). All outdoors people know that slope changes quickly and is varied (except on wetlands). Standing on a large rock or stepping into a stream channel can produce grave doubts about the meaning of average slope. Yet slope estimates for cells can be used, have been, and can be very expressive about average conditions ... and these estimates are more accurate than a map with no slope information, one requiring mental interpretation of the denseness of contour lines, or one with large areas painted one color indicating slope changes of 10 percent. The tension that the systems person feels is that between working with nearly complete ignorance one day and great knowledge the next, between being praised for precision used in small areas and criticized for unusual skepticism about large-area observations. The computer mapping environment is dynamic and its beauty is in the advances made, almost self-generated, by the technology - the hardware-software-staff system.
Every square meter of a forest is unique ... absolutely. There will be similarities, but like egocentric people who know they are unique, each plot has combinations unlike any other. Pielou (1969) observed "not only does each species differ from every other, but also all the individuals within anyone species are unique. ...It can truly be said that no two of the individual units making up a community are alike and that each of them, throughout their lifetime, varies continuously in a manner peculiar to itself. ...The components of a community are never the same at two successive occasions." Facing the uniqueness of areas realistically, the forest faunal system person needs a geographic information system with 1 square meter cells. (Smaller, perhaps, but enough is enough!) For each cell in large faunal management areas I could potentially have 50 factors or more, and then I would have conceptual control, be able to understand what goes on in every place on my area, explain differences, predict likely future faunal systems, estimate impacts, etc. This is now conceivable and almost executable but even with computers, the data storage becomes enormous (how many meter-sized cells are there in a moderate 7000-hectare wildlife management area?), the hardware is beyond personal computer limits, the allocated costs of computation, time allowed for certain types of emergency decision making (e.g., forest fire fighting and lost-person rescue work). One meter may be too small for work in forest faunal resource management which always involves animals with fairly expansive and variable home ranges, populations of animals (not individuals), and with a seasonal as well as a spatial dynamic (e.g., in rotating forest harvests over an area). It will soon be the proper size.
I cannot provide an answer to the optimum map cell size. In urban yards-for-wildlife, I would work with a 1-meter cell and define "the yard" as the owner's and all contiguous yards. This would be the managed unit. I have seen powerline corridor analyses done with 1 square kilometer cells. This, it seems to me, is too gross for any purpose, but in very large areas that are not variable, where data are scarce, and where objectives are to avoid bad "spots" or cells, then such maps may be of service. I believe the 1/9th square kilometer represents a reasonable compromise for many uses in natural resource planning. It is too gross for centerline location of roads or trails, but too precise for printing planning maps, boundaries, and riparian vegetation areas. I suggest that most applications of geographic information systems can be handled as a 3-level operation. A gross system can be created, for large areas (e.g., regions of 20-25,000 sq. km.), perhaps with one-square-kilometer cells. Then at an intermediate level, cells can be developed (perhaps 1/3 km on a side) for areas of special concern and intense planning. The third level would be at the 10 meter x 10 meter cell size (called Alpha Units by Giles, ms)(with images of cover now available from satellites) . This size allows fair discrimination, requires abundant data collection, entry, and verification, but is feasible for many areas with proper scaling of work, equipment, space, and staff. Past efforts to do extremely detailed, large-area work have often failed. Improved technology and programs are reported regularly so the problems are diminishing. The warning needs to be sounded. Start at level 3, with very precise cells and data but with a very small area that can be expanded easily into larger cells of the same metric. Otherwise, start with large cells for a large area, then, using it, locate parts of the system that need greater precision and more data collected and processed.
Giles (1988) presented warnings about creating large geographic data bases without appropriate plans for their maintenance and use. One beauty of data base systems is that with each use, the per unit cost goes down. The data are not used up! Once such data are available, then the creative juices of managers invariably flow. The systems can be used for many faunal system purposes, then uses become readily apparent in planning, for optimum site location, for corridor location (e.g., roads, utility right-of-way (Giles et al. 1976), trails), for points (e.g., airports (Koeln 1980) and solid waste processing sites). Once the wildlife agency has such a system, then "knowledge is power" and it can use it in an active, progressive, cooperative mode to improve all resource management in an area and thus wildlife within that context. Otherwise, it can be used defensively, assuming land use of most types is likely to be harmful to some fauna and therefore to be stopped, delayed, or diverted. I favor the former.
There is a debate over what methods to use to enter map data into a computer and how to use it. The major options are the square or hexagonal cell and the polygon (including the variable-size triangle). The debate is extensive and cannot be reviewed here.
The manager needs to be able to use the data and (1) to select from the entire area a relatively narrow line or corridor that meets at least 40 criteria of goodness and that has ability to allow the factors that meet those criteria to change over time (e.g., trees to grow, soil to erode); (2) to select a point that meets similar criteria (e.g., for a water hole, a tourist center, a hunter camp); (3) to select an area that meets such criteria (e.g., pest outbreaks, viewed areas, fire hazard areas, taxation impacts); (4) to select a volume that meets criteria (e.g., a forest layer, a ground water volume); and (5) to transfer effects between cells and layers (e.g., runoff, groundwater recharge, wind in forest layers). The emphasis I wish to make is that maps need to be drawn by computer but they also need to be decision aids; they must participate, by design, in optimization. To my knowledge, only cellular systems (or polygon systems converted to cellular systems) can perform consistently in this manner. Overlays of polygons can be made and used in making decisions, of course. Cell-based systems, however, allow impacts or costs per unit area to be accounted, each incremental change to be readily accounted. Fig. 7.4 shows a computer-produced map of a power line corridor selected from thousands of possible routes between two specified points.
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| Fig.7.4 A computer-produced map resulting from analyzing alternative routes for a powerline. The analysis included 12 weighted dimensions of impact, 40 variables including wildlife, costs of construction and maintenance, and successional changes over 30 years. Each map cell is 27-acres. Two lines are shown for a vast area - one proposed by a power company and one computer-selected. Shades of gray in each map cell indicate likely long-term total costs. (Map developed by A.B. Jones III.) |
The company-proposed corridor can be compared to such selected routes. One use is in court hearings in which a company-proposed route(s) is compared to routes suggested by opponents or a public body. As in other types of developments and land use change, there is no "best place" (the typical question). All development modifies faunal space and thus is good for some animals or resources in that space, bad for others. The impact question needs to be formulated, usually, as "where is the least bad place to put X?" or "where will net positive effects of X be maximized?" Once done, the solution method can usually be found among those labeled cost, risk, or loss minimization. The literature of economics and operations research (e.g., Taha 1971) are full of such methods. Overlay maps (without computers) are useful. After manually placing 6 or 8 overlays, no further discrimination is possible. Wildlife decisions usually involve more than 8 factors but using 8 usually produces an improvement in decisions.
The dominant vegetation can usually be mapped with the aid of low-altitude aerial photos or satellite images. Fies (1983) used satellite images to identify hardwood and coniferous forests (about the only level of discrimination consistently possible from these images), then added data on slope, aspect, and elevation and was able then to specify potential forest type in each cell. Imagine the power this gives to the faunal manager able to relate fauna to forest type and age!
A Question of Managerial Control
The manager seeks control over the benefit-production-and-cost system of the forest. The faunal spaces are one part of the production system. Much control is possible, but there are limits. Can precipitation be controlled? Politicians? Poachers? The answer is yes, but it requires a particular perspective about control. When knowledge is gained about something, that thing begins to be brought under control. Models are knowledge units. With them, risks are reduced, predictability is gained. Spies help bring an enemy under control. Models help bring climatic factors under control. To name something begins to bring it under control, for then it can be studied, information shared, the entropy of undirected study reduced. There are many things that cannot be brought under full control. A 100-percent efficient machine is known from elementary physics not to exist. Yet the concept remains. Control, like efficiency, is sought even though it may never be obtained.
To know that one forested slope receives more isolation than another slope throughout the growing season puts the manager in control. The evapotranspiration and energy input differences can be noted. These help explain differences in forage on a site, in animal population behavior relative to it. No longer responding to the land as if it were a whimsical earth-god, the manager gains partial control, at least some potential power, for now he or she may decide to do more (or less) on this (or that) area, now, because of knowledge.
In a manager-as-driver-of-a-car analogy, the driver is clearly in control but as every driver knows, control is relative. There are wind gusts, irregular pavements, breakdowns, forgetfulness (as in filling the gas tank), and other aspects of a purposefully controlled, high-tech activity, that deny "control" as a 100 percent, finite condition.
The manager seeks control; the dynamics of this two-word phrase is very important. The manager who is statistically versed knows that experimental designs are largely made to control statistical variance. To know several factors and to have data about them allows the researcher- manager to control or reduce the measure of variability in the relations of a factor (e.g., animal density) to environmental factors (e.g., forage). Measuring and relating forage and density may give a gross predictive or explanatory relationship in a model or equation, but knowing insolation, soil texture (bulk density), and slope may give very great predictive power (e.g., may move the R2 index to the goodness of the model from 0.3 to 0.8). This is gaining control - conceptual power - over the system. The manager may not be able to change or manipulate land slope, but he or she may select study sites or work areas differently because of such knowledge. He or she may not be able to change soil bulk density, but will know the effects of hunter-vehicles or logging equipment compacting soil and thus be able to explain changes in forage and animals responding to it. Change insolation!? Perhaps not, but changes in cloud cover or particulate air pollution might be projected or hypothesized and thus their effects on wildlife and other phenomena known at a high level of confidence. To know these consequences or even to be able to begin to estimate them with preliminary tools (not just good guesses) brings the forest faunal manager into control of the system.
In rough terrain in the early morning, the hunter or woods worker has surely experienced the sun "coming up over the ridge." It may be very late in the morning before plants on a site experience direct isolation. To know this primary, driving, ecosystem force on every forest site (perhaps map cell) seems to me almost essential for managerial control. No (or little) field sampling is needed. The path of the earth is fairly well known as is the trigonometry of light angles. The wildlifer may not be in control of the sun but ability to estimate the rate of tree height growth on a mountain ridge provides him or her power to estimate changing solar radiation on an adjacent slope and thus provides insights into patterns and differences in animal density, behavior, forage quality and quantity ... the stuff of the faunal manager's decision system. Knowledge of faunal spaces, particularly the abiotic factors of such spaces, gives decision power and control.
The previous section was about "area." Area perhaps has more influence on faunal populations than any other factors. The population is a function of density and is clearly and simply number of animals per unit area. The magnitude of hectares typically overwhelms any other descriptive conditions about the hectares themselves. The manager needs to be concerned about energy, edges, and many other factors. Area is the place to begin for faunal resource system control.
Global positioning satellite (GPS) technology can help locate corners and improve area estimates. Wild area surveys across the U.S. are surprisingly inaccurate, resulting in faulty estimates of area. The problems of estimating population density begin with the estimates of area, not the animals.
Classification
There seems to be a need for a common system for classifying, inventorying, and analyzing natural systems in which faunal resources exist and progress has been made (Marmelstein 1978). They are needed for national and regional inventories and their analyses. Selecting the most useful for a stated period is a desirable task, and, with feedback, can be improved. There is no need to avoid committing to a common classification if (a) it is reasonable and the best seen (by a majority); (b) it will be held for a few years (avoiding costly re-mapping, data transformations, and re - analyses); and (c) if it is known to be under study and that change is possible at a designated time. There is good reason, however, to consider an alternative.
To classify land means to name homogenous groups. This furthers the illusion that a thing named is a thing explained (cf Beadle 1974:307). The name is thus a code, that, if well-selected, will communicate many things about an area to others who understand the code. Anyone who has been to the Pacific Northwest understands "mature Douglas fir." It is not simply a statement about the dominant tree but about soils, moisture, understory vegetation, and wildlife. Such a "class" provides information for many users. Does it provide information for most users? For a few users with costly and risk-filled decisions? How many classes of land must be processed for a person to be able to map the range of a salamander that frequents old Douglas fir stands but also several others? Dominant vegetation is one basis for forming classes. It is good; it is predominant. It was developed bc, before computers, and is influenced by conventional map making.
Perhaps what humans readily see is not "seen" by animals; perhaps faunal responses are to infrared or other electromagnetic stimuli, and to olefaction. Continuing to assume that animals react as humans may prevent achieving the promise of "habitat classification", said by Steele et al. (1983:83) to be:
Lotspeich and Platts (1982) observed that resource inventories without classification are unorganized lists and that planning efforts require inventories. Their approach attempted to unify land and aquatic system categories; emphasized natural attributes (not present or projected land uses); and progressed from the first-order watershed as the smallest unit, the "basic ecosystem." The system suggested was hierarchical, namely: 1. Domain, 2. Province, 3. Section, 4. Region, 5. Land-Type Association, 6. Land Type, 7. Land Type Phase, and 8. Land Site. Streams are classed at level 6 because they are continua with a variety of land types. Bailey (1978) had a very similar taxonomy (Table 7.2). The system is a reasonable basis for inventory and for deductive work in unknown areas. As in other systems, difficulties exist due to scale, and in separating (if desired) fire, grazing, trapping, hunting and logging and dam affects from the "natural" attributes of an area.
| Table 2. Bailey's ecoregion element hierarchy based on that presented in Fink and Elder (1982) as adapted from Crowley (1967) and Wertz and Arnold (1972). | ||
|---|---|---|
| Level | Element Name | General Characteristics and Comments |
| 1 | Domain | Subcontinental area of similar climates |
| 2 | Division | Single regional climate at the level of Koppen's types (Trewartha 1943) |
| 3 | Province | Broad vegetation region with the same types of zonal soils |
| 4 | Section | Climatic climax at the level of Kuchler's (1967) potential vegetation types |
| 5 | District | Part of a section having uniform geomorphology at the level of Hammond's (164) land surface form regions |
| 6 | Land Type Association | Group of neighboring land types with recurring patterns of landform, lithology, soils, and vegetation associations |
| 7 | Land Type | Group of neighboring phases with similar soil series or families with similar plant communities at the level of Daubenmire (1968) habitat types |
| 8 | Land Type Phase | Group of neighboring sites belonging to the same soil series with closely related habitat types |
| 9 | Site | Single soil type or phase and single habitat type or phase |
Pennak (1978:65) said about the running stream faunal volume: "It is obvious that we are dealing with an enormous variety of running waters where there are wide ranges of chemistry, physical qualities, and biological details, and where single-criteria and several-criteria systems are of limited coast-to-coast value." He suggested 13 criteria. [If there are only 2 states of each, the options are merely 8,192 types of streams!] Those were: width, temporary or permanent flow, current speed, substrate, winter and summer temperatures, turbidity, total dissolved inorganic matter, total dissolved organic matter, water hardness, dissolved oxygen, rooted aquatic vegetation, and streamside vegetation.
Classification is an effort to aggregate knowledge, to lump things in ways that have meaning or utility. The ways must be few and mappable. Over-aggregation is almost assured, no matter what the practical problem. (General interest, breadth of curiosity, artistic endeavor, or public education are not the topics.) The result is likely to be suboptimal decisions and thus resource use.
If the greatest possible refinement of data is used, when new problems and new needs for locating areas with a special set of characteristics arise, a unique class can be defined for those new situations. A new map can be created, perhaps one never seen before ... and perhaps useless tomorrow. This is called dynamic classification (Williamson 1981). After the map is discarded, the system that produced it remains. The map becomes more like a newspaper than a thing to be preserved in a library. One day it need be only an image produced or controlled by a computer.
On a conventional map, more than 20 colors are rarely displayed. Few people can easily discriminate among 3 shades of green or other colors. In most faunal space work, it is easy to conceive of areas being needed to be analyzed by: (1) high-low, (2) north-south facing; (3) near-distant from water; (4) vegetation groups 1, 2, 3, or 4; (5) near-distant from roads. There are 64 categories suitable for mapping and needing color codes in this simple list of 5 items. Faunal space information cannot be mapped. The above seem at odds with expressed needs for maps serving the layperson, being simple, focusing on priority habitats, and being standardized (cf Kusler 1978). They may be, but not necessarily. There are needs to be met that do not require the kind of creative involvement suggested above. Where are the "critical areas?" Make a map of the areas. The criteria for critical areas varies by states. A map could be prepared using alternative criteria. "Make an endangered species map" may be a reasonable demand. What is to be mapped - counties in which they occur, or potential habitats, or cells, or last known record, etc.? It is difficult to get people who make what appear to be reasonable requests to be specific enough so that a systems output, once delivered, could be judged useful.
Steele et al. (1983) briefly reviewed the debate over whether forest types of similar classes exist, whether all plant and animal assemblages vary and occur along a continuum, or whether there is some intermediate condition (Collier et al. 1973). They were fairly pointed in suggesting "get on with it."
Although this debate may still be of some academic interest, it need not preoccupy natural resource managers and field biologists who need a logical, ecologically based environmental classification with which to work. We acknowledge that continua may exist in the landscape; nevertheless, our objective is to develop a logical site classification based on the natural patterns of potential climax vegetation. Local conditions that deviate from this classification can still be described in terms of how they differ from the typal descriptions presented here.
Cole (1978) reviewed lake classification and observed that seeking to describe lake typology as an objective has not been without value. Out of the effort has emerged patterns that have advanced limnology and ecology. He said "continuing the search for pigeonholes into which lakes can be fitted naturally on regional bases can lead to understanding of local aquatic habitats and their potentials. There is, however, little chance that a couple of adjectives can explain the complexities and dynamics of a lentic habitat."
Hoffman and Alexander (1980) used "plant association" to mean forest stands that have the same overstory and understory, and "plant series" to mean those having only the same overstory. Within-series classes were based on differences in understory. They proceeded to analyze a forest on the basis of potential vegetation, not that which resulted from extensive past disturbance.
The capabilities now exist within geographic information systems for any manager to ask for a unique map to meet a specific need. For example: Show me all sites above 900 meters with conifers adjacent to water on north-facing slopes with steepness less than 15 percent. A manager might be able to use conventional maps and create such a map but at great costs of time and effort, and the results would be of questionable accuracy. Often, time for making a response is the resource in shortest supply. The map is needed tomorrow in a critical meeting! It is to be used for a specific purpose for one life-form in one managerial context. It must communicate well, given the people likely to be at the meeting.
Just as a person uses a plant key, working through taxonomic criteria until a specimen is classified, so can a manager specify criteria, then in reverse order find the "specimen map cells" that meet those criteria. The criteria may be dynamic (as they are in so many managerial situations); the data may be revised or new data added and a new map produced. The new map is a tactic for resisting suboptimization (Williamson 1981). Logistic regression has been used by McCombs (1998) to find the probable sites where the northern flying squirrel will be found.
Because of the capability of computer-based dynamic classification, the extreme variability in types already named, the occurrence of identical dominant vegetation with extremely different conditions (expressed equifinality), extreme overlaps in type occupancy by fauna, faunal differences greater in forest age classes than in forest types, limited utility among resource managers (though within-a-resource, use may be high), a visual limit to the number of types used that is imposed by cartography (about 20), and the broad transition bands that occur between some types, I suggest that faunal system managers be classification aversive. Shelford (1963:238) included the grizzly bear in a classification system and used the "spruce-moose" type. Even this will not overcome the above difficulties. Typing areas may be necessary but, for the long run, since change now seems to be exponential, eclectic emphasis on faunally--influential factors now seem appropriate.
Primeness
Giles and Koeln (1983) argued for using a concept of agricultural land "primeness" and demonstrated how it could be calculated and used. Rather than using a simple concept of "prime farm land" (two options, prime or not-prime) they suggested that primeness, a continuous variable, could be meaningful. Somewhat like "suitability", "prime" denotes a maximum and implies that"less-than" can be discussed, even to zero primeness. "Suitable" however connotes a yes-or-no condition, does not suggest a maximum or minimum condition as a basis for comparison, and does not contain a time concept, one related to forest succession in an area or to the suitability "next year." Habitat "suitability" models and indexes (U.S. Fish and Wildlife Service 1980, Collotzi 1980) are now abundantly used so "suitability" will probably remain in use. Lorio et al. (1982) described a stand risk rating for southern pine beetles. Although the concept of risk is associated with beetle damage, the rating is an insect habitat primeness concept. The insect occurrence (frequency of infestation among stands) cannot be well predicted, a situation not unlike that for other animals. The utility of primeness models and their results is that land (each cell) can be evaluated for the probability of how well it meets the present as well as future needs of a species or life group. Especially important in land-use-decision-making and impact analyses, areas of lower primeness may be selected first for use, saving those areas of greatest primeness for later. This results in preservation of future options. Similarly, tradeoffs can be made among cells, estimating the long term species- or group-specific benefits from cellular areas and their combinations. It may be that 2 areas with primeness 0.45 will substitute for 1 with value 0.9 ... but then cumulative scores over many years need to be studied.
Quality Primeness, suitability, or other terms express area quality. Quality is a species- or life-group specific concept, varies seasonally, and over time. It is essential that managers view area size (quantity), as if through a stereoscope, with area quality. One-thousand hectares for an animal life group is, if of a quality index of 0.4, equivalent to 400 hectares of index quality 1.0. Agencies may think they impress the public with statistics about areas held or treated annually. Some people want to know which areas; of what quality; and what was the change produced? Land acquisition and set-aside programs need to be based on area and quality. Rayburn and Giles (1975) compared areas for acquisition for deer management purposes based on the net energy that these areas would likely supply over a long period. Rough topography, temperatures, and snow may function to cause energy drains to deer. Available forage produced and its metabolizable energy content may contribute to the population. Areas of the same size have very different potentials for supporting wildlife or providing benefits for users.
Because quality is so important, also important along with area (for what is the significance of zero quality?), then questions of minimum areas become almost unanswerable. I suspect an expert system (CAP54) will be developed to help determine minimum sizes for faunal management areas. The species-area curve (see Chapter 4; CAP2041) has been discussed. Where species richness is an objective, the curve may provide insights into the minimum area size, but it will not free the manager or the public, represented by managers, from making the decision about the proportion of the area under the curve that will be acceptable.
Total area is important to some species. In general, areas that are at least 50 home ranges in size are needed. This assures genetic diversity sufficient to reduce inbreeding and to assure a viable population. In some areas with large animals this cannot be achieved and this presents the problem experienced with other animals, namely, what is the smallest patch size? A patch is a small community like a clump of trees in a grassland. There is evidence that each patch has to be larger than a particular size for each species or it will not contain that species. If an animal requires 5-hectare patches and there are 50 patches saved for it, each 4 hectares in size, then the species will probably not exist in the area. It may be asserted that 200 hectares have been preserved for it! The intention was good; the execution flawed. Each species needs to be studied by observing areas of many sizes and plotting the size of patches and species abundance, at least presence-absence, and proximity of other patches. "Corridors" or connecting vegetation units are over-emphasized.
Lynch and Whitcomb (1978) concluded from their studies that breeding birds in the eastern U.S. deciduous forests have declined in richness and abundance due to decreases in forest patch size. Birds in large forests are not so affected. Birds most affected are forest-interior species that migrate out of the areas in winter. They thought that small forest parks are ineffective as reserves for avifauna because they are too small, too far away from generator populations, and have too much human disturbance. They were concerned about the likely extinction of many forest bird species and called for a halt in the trend toward insularization of the remaining forests of the Atlantic Coastal plain. Harris (1984) called for the same in the Pacific Northwest.
We can return to the questions of how much area should be used for forest fauna and what is the optimum size to be designated for such management. Those are complex questions and there is much debate over what are the proper policies to provide answers. The questions are leading. Refuges and reserves, dedicated areas, are one way to manage wild animals. Setting aside areas is not necessarily best and rarely necessary in light of the context and other options available to achieve objectives. Dedication of land is a conspicuous act easily done by politicos. The hard work begins afterwards and not by those signing the grand documents. Perhaps dedication and public notice are necessary precursors, but the effects on wildlife that seem to come from "establishing a park" are really from altered habitat destruction, stopping poaching or other critical activity, and actively managing spaces. The idea of a refuge as a center from which most animals disperse seems largely unsupported. In protected areas, animals behave differently to humans than do animals outside. The richness and densities desired (stated in objectives) can often be achieved without reserves. In some countries the area of complete protection causes social as well as ecological problems resulting in negative benefits at high costs - hardly the stuff of modern wildlife management. Without predators, for example, ungulates on protected areas often increase to numbers that destroy native plant communities. Controlling hunting or other animal removals as well as other behavioral controls are needed to protect wild flowers, butterfly and songbird habitat, forest regeneration, soil on critical sites, and water quality.
The needs for areas can be related to the local expression of a system performance measure, Q* - benefits from all species at low costs over at least 50 years. To meet demands for each species, area can be calculated. Then they need to be listed from largest to smallest. This may suggest the need for a large area to meet the needs of the most wide-ranging and lowest-density animal. This may not be sufficient, for there may be habitat needs for other species that do not overlap the range of the wide-ranging creature. Iteratively, the questions need to be phrased, high to low, "sufficient size for desired benefits from species 1? 1 and 2? 1, 2, and 3? ... etc." In some environments, meeting the area size requirements for species 1 may be sufficient. Meeting that need meets needs for all other species. Costs and available areas come into play. The manager may work up from the bottom of the ranked cumulative list, deciding on the greatest area that can be afforded that meets the needs of the most importance-weighted species in demand.
Generally, the smaller the perimeter-to-area ratio of a managed area, the easier the area is to manage. Irregular or long areas, however, usually enclose more species ranges. See CAP2011, CAP9062, and CAP9065. The more proximal are similar small areas of the same habitat, the better. There needs to be maximum opportunities for animals to find enough suitable conditions - whether these be nesting sites, food, water, escape areas, or escape from inbreeding. The criteria for parks or refuges are not of areas but of animals, all of these specifically quantified in the objective.
I find appealing the idea of identifying the species in an area of interest (or the species of interest) having the maximum home range (h) (Chapter 8). Then assuming an area is needed for at least 5 to 10 (g) of these groups, and there is some overlap (z) an averaged proportion of the home range size, then the area needed is:
A = hg - hz (g - 1.0)
CAP2000 allows the manager to play with a variety of assumptions or hypotheses about each of these variables. In some cases, detailed studies on one or more may have been done or are in progress. Often a species being protected for the first time is almost unknown. Deduction based on similar species and spaces is all that is possible. Like engineers, faunal system managers need to make estimates as accurately and precisely as possible ... then add a bit for safety. How to determine the "bit" is another question, but it can be added to the force-field in which the manager lives - accuracy, precision, confidence. The manager adds a "bit," a measured practical attempt at reducing the probability that an undesirable limit will be passed.
Wildlife is produced on many areas. All good animals are not assigned only to refuges or special faunal areas. Fauna are to be counted as satisfying objectives wherever they are found. There may be horror stories about habitat losses but few people will express how many extra animals or benefit units can be produced by more intensive management on the areas remaining. In some cases (most I wager), animal abundance losses can be more than overcome by intensive management elsewhere. Wildlife potentials need to be estimated. Loss of 100 hectares producing at 0.10 of its natural potential or producing animals for which there is no current or projected demand, may be overcome by managing 10 hectares producing nearly at their potential. Mitigation is a concept implying replacement in like kind lands lost to various projects such as dams. Acquisition of wildlife lands for the public to replace wildlife lands lost is often a desirable action but rarely can lands of equal value or function be acquired and long term maintenance and management costs be the same or less. If faunal system management "works", it may be better to require trust funds for management of residual areas replacing the animals lost, for the long run, not the area lost. The reality of lands needed is blurred by whether land for fauna should be studied as if it is producing naturally or producing as it might under sophisticated management. The latter brings into discussions the questions of cost. There is at least one book to be written on this complex topic and I cannot resolve it briefly here. I emphasize: (1) the manager can only count the additional animals produced as a result of investments; (2) benefits, not animals, are to be produced, seeking to maximize Q*; (3) without a view of a need for or the possibility of increasing B in Q* = B/C, there is no loss in the wildlife resource when habitat is destroyed or lost; (4) areas lost or gained (as when parks or reserves are dedicated) are meaningful only in the context of Q* where benefits can be enhanced from different sizes and arrangements of areas depending upon or viewed as a function of cost. Complete enumeration of the options, while not yielding a global optimum, will probably show preferred solutions and even several nearly equal "best solutions" over which the public, politicos, and pundits can squabble for years. The manager may choose sides in such situations, then laugh in defeat, knowing that the lost cause was equally as good as the one overtly supported.
Confidence
Readers may review the concept of "confidence" in any statistics book. See Fig. 7.3. Here I wish the reader to see that the level of confidence at which the manager works is a managerial problem, not a dictate of a journal, a professor, or a concept "acceptable throughout all of agriculture." When a manager uses statistical tests to determine if a fertilizer was better than another one, if these users were more satisfied than those, or if production averaged J kilograms per hectare, then a confidence level is needed. The manager will want to say "this is the case, based on my limited studies, and I'll stand by it at least 9 times out of 10." This simply acknowledges that he or she has not studied all possible situations, that they may have gotten a peculiar sample, and that they cannot be certain. Being wrong one time in 10 may give people the shivers when dealing with a threatened species or an advanced-age timber stand, but for most wildlife managerial decisions, the manager of the long term resource will not suffer much if decisions are made at the 0.80 level - the chance of being wrong only 1 time in 5! CAP222 and CAP121 allow the reader to look at the consequences of changing the confidence level in sampling. The manager realizes that experience, tests, preliminary studies, etc. all lead to knowledge about a population. They rarely have time, money, resources or enough diverse situations in which perfectly designed studies can be done. Observing in the field is sampling. Knowing how many samples are really needed to draw a conclusion at a stated level of confidence and within acceptable limits of accuracy can have a very conservative influence on an observer. It can produce anomie; the manager may never be able to make enough observations to be confident enough to make a decision and act on it!
Take the situation in which the sampling equation is used:
n = s2t2 / d2
and n is the sample size needed; s2 the variance in observations based on quick preliminary analysis or reports from other observers; t2 the Student's t-test statistic taken from a table. Within t is expressed the level of confidence. Assuming at least 20 samples will be taken, then the value for t, when the confidence level is about 95 percent, is 2.08. When 80 percent, then t is 1.33. Look! The value 2.08 squared is 4.3 and 1.33 squared is 1.8; the one is 2.4 times larger than the other ... and so must be the value of n, the sample size. Nothing physical changed in moving from one value of t to another, only the manager's decision about the confidence level. The value of n increased and so did time, costs, processing, data analysis, data entry, etc. As suggested in Chapter 3 and 17, perhaps winning 51 percent of the time is all that is really required of the successful manager. At the 50 percent level of confidence, the value of t is only 0.69 and t2 is 0.47, about 10 times less work required in a managerial study than required if a level of 95 percent is insisted upon. When drugs are to be administered to humans, and we might be one to whom they are given, then we tend to think that a level of 99 percent or higher may be a good idea. When setting a squirrel hunting season or applying water to a wildlife food plant nursery, must the confidence be so great? If you personally are paying for the study?
The probability of being in error about a conclusion, this level of confidence (variously expressed as 90 percent or 0.10), is only one among the decisions to be made by the manager using the above equation. The other is the level of accuracy desired for the estimate that is being made. It is expressed as d2 and is "the mean plus or minus the product of some percentage."
d2 = ( Mean x a)2
In this case, a means a percentage divided by 100. If the mean value from plots is 200 grams and you are looking for very subtle differences, then plus or minus 5 grams may be reasonable (about 2.5 percent) (thus a = 0.025 and d = 200 x 0.025 and d2 = 25). However, if you are not sure about the wet-weight or dry-weight relations, know that the spring scale is of limited accuracy, that the clipping is to be done with 3 kinds of clippers, that it may be windy on the sampling day, and you are not sure of the care that will be used by all of your field staff, then plus or minus 20 percent may be reasonable (i.e., between 160 and 240 grams). Using this sample, what effect does a difference in alpha between 0.20 and 0.05 have on the number of samples needed. The relations: (200 x 0.20)2 = 1600 vs (200 x 0.05)2 = 100, or an increase of 0.15 in desired accuracy caused the sample size (whatever it was based on) to increase by 16 times! In using this equation for managerial decision-making, I encourage reducing the variance estimate, s2, by dropping outlier values if there are any, and dropping those suggesting a highly skewed distribution, using the 80 percent or less confidence level (t = 1.1), and using accuracy bounds of about 20 percent. The manager needs numbers expressive of the values near the expected mean, usually the median. The costs of thousands of samples dictated by such an equation with unreasonable confidence and accuracy limits should rarely be borne by the manager or those for whom they work. Statistical help needs to be sought and non-parametric techniques sought along with stratification and other techniques (Ackoff 1962).
Ownership and Access
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| Access can be combined with wildlife clearings, powerline rights of way, and alternative ownerships. |
Wright (1988) briefly reported on his study with Cordell, Rowell, and Brown on recreational access policies of individual landowners in the U.S. Average tenure of ownership was 23 years but only 38 percent resided on their property. The average ownership was 183 acres. If representative responses were gained, then 3.3 percent of the private, nonindustrial acreage in the U.S. is closed to recreation, 25.4 percent held for the exclusive use of the owners, and 46.8 percent open (with restriction) to certain others beyond the family. About 20 percent is open to the public.
Leasing and fee recreation have not increased; only 5 percent of owners lease any portion of their land for recreation (4.5 percent of the area). Forty-seven percent of the owners leased land for hunting, primarily (60 percent) for big game.
The relevant variables useful for study (as, for example, for entering into a multiple regression analysis (CAP71 and many commercial programs are available)) to discover the influence or role of owners in population size, rates of animal production, or reported user satisfaction are:
A somewhat rectangular management area of about 7000 acres (2800 hectares) has a perimeter of 111,420 feet (21.1 miles or 34 km):
There are other similar variables for studying ownership such as percent of land rented, with resident owner, corporate or family ownership, etc. The edge adjacent to the wildlife area relative to total area owned by a neighbor also suggests need for an expression of ease of working with neighbors, potentials for poaching, and the roles of other intensive beneficial uses.
Ownership of land largely determines whether wildlife will be managed or not; and, if so, then to what extent. Corporate owners and owners of large areas with substantial taxes may be easily convinced to engage in guild-like activity (Chapter 15). Other public lands (an enormous area in institutional land, rights of way, military, educational, unclaimed, abandoned mines, and other) are fertile areas for intensive forest faunal management. The private owner of a small amount of land (a majority in the southern U.S. being only 10 acres (4 hectares) each) is a very different problem. These people often take great pride in ownership, do not want intervention or second-party involvement in their use of land, do not want anyone "messing with their stuff", and know that decisions made for wildlife foreclose some other decisions later. They typically enjoy the freedom and knowledge of unspecified future options. Such freedom for future notions is a thing not quickly given away. The faunal resource manager needs to consider where to spend his or her personal life "coin." If influence on the resource is a criterion, then it will probably be spent in influencing a few individuals or corporations who own or control large areas of high quality land with minimum owners per unit of adjusted boundary (06). See Smith (1988).
On private as well as public lands, access means not only physical ability to get to and use resources but also legal and social ability. "Off limits" is well understood. For years hardwood supplies and growth have exceeded removal rates. There are many reasons for this. One notable one is that many owners of hardwood timberland use forests for recreation or other non-timber objectives (Josephson and Hair 1974:5). Denying such use or disagreeing with its propriety does not change the situation. Whether loggers want to cut trees for profits or faunal system people cut them for influencing certain animal species, makes little difference. The landowner holds decision power. They are likely to produce a tighter (than looser) timber supply in the future. The limits, the faunal system manager's constraints, will tighten.
Every tract of land acquired for or preserved for wildlife needs the rational scrutiny of questions such as:
Often the answer to questions 3 and 4 is yes, because it is possible to develop partial-area uses, to gain use during select periods, and to achieve land use control (Haigis and Young 1983) through:
Direct acquisition of land by a faunally-related public agency is one way to preserve habitat. This is expensive and may be prohibitively so or opportunities for purchase may be untimely. The Nature Conservancy, for example, a non-government organization, will occasionally purchase land for a government agency, then sell it to them, thereby jogging past the ponderous fiscal gait of such agencies that prevents them from acquiring exceptional land when it is offered.
The above list suggests options where land purchase is not feasible, where staff and acquisition resources are limited, and where social conditions prevent purchase.
In the U.S. there are at least 800 million acres of public lands that may be viewed as potentially manageable for faunal resource benefits. There are millions of other acres in military lands. Each state holds enormous area in rights-of-way, unclaimed and gift lands, educational and other institutional lands, conservation easements, and there are many others. Rights-of-way of utility and railroad companies represent vast potential areas on which the wildlife resource can be changed to produce significant net benefits.
The story about animal space becomes more complex because ownership can influence access to public or private forested land where benefits can be derived. A large, high quality public area with little or no access has low potentials for producing resource benefits. Wildlife, yes; benefit no. The Wildlife Management Institute (1984) reported hunter access to private land decreasing and since over 58 percent of all types of hunting is done on private land, the trend is of concern to hunters and agencies. The institute as others has listed reasons for posting being (1) bad experience of owners with resource users, particularly hunters; (2) apprehension about liability; (3) lack of economic incentives; (4) personal interest in property use for family and invitees, (5) trespassing and invasion of privacy, (6) littering, vandalism, and noise; and (7) fear of personal injury. Solutions advanced: (1) educating owners and users; (2) providing incentives (public leasing, tax payments, direct purchase of rights, etc.); (3) limiting or removing liability through insurance and state-level legislation (a model act is available); (4) providing cleanup; and (5) providing enforcement, especially rapid access to agents of the courts.
Forest survey data may be used to study the amount of commercial land that might be hunted intensively by making a plot of distance away from roads (Fig. 7.5).
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| Fig. 7.5. The distance of stands from maintained roads can be an indicator of potential human use. Forest or other wildlife roads have a zone of influence. Roads "cover" areas with potential use zones for hunting, observing wildlife, poaching, and eroding sediments. The green area at W must be removed as a contribution of the road; the area at the end (T) is an extra contribution of area covered by the road zone. Data from Michigan show how 85 percent of the forests are within 1 mile of a road (Spencer 1983). |
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Preparing an area-accessible map and analysis and allocating use rates and costs to this area may provide improved insight into the results of management. Change in total available area resulting from bridges built, fords created, or land acquired may be a good way to express the change per unit invested. Often active management cannot be done because working equipment cannot be gotten to the area.
Roads, like powerlines and other major developments, need to go through a two-stage decision process. First, there must be a decision based on demand. Is a road really needed? Once the decision is reached, then stage 2 makes sense. There is no best place for a road. All have impacts. The solution must proceed to evaluate "least bad" road location and design (Rasmussen et al. 1980 and Jones et al. 1986). They can be compared to each other but impacts of all of them will exceed the no-road alternative. The no-road alternative may be interesting to allow relative impacts to be seen, but it will be gotten at high cost. What will be done with the results? How are costs compared to a zero base? Can satisfying an interest be afforded? Comparisons among road sites need to be made after stage 1 is complete.
Gaining access is an important managerial task. It ranges from buying property (at least a right-of-way strip), to building roads, trails, and bridges. It includes working with outfitters to get resource users "back in" and out safely and with maximum experiences. It includes maintaining trails and camp sites; developing and operating aircraft landing points; and developing viewing points (because a person does not have to go physically to see an animal in a forest; it can be viewed or photographed, often better, from a nearby ridge or mountain).
At the micro scale, people can be taken by walkways and bridges high into the forest canopy to observe creatures there and can be taken stream-side or into river or lake-viewing facilities to view life there (such as manatees) at eye level. Glass-bottom boats provide access to underwater community layers just as boats and guides can provide access to coastal and riverine forests. Access can be evaluated as a percentage (of an area), as a probability (a function of rain, snow, flood, etc.) and as cost (including time-distance computations).
Access can also be analyzed in a manner parallel to streams in an area. That measure is called "drainage density" (total stream length/total area). Access can be tallied by type of road, then totaled. Harvest as a function of area road density would be an evident analysis. In a regression that shows
Harvest = a + b (Area Road Density)
then managers can attempt to increase or decrease the density of roads open to hunters in order to achieve the desired harvest. It is likely that an inverse relationship exists between road density (miles per square mile) and habitat effectiveness. It is essential to recognize that this relationship is life-group related, seasonal, and surely related to number of vehicle trips (by type) per portion of the day (e.g., during twilight), not merely road presence. (See CAP109.)
Changing density can be done by building new roads, but it can also be done by closing roads or road segments, providing alternative transportation for users, and, often overlooked, in regulating the time - days, time of day, and road condition - when roads can be used.
Kochenderfer (1977) found there were 5 ha per km (20 acres for every mile) of road in the central Appalachians of the U.S. where wheeled skidders were used. Where jammers were used there were 12.5 ha per km (1 mile of road per 31 acres). From this it can be seen that a manager's influence on equipment used in logging can influence achievement of faunal objectives. Roads and landings occupied 7.8 percent of the area he studied. This may be a useful statistic about wildlife areas just as is road density. It clearly relates to the area available for faunal production and for users.
Access is partially mental. A hunter anticipating success will only walk so far from a trail or road because getting a large animal out of the forest is not usually counted as the "fun" of a hunt.
The Hunter's Zone
The distance that hunters hunt or the distance that other users (or poachers) move away from roads or trails has had limited study. It is a significant factor. If it averages W, then 2W is the width of the hunted zone around roads (Fig. 7.5.) Areas beyond W from a road are not hunted or are so little used as not to be counted as significant (use is likely only due to chance) in any resource analysis (CAP22). Intensity of use varies as a function of distance from the center of a road and often other factors such as vegetation density and steepness.
The special hunt for the rare individual who hikes far into the back country away from everyone, the truly memorable experience, is not being denigrated. Rather, the management of faunal systems deals with populations of animals ... and people. Energy, usually limited, needs to be directed at the most people. Intensity of interest (value), expressed demand, and other factors influence allocating managerial effort. In some cases, special areas or seasons may be set for these abnormal people who prefer to hunt or use resources outside of the average hunter's zone.
The measurement of W can be done by tracking in snow, hunter reports, GPS location of marked kill sites, and radio telemetry of hunters. James et al. (1964) found that hunters took deer an average distance of 0.64 miles from roads.
A road or trail can be built and the manager may imagine that a use area "map" may be laid over a management unit, not just a new line on a map. CAP22 allows this concept to be explored, including how many miles of road are necessary to cover completely an area with a hunter zone of W which is probably unique for each management unit. Harvest information can be adjusted so that it is a measure of animals taken per unit area within the hunter zone (not just total forested area, etc.). (See "magic numbers" under population estimation, Chapter 8.)
With no field studies, preliminary estimates for the zone are possible. Knowing that a military forced march proceeds at 5 miles per hour, it is unlikely any hunter will move at this rate. But since it is maximum, then assuming an 8-hour day, then 4 hours away from a road and 4 out suggests a maximum zone width of 20 miles. This number is highly relevant in some western states and in many developing countries. A standard marching rate is 3 miles per hour. A more reasonable rate of moving is 2 miles per hour on flat ground. Thus the width of the road zone is 8 miles. If walking time is extended to 10 hours or physical limits set at 20 miles in a day for a person in fair condition carrying a gun, then a more reasonable maximum of 10 miles is gained. Hunting rates are not hiking rates so it is reasonable to assume 0.5 miles per hour, thus the width declines to 2 miles in and 2 miles out during an 8-hour day (CAP9070). It is thus no surprise to see a report of 0.6 mile. The distribution is like that in Fig. 7.5. Variable maps may results, with entire areas removed from the hunter's zone due to land posting, river barriers, steep slopes, etc.
The useable area is often much less than managers or the public realize. The remaining area distant from the road is a refuge imposed by human-behavior. Animals from these areas disperse into the hunted areas. If a road is proposed, then an area at the end of the road may be gained (shown as T in Fig. 7.5 as one-half a circle with radius W), but not immediately adjacent to the main road(shown as W) since this potentially hunted zone already existed. A road to influence hunting should be evaluated on the basis of area gains per dollar. Effectiveness would be judged on whether increased harvests or dispersal of users was an objective.
Hikers and resource users on horseback have almost unlimited access to parts of an area once they gain primary access. They generally stick to trails. Snowmobiles seem less limited and can be used to harass winter- stressed animals. They create a special problem for formulating rules, education, and enforcement (Jenson and Thorestenson 1972) in faunal areas.
Access is also related to knowledge of an area. There are dangers of getting lost, concern for not being able to return in time to meet party members, or concern about trespassing on private land or where permission has not been gained. The quality of a hunt or other wildlife resource use can be improved by providing well-marked roads, trails, and boundaries; providing maps; and in some areas requiring all users to watch a TV tape, automatic slide presentation, or short introduction to the area. Most managers feel tension about access for it can allow some populations to be disturbed and the extent of such influence is very difficult to measure. In some cases, animals avoid road zones and do not utilize the available forage there and reduce observation potentials. Roads may not influence animal behavior but result in increased poaching as well as legal harvests.
Disturbed animals expend escape energy, thus areas where escapes are numerous have lower net energy for populations than those on other areas. Feedforward considerations are a frequent problem for the manager. Whether to do intensive management in an area where future access is only anticipated or whether to work in areas already having access is a typical problem.
It is now possible to gain computer assistance for forest-road location (Jones et al. 1986) that minimizes foregone timber production, harvests the timber present, minimizes stream impacts, and creates a road system for future harvests and other resource use. Such computer systems cut two ways. They may say "there is no feasible solution." If the forester and faunal manager team gets such a message, it must not "force" the model. To live with a sophisticated model and aid is to die with it also.
With access roads and trails come silt. Roads can be valuable long-term investments or costly interminable problems. Roads have long ago been recognized as major stream silt producers (Burroughs and King 1989) and that effect no longer need come as a surprise. Minimizing costs of roads and minimizing the cost of sediment control follow the insidious logic of "do nothing." Minimizing sediment (s) does cost and the search is on for very effective control (e.g., no more than 2 percent (p) more than natural on-going forest erosion (e), (s < e (1.0 + p)). The road designer, considering the road as a permanent system, assumes at least a 30-year planning period and considers all present-discounted costs over that period. If steep slopes will have to be repaired annually and revegetation costs borne every 5 years, then these must be added into the project plan budget. Current forest managers, hardly out of the Biltmore era of influence, suffer under the maintenance load of poorly built roads. There needs to be a stop! The heritage of future wildland managers (or taxpayers) (or corporate land owners) must not be maintenance responsibility that saps their energies and budgets and leaves no room for their creative expression. The U.S. Forest Service now has built on its land about 10,000 miles of roads each year. See CAP23.
Considering mining roads, military operations, and roads being punched into private lands, the design, proper construction, and maintenance of these structures is insufficiently emphasized to faunal resource managers. In that a majority of the fauna of most areas has one life stage or key factor involved with a quality aquatic community, it is almost essential that faunal managers deal actively with the road system that influences water systems in a faunal management area ... and elsewhere.
The possible steepness of a road or trail is not simply a construction or mechanical equipment question. It is a question of energy costs to equipment (whether vehicles are used for logging or hunting makes no difference), hardship on equipment (direct as well as energy costs of replacement, safety, and down-time), and revegetation (the entire process from plan, to ordering seed, to final inspection, a tortuous path for such relatively small jobs). Just as costs of removing a rock outcrop in a proposed road corridor can divert a road to a less costly corridor, so should the calculation that, given soil type, rainfall, slope that sedimentation impacts, and regular revegetation costs, excessive potential sedimentation should divert a corridor.
Swift (1986) confirmed common sense in his study:
His equation for filter strip width along roads in the southern Appalachians is:
D = 43 + 1.39 k
where D is the slope distance in feet, and k is the slope (in percent) (Swift 1986). See CAP113 and CAP23. These are for sediment particles greater than 0.05 mm, since storm water runoff was muddied farther down-slope. Fines (particles less than 0.83 mm) rarely increase with logging. Doubling the D makes sense for it will accommodate most storms. The effects of the fine particles are often the most critical factors for stream fauna. Those effects depend on the faunal life group being tended but the road as a potential silt source is permanent and the storms are predictable.
Other guides for back-country road or trail building:
Creating "wildlife roads" is a technique used in some areas to allow below-value timber sales. After the primary construction cost is borne by hunters and anglers, the road may be opened to loggers. Timber, excessively expensive per unit of wood removed if a road must be built, becomes affordable after such roads are built with funds allocated to wildlife. Low-value sales added to high-value sales, some with and some without road building costs, can skew the net returns from a forest. The faunal system manager can count forest roads as desirable access. Similarly, he or she can be used as a ploy in a below-value sales strategy that circumvents a strategy of efficient, high-quality, intensive wood production on quality sites. Similarly, the "for unspecified wildlife" justification can get roads punched into areas where great resource benefits can be lost or destroyed.
The value of a road is the value of all future faunal benefits (at least game harvested) which would be accessed by the road or trail and all discounted to the present. The future flow of benefits is thereby accounted. Depreciation of the road value (CAP118), say for 40 or 50 years, in relation to net resource benefits from trees and/or animals is often a good comparison to make.
Roads are a mixed resource for the faunal system managers. They provide access to hunters but also poachers. They allow forest fire, insect, and disease control but increase the risks of these problems arising. Roads are a major managerial tool - for harvests (Boer 1990), observations, rescue, game harvest pick-up or assistance, stations or controlled hunting points, trapping, and research. See CAP22. They provide low cost access to study areas otherwise prohibitively expensive to reach. They provide a sampling transect for some studies, the places for scent-post studies (Chapter 8) and track counts. In winter they provide snowmobile access and opportunities to observe and feed wildlife. Although roads seem harmful to elk and elk-use of areas (Heib 1976), roads benefit some animals and seem neutral to others. Effects may occur where animals (or sign) are easily seen, not where they are most dense. They do provide energy-efficient pathways, visible zones, and special edge vegetation and associated insects. Pfister (1969) found that timber volume increased below roads in Northern Idaho forests. Site productivity increased because the precipitation falling on an out-sloped road was redistributed below the road and the unvegetated fills provided a reservoir during the summer drought. Above-the-road trees also increased in volume, presumably due to increased sunlight and space. He suggested that the product of road length and width did not properly reflect the productive area lost to roads because of these edge increases. Other options exist for positioning cuts to reduce the area disturbed by the roads and landings.
A road is a good example of a single project with one cost that influences many life groups differently, benefitting some, harming others, and being neutral to others. Only when demand, value, etc. for each species are analyzed can the net faunal benefits per unit of cost be determined.
Evaluating the consequences of building roads and trails on wildlife can be begun with a simple procedure such as shown in Table 7.3.
| Table 7.3. Gross analyses of the influence of proposed road or trail construction projects on individual species or life groups can be begun with a table such as shown here estimating net effects of each project. | |||||
| Species - Life Group | |||||
| Alternative Project |
A | B | C | D | Total |
| 1 | + | + | 0 | 0 | 2 |
| 2 | + | 0 | - | + | 1 |
| 3 | + | + | - | - | 0 |
Operability
Operability is an expression for an area. It is the relative ease or difficulty of managing or harvesting timber because of physical conditions in the stand or on the site (Spencer et al. 1986). Operability is influenced by accessibility, just discussed, but also by small average tree size, fragile soils, poor drainage, small tract size, and distance to maintained roads. Since the faunal manager may want to increase timber cutting to improve conditions for species needing young-age-classes, operability may be one factor to be influenced by the manager. Similarly, where old growth is needed for species, retaining inoperability may be the means to this end. For one area I studied, I saw on computer maps that large tracts and sites were inoperable for the above reasons including slopes too steep for the logging equipment in use. In effect, large areas of mature trees were assured for the future. The faunal manager would have appeared silly to advocate preserving mature stands; amounts far in excess of demand were already assured for fauna by the multiple factors of inoperability.
Boundary
A major managerial activity is to assure uncontested boundaries for wildlife areas, mark the areas clearly, and provide signs and other information to inform people about the rules for the area and potential uses. See CAP5005. Boundary marking and maintenance is a managerial activity encompassing concepts of ownership, control, and access. Since the minimum boundary (b) or perimeter of an area can be determined from
b = 2
(A/)0.5,
then the actual boundary (B) can be related to the minimum and will always be equal to or greater than
1.0 (B* = B/b).
Surveying paint, labor, and transportation and the recurring need makes this a high and often-ignored cost (CAP9071). Poorly marked areas seem to inspire trespass, vandalism, and dumping of trash. CAP144 provides a means to estimate size of timber removed by trespass or for other purposes. The stumps are measured.
Boundary marks are especially needed on leased areas and where fees are charged for area use. They provide users a sense of security, lack of fear of trespassing, and they reduce problems of unintentional trespass off of areas dedicated to faunal management.
Phenology and Time
That plants and animals vary with the seasons is not surprising. The manager needs to be a careful student of these seasonal changes, the phenomena. The manager must apply the results of each study. The emphasis may be on (a) protein levels in leaves and twigs, (b) secondary chemicals (metabolic blocking agents) present, (c) net energy in food (subtracting the energy costs of masticating and digesting the material), (d) presence of palatable food (insect-infested foods may not be eaten), and (e) shifting feeding behaviors (e.g., from carnivore to omnivore).
The manager needs to measure habitats or animals when the phenological events are appropriate. Two examples suggest the possibilities.
Comparing animals trapped and marked between years is often done. Usually the question to be answered is whether there have been changes due to "treatments", the manager's work. If the animals are compared on the same date each year, say June 1, the comparison may be meaningless. The winter may have been long, in one year plants may have broken dormancy late; some insects may have been delayed, others advanced; available biomass may be very different between periods; costs of gathering energy very different; stage of lactation different. The differences are conspicuous to all who have worked afield, yet comparisons are made between solar dates. The option is to use phenological dates. Each manager needs to select 2 or 3 measures and use them collectively to express whether the season or event is X days earlier or later than a standard year (usually the year when records were first collected). Examples include: the date when the leaf of plant y reached 10 cm, the date of first bud break, the date of first leaf fall, the date the ferns first emerged, the date that q birds first migrated, the first date of hearing frog species X. By using several indicators (for they are often related but observations may not be conveniently made), the manager can decide when population events can be compared, when conditions are most equivalent. These observations are not simply to make a time adjustment but to allow the integrative power of plants and animals to be used by the manager to understand the complexities of the animal population in the natural, unique situation.
The second example is one limited to food supplies. A shrub produces ripe fruit on a date. It persists, available to wildlife for 2 months then insects eat part of it and it falls. The curve is shown in Fig. 7.6.
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| Fig. 7.6. The summation of the amounts of fruit of different species is present (each curve represents weight of fruit for a species) can show total available foods in each year, possibly influencing animal productivity and survival.Herke and Rogers (1984) show similar seasonal curves for movement of estuarine organisms. |
Several fruits of different plant species are produced during the year. Some are available for short periods; some will last several years. Some plants ripen early, some late. Birds that eat fruits may not be able to depend on a constant or sufficient supply of fruits each year. They migrate. Others that are year-around residents may have adopted omnivorous feeding habits. By studying the summation curve for all foods for a species, it is possible to understand why species abundances are limited. A major limit will be the low point on the forage curve. This number can be communicated to people who see abundant food at some period and want to know why wildlife is not abundant. This information can help balance expectations with numbers actually present. The wildlife manager, seeing the low point(s) in the annual curve, can add fruiting plants or even feed animals during this brief period to cause the total curve to flatten. Fruiting plants can be added by getting them from a nursery or by other techniques such as preparing a seed bed and placing a perch for birds in the middle. Birds may sit there, defecate, and seeds in the feces will be deposited and produce fruiting plants.
It is evident that fruit production can be increased by managers but animal populations, if their food is limiting, will be limited to the period when the sum of that production is smallest. From one point of view, almost all fruits produced above this low amount are wasted. The money, work, and land could probably be better allocated by the manager.
Planning in faunal systems work requires a look at a horizon of over 50 years. This involves the annual differences discussed, both seasonal and phenological, but also longer periods. One study showed hard mast (acorns, etc.) to be a function of cumulative precipitation over 4 years. Deer production is a function of doe health 2-years previous. Shrubs bear fruit many years after planting, trees even more. Time is a dominant factor in faunal systems work.
The average production of mast (fruits) in any year is not the manager's key statistic. The annual production is not normally distributed. There are usually a few exceptionally productive years inflating the value of the average. The median is a more useful measure; the statistical distribution of values needs study.
Managers need to be very aware of what happens in present discounting the costs of fruit and forage production and using estimates of benefits over long periods. After about 25-30 years, the discounted value is very small. There is no real difference in results after 40 or 50 years; values are meaninglessly small. This is a phenomena of discounting, irrelevant to ecology, but of extreme importance to the way decisions are made in the financial world. I propose discounting time. See also CAP5003, CAP99, and CAP2029. One result of present discounting is that the planning period for faunal space managers becomes "as long as possible" because productivity or payoff, say from a planted fruit tree, begins years after planting, and then it is annual.
Faunal system managers are prone to plot animals or production over time. The implication is that animals are a function of time. All of the phenomena of a year, as in some mysterious black box, result in animals. This simplification may be useful for some purposes and for short periods, but it will eventually fail. Modern managers will try to develop models that have the same dependent variable but will have (a) the initial condition, and (b) major influential factors as independent variables. Thus, when one or more factors change, the manager can explain the results, not be victimized by a trend analysis. See CAP110, CAP84, and CAP152. Time does not "do" anything; it has no functional relationships in habitat or population analyses. It is a code for expressing an observed sequence or sequence of summations (e.g., cumulative solar energy) in other phenomena of faunal spaces. See CAP114, CAP162, CAP623, and CAP625.
Physical Space
Cover is a word now used so long in wildlife management that it is difficult to think in other categories. Cover is a gross expression of forest structure, but much more. See CAP9073. The concepts under the general umbrella-word are as follows.
Forest type (Eyre 1980) and age of stands can be depicted on maps. Stands are areas that have conditions that appear biologically uniform or homogeneous to humans and likely to be treated uniquely. Stands typically have tree age differences less than 20 percent of the length of the expected years in a harvest rotation period. Such appearance usually produced by dominant trees, probably is of little meaning to animals. A few species only occur in one forest stand type. Most are associated with several types of age classes. In a 1977 inventory in South Carolina, for example, 30 percent of timberlands were in stands smaller than 4 ha (10 acres) (Knight 1978). Thus, owners achieve very poor economy-of-scale for wood or wildlife production and hold insufficient size units for many wildlife species. Stand maps are two-dimensional representation of faunal space. They are rarely very accurate because aerial photography needs adjustments, edges are difficult to decide, and the width of a line used to mark areas on a map can represent a zone 5 to 20 meters wide in the field. These have been called "cover maps." They depict the top layer of forests.
Land is where trapped solar energy is stacked for fauna. A deer may not be able to eat a "two-by-four" but plenty of other things can. Things that eat wood are herbivores; detritivores and even carnivores are only second-stage herbivores. The faunal manager needs to be largely concerned with stacked energy, i.e., biomass. Because managers are usually species- or life-group-specific in their interest, they usually want to know what proportion of the biomass in the area is in species X of age Y and in layer Z.
Forests have layers (Fig. 7.7) and animals respond to layers of space (Angermeier and Schlosser 1989; Short 1984).
 |
| Fig. 7.7. There are many layers in forests useful in faunal analyses. The "tree bole" is an anomaly in this concept for it may be a part of the subsurface to canopy layers (CAP9057). It needs separate analysis as well as analysis with the volume in each layer. These layers (some may be missing) are used in feeding (including water getting), breeding, and resting (hiding, etc.). Figure from Giles 1978 with permission. |
Briand and Cohen (1987) observed that multilayered systems have distinctly longer food chains than single-layered communities and Short (1984:7) showed more guilds occurred where there were more layers.
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| Much effort and some danger is associated with work with fauna in the upper layer(s). |
Clary et al. (1968) developed regression equations for the floor of ponderosa pine forest showing herbage yield as a function of the litter layer (unaltered organic matter); a duff layer (partly decomposed organic matter); and humus layer (well-decomposed organic matter). Yield was inversely related to the depth of all layers (CAP9066).
Combined maps of forest layers, three-dimensional computer maps, will help managers, eventually, to understand species diversity in forests and help to explain differences that occur in the coefficients in species-area relationships. The species-area curves or abundance-area curves do not go through zero on the species axis. There is a minimum area (volume) of conditions that is essential before birds or other groups can exist in an area. This minimum-area notion is said to be a concept of "landscape ecology" (Forman and Godron 1986).
Complicating estimates of the real importance of area (stand or patch size) on animal presence or abundance is the influence of connecting habitats. Once called "travel lanes", these thin forest stands, now called corridors, are different communities, strongly edge related, and as much a function of contiguous vegetation and conditions as conditions within the strip. Their name connotes travel or some intermediacy between the "real" communities. They are travel lanes for a few species. They have unique characteristics and are worthy of separate investigation. They may be similar to a contiguous stand and may add life-group-specific area to it. If that total is sufficient to meet the needs of one or more pair of a species over the long run, all is well. If a population in another similar community is limited by a contiguous thin community, this is not surprising. Having a set of conterminous areas that meet annual, multi-year needs is the life-group criterion for presence and abundance.
Corridors may be travel lanes for a few species but most are so small (short) that the distances are not barriers to most animals. There is little evidence for real travel for many species. Most have small home ranges. The evidence is that species live in these thin strips, move around in them, but rarely use them for travel. A raised highway across a swamp is certainly a place that any moving animal will use. Is a corridor where observations of animals are increased? Corridors may enhance the flow of genetic material between dissimilar areas but that may not be desirable. Thin strips may serve as avenues for fire, disease, predators and human disturbance of nesting animals. The corridor bandwagon has square wheels.
Of course, an inconspicuous way for an animal to move from one resource to another is important. It does not have to be viewed as narrow; it may be a ditch. "Distance" is also a type of cover. The shorter the distance, the less the risks and energy expenditure required to move between places. For example, a water supply may be present within the home range of an animal but the quality of that space can be influenced by the number of water development available, their spacing, and movement required from other resources such as mast crops, dens, and summer fruits. Creating a supply is the first step of management; then (or simultaneously) is the need to assure the highest reasonable utilization of that by populations over time. Often, major improvements in space quality can be achieved at no additional (or less) costs compared to a positive effort to increase the number or area of wildlife spaces.
Forest space has many temporal dimensions. Night is the profound cover for most animals. Twilight and night lengths, seasonally, are the first-order measures of faunal cover (CAP109 and CAP114). Lunar forces on faunal presence and abundance are yet to be described (CAP147). A stand today is not the same stand 5 years ago. Layers change, phytomass changes. Interpreted as tree growth or yield, or as ecological succession of stages, change is a stand reality. Animals respond as much to forest age as to type. They respond to plant size more than age. Birds, for example, need sufficient nesting sites and bark area for foraging. They probably care little whether the bark is white oak or red oak, old or young, only that it is bark, will hold their weight, and contains insects. Of course some trees have more insects than others. Such knowledge is a modifier in the quality of the age-related structure of the forest.
Area between forest layers is horizontal edge. (The human mind-set is for vertical edge.) The approximate index to relative horizontal edge is:
EH = 
areai (layersj + 1)/Area + 1
where each ith stand has j layers and these are compared to the total area (for all k stands) of the compartment or forest. This may be made more precise by weighting the relative goodness of the contiguity of each layer for each life group.
Thus, the stand has area (of two dimensions), layers representing a third, and age of each layer a fourth. Areas occur at an elevation, thus a fifth. Elevation has associated with it many phenomena such as barometric pressure, temperature, and even latitudinal similarities. Each spot receives different sunlight as a function of latitude, cloud cover, and topographic shadows. The space for fauna is n-dimensional.
In systems work, equifinality is an important concept. When there are many factors at work, it is possible to get the identical results from several combinations of these factors. The faunal system analyst must always consider equifinality. It usually prevents a clear relationship being discovered for a forest phenomenon. Instead of "if A, then B", the relationships are "if A or D or E x F and <G, then B." Several different system operations may produce B. The concept allows higher managerial risks to be taken but it explains why strong conventional regression models are difficult to obtain.
Trees intercept rainfall, thus reducing precipitation pressure on the thermal shell which exists for each warm-blooded creature. Rainfall is usually cold and an energy drain; evaporating, its result is also an energy drain. Fauna need access to protection from precipitation. This protection has been called cover.
Similarly fauna need protection from wind. Forests can reduce wind velocity, but velocity is a function of stem density and topographic position, and thus a layer-specific phenomenon. Convective heat losses from animals can be extreme when wind and moisture are combined (Moen 1973). Evaporation of 1 gram of water in the winter results in loss of about 590 kilocalories of energy from an animal. This much less energy must be replaced by foraging if a balance is to be maintained. Because of second-law losses which occur when energy changes form, evaporative energy losses can cost an animal dearly for replacement. The interactive temperature, wind-velocity, and moisture subspace is of great importance to the surviving productive population. Dealy (1985) with Thomas (1979) described how a concept of an optimum condition for a life-group could be expressed as forest canopy closure (Lemmon 1956). Such closure seems related, intuitively, to these notions of energy budgeting and thermoregulation. Crown closure (C) has been related to basal area (B) in many forest types. Thus, from standard basal area (prism) measurements, closure can be estimated and thus an index to habitat suitability for a species determined. If 70 percent closure is optimum, for example, for some species-group, then stocking rates and thinning can be adjusted to achieve a basal area likely to provide it. The form of an equation useful for determining area and type-specific equations is
log10 (C + 1.0) = a + b log10 (B + 1.0)
See CAP9072. The manager seeking to reduce populations (Chapter 13) will find this space easily utilized by simultaneously increasing wind velocity or moisture when the temperature or moisture relations will be harmful to a pest population.
Forest faunal managers realize that fire, grazing, or recreation-user trampling can reduce "surface roughness", the manageable factor in influencing surface layer wind velocity. Restricting use, erecting baffles (e.g., snow fences or earth mounds), or underplanting can be used to reduce wind velocity.
Winds at the edges of stands where clearings have been made pose special problems. Winds can reduce moisture and lower site quality and cause moisture stress with secondary insect outbreaks. Careful layout of wildlife clearings or forest clearcuts (shape, size, and orientation) are needed to maximize edge quality, minimize site degradation, and minimize secondary forest losses.
Cavities, dens, and burrows are needed by fauna for improving their energy budgeting as well as nesting. Animals need protection from all of the elements, from predators, and from members of the same population seeking identical resources for survival. Cavities increase with tree age; cavity formation is tree species related (generally the less the specific gravity of the wood, the more cavities); cavity duration is also species related (but directly related to wood density). Cavities can be preserved by protecting old trees. There were an average of 25 per acre (55 per ha) in stands of the Sierra Nevada (Jimerson 1989). They can be created in trees by drilling holes and inoculating the cavity with wood consuming organisms. They can be created by carving out a cavity then nailing a board with an appropriate-size hole over the excavation. Limb pruning of some trees (e.g., sycamore, Platanus occidentalis) will produce cavities. Snags will be used by woodpeckers and other fauna to create (or hasten) cavities. Snags can be created by axe frilling (cutting through the cambium), herbicides, or blasting the top out of trees (Bull et al. 1981). Some species of woodpeckers forage more than 70% in winter on snags (Brawn et al. 1982). It may be possible to specify a desired number of snags per hectare (e.g., 5 to 6 in ponderosa pine stands, 3-4 in eastern hardwoods) but such expressions are made without attention to faunal demand; risks; present inventory; home range; the select species group; tree size, age, or species; profits foregone, or alternative practices not implemented. When objectives are poorly articulated, it makes good sense to attempt to retain many snags in forests. Cunningham et al. (1980) found that snag presence accounted for ("explained") more than half of the variability in the number of secondary cavity-nesting birds in coniferous stands. These birds use cavities created by woodpeckers. Cavity use is greatest soon after a tree dies. The better cavities are lower in the trees. Trees or limbs must be large enough to contain the cavity space and insulation. As in feeding, many species are opportunistic; they will nest elsewhere if snags are lost or removed. Some require them. Many migrants return to their natal areas and use the same nest areas. They may be imprinted to area characteristics. Imprinted information about nesting success is negentropic for populations. To achieve potential species richness (if not abundance) then snags must be present in the managed area. Nest boxes can be readily built and they will be used by many species. Brush piles, log dens, even rock dens can be built and many will be used. Encouraging some mammals that dig burrows may be useful tactic in some areas. These burrows are invariably used by other animals, sometimes simultaneously. Soil and geologic strata influence whether burrows or dens can be built or will last. Thus the energy "worth" of a den is a function of these factors. I believe that in second-growth forests, lack of cavities, nests, and "home-sites" limit many forest populations for the long run (e.g., 20 years) more than do food supplies.
To manage trees for cavity nesters misses the point of managing snags (Brawn et al. 1982). Snags provide cavities and places for cavities to be created. They also decay at predictable rates (succession). They provide a foraging area (CAP9057) for some species that is probably at least as important as the cavities. The species of trees can be expressive of bark or surface roughness (thus total area), the more rough the better for insects, thus insectivores. There may be chemical and other differences in bark-wood-insect relations. The manager for bole-feeding fauna can ignore such a subtlety and have an objective of stabilizing a very large, high-quality (a roughness index) dead-tree-bole surface area over a large management area.
Resting spaces are needed. Stress on how much food animals need can lead to misconceptions about their behavior. At least seasonally, and in many areas, food is readily gotten and there are long periods between feeding events. There are extensive periods for "lazing around." Disturbance by recreationists, loggers, etc. can disrupt these periods, prevent grooming, digestion, lactation, and energy conservation and storage. Physical barriers to people can prevent disturbance just as can area closure. Enforcing a closure can create resting cover, a most peculiar act of "habitat management."
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| After fire and grazing, understory may be sparce and major work needed to restore a profitable forest. Retaining mast-producing and nesting, and roosting trees while favoring select understory trees (cost effectively) is almost impossible. |
To flocks of birds, packs of wolves, nestlings, or herds of deer, adjacent animals offer protection from the elements and offer extra information about the environment. Animals are as much, if not more, a part of the relevant environment to an animal as a shrub or tree bole. Animals are "cover." They are part of faunal space.
Animals need places into which they may escape from predators and hunters. These places are important, partially because of their presence, partially because of animals' knowledge of them. Escape areas are highly valuable to old animals of long-lived species. To the young, such spaces provide little advantage except by chance use. Where vegetation and terrain offer abundant escape spaces, knowledge is not important. All animals live where "escape" has already occurred. They live protected. They survive in some areas, fail in others. Escape cover may be lateral or vertical (as from avian predators).
Protection is needed from hunters and poachers. Lyon (1987) developed a program called "Hide2" which expressed the distance at which animals can be seen given the density and diameters of trees. (See also Canfield et al. 1986.) Lyon (1987) based on Thomas (1979) said that "hiding cover" for elk is provided when vegetation hides 90 percent of an elk at 200 feet. Thus vegetation must obstruct the line of sight between an observer and an animal in a block that is sufficiently wide. Their public-access computer program provides insight into effects of timber growth, harvest, or understory development.
Visual barriers or cover along roadsides can deter poachers but prevent desired viewing of wildlife by people viewing from cars. Visual barriers can be developed from food-producing plants so several objectives may be achieved at one cost. As always, the use of vegetative visual barriers depends on local objectives and alternatives available (e.g., closing or restricting road use at night).
There are few good techniques for estimating the density of cover. Basal area is one gross estimate; stem density is another related variable. They should be used as separate variables in multiple regression analyses of their relations to animal sightings, signs, or density estimates.
I fear that cover boards or panels (measures of the area of a standard grid or survey road that are blocked from view by vegetation) are inadequate. (For example, 10 percent of a board's top cells blocked by vegetation is rarely equivalent to 10 percent of the bottom cells blocked.) I prefer measuring the distance that a person must walk (dragging a tape or pacing distance) before he or she (or a carried panel) becomes 95 percent or 100 percent obstructed from view. The distance is inversely related to vegetative density. Percent of area covered by grass or forbs (viewed from on top) probably relates as well or better than lateral estimates of understory vegetative density.
Ivlev (1961) suggested a simple index to how animals elect to use a particular type of cover. It is
E = (r-p)/(r+p)
where r is the proportion of the cover used, p the proportion of available cover. The index ranges from -1 to +1 where -1 is avoidance and +1 suggests strong selection of the cover (CAP9073).
Animal "cover" is varied and has many dimensions. The largely unrecognized cover is the night and twilight. Night is the most profound cover. Understanding lunar forces will one day be recognized as important. Cover changes annually and with succession. It is as important as food; there is no need to decide which is most important. Both are essential. A population must balance its energy budget. Losses or gains, the coin is the same ... kilocalories. Most cover dimensions are those of protection - from precipitation, predation, etc. The major need is for managers to protect and improve quality faunal spaces, at least to begin using the concept of faunal volumes.
Trails
When an animal does not have to be alert, to spend energy, as in an open environment, it is in a favorable space. Costs to animals are high of stepping over branches, wading through deep snow, or climbing steep banks. Young animals, wet from ferns and grasses, are cooled nightly by evaporation. All of these energy costs must be met by equivalent forage energy. Energy saved is energy not used.
Margalef (1968) suggested that burrows, trails, and cavities are embodied energy, parts of animal space that allow the population to get or retain energy at minimum energy costs - ability to do the work of populations, i.e., balance an energy budget and reproduce.
A closed forest canopy is a tight transportation network to arboreal species. Patchy canopies limit ability of squirrels and similar animals to move within the upper layer. Firewood collectors remove ground-layer wood, the "highways" for mice and chipmunks. The cost of running over a leaf-strewn forest floor is more than that of a race from branch to fallen-log over a similar area. At least it is clear that the animals' speed is different. Perhaps few care. The manager of raptors, interested in increasing them, would attempt to increase forest rodents. To increase rodents is to make areas optimum for them - areas where food energy is abundant and the costs of living are low. Making rodent "trails" out of logs and branches(triangulation) is a technique. Lack of them after a forest fire explains some limits on fauna in these systems.
Animals will follow trails. Managers need to consider trail work on intensively managed areas (perhaps partially in cooperation with recreational use interests, but not necessarily) to get animals to go where they are wanted, to avoid areas where they are causing erosion at stream sides, to utilize available foods, and to avoid hazards (e.g., blind spots at road crossings). Of course trails can be used for counting tracks, monitoring population activity, and for observing trends.
Thomas et al. (1976) found that the presence of trails for hunters significantly influenced hunter use of forested areas and was among the least expensive techniques available for influencing hunter-game contacts.
Wet Places
 |
| Bulldozed ponds can provide a variety of environments for forest fauna as well as drinking water in critical periods and watershed enhancements. |
A "seep," an area perpetually wet within a forest, the show of ground water, is "of the forest." It is a special community. Water and temperature are the factors that cause it to be different. The difference itself is manifest in plant richness, invertebrates, creatures needing water only once in their life history, and frequency of occurrence of other terrestrial forms in the area. Seeps are usually small, less than one-tenth hectare, and have characteristic vegetation, often evidently unique because of moisture, shade, and soil relationships. These areas often provide essential spaces for amphibians and insects, snow-free animal foraging areas during the winter, over-wintering areas for some forms, "tonic" spring time food plants, and, of course, water. Abundant in some areas, all of them cannot be protected, but where they are few, these special spaces need protection. If for no other reason, they need care, because they are the places where the land speaks of its groundwaters - their abundance and long-term changes. Managers will study them more than in the past because of their contributions to richness, variety, and abundance of prey and a new realization that they can produce thousands of enjoyable hours for a growing number of people who find them fascinating, who find them to be special sites for a variety of reasons. Some people will visit them for their dynamics; they are often very different in each season. Some will have "adopted" a species of salamander that is found in them for continued study. The seeps are "their" places. There are people who seek special plants or groups of plants, a frog, or group of frogs. Hunters will relate well to wet places because of the frequency of their use by wild turkeys. They are now managed in some areas, but more can be done to make them faunal-resource-benefit-generating volumes.
They are readily changed by tree harvests. In some cases, the reduced transpiration and soil compaction increases water runoff and converts them into springs which erode into a channel and the formerly broad, wet area dries out. In other areas, after tree removals the evaporation is so great that the site disappears.
Not only because of the importance of seeps to the faunal resource, but also because of their value to the tree resource, should they be carefully studied and usually protected. They diversify the stand canopy, display root water sources, suggest proper species for regeneration, explain failures, and improve estimates of site index in previously harvested stands.
In some areas it is feasible to place a small plastic pipe into such areas, divert a small amount of water to a trough, and thereby protect the seep from trampling by animals and simultaneously provide drinking water throughout the year.
Bogs, ponds, and small oxbow lakes seem akin to stands in the forest. They serve as hydrologic features and influence the microclimate of nearby trees. They are also the special areas for many fish, for fish and other organisms as prey, and for a variety of life-groups-from kingfishers, to bats, to nestling wood ducks.
Moose or deer feeding at the edge of an expansive wet grassland cause difficulties for the forest faunal space analyst. Are the animals part of the forest or should they be dealt with under discussions of grassland and wetland ecology? My view is that from the forest edge there is a species-specific zone of influence, one determined by animal behavior, that is as much a part of the forest as the trees themselves. Without the biomass support of the grassland (usually enormous) of the animals, the stand of trees that exists would be very different - because of the animals. Deciding on the subsystem boundary is difficult, but, where possible, it should be done by the animals themselves. Radio telemetry, aerial photographs, rangefinders, tracks and gross estimates can all be used to establish the width of the wetland zone to be included.
Built channels and straightened streams have drained many wetlands. The water table has been lowered. Tree harvests have reduced stream debris, thus have allowed increased stream gradient and velocity and deepened channels. Some forested wet areas have been drained and the dry sites now have expansive cropland or pine forest stands. Balancing all resources and the sum of their benefits is a major social and public issue. Wetlands are important to many people "just because." They are said to have existence value. They should be preserved for the same reasons that some buildings and art and museum pieces should be preserved. Unconvinced, others argue their importance as future options. This is the argument of the speculator or the person buying a membership so it can be used when the time is right. Either may be sufficient excuse to encourage wetland protection, but others reject such claims. Then the arguments are left to their role in storing useable water, retaining flood waters (measured not in gallons but foregone flood damage), storing usable nutrients, slowing decomposition, providing faunal sites and support, and offering recreational opportunities.
Wet areas can be created but, these are usually of singular design - the pond, lake, or stream. Natural wet areas are highly varied; each is probably unique. The losses of such areas (e.g., estimated to be 80 percent in Indiana) represent one of the better examples of how site-specific work projects without feedback can allow a resource to disappear. No one person is at fault; the available resource seems great. Losses accumulate; no one is in charge of the inventory or the cumulative rate of removal. See Chapter 16.
In order to comprehend water needs for forest fauna, managers need to include time in their thought about animal space. Animal space is both temporal as well as spatial. Most animals do not need much water to drink. They get it from succulent or wet vegetation, dew, or body fluids of prey. I have lived with this generalization for years and only recently have learned that it is almost meaningless. All animal populations (2 or 3 exceptions do not deny the rule) need large quantities of water to drink at least once in their lives, not even every year. Such an awareness can hook the manager to the dynamics of forests, long periods of drought, streams that go dry with residual pools outside of every animal home range or territory, periods of low food intake, periods of sickness and dehydration, and periods when lactation places extreme demands on female animal water balance. Abundant drinking water may not be needed ... except for 3 days in one year of a 3-year life. Without it, large numbers of animals can die or perhaps large numbers cannot be produced. There is little difference ... only one that is seen in the eyes of the animals. Water is needed and areas need to be analyzed for water presence, weekly. Management can then meet the deficit by water developments - lakes, ponds, tanks, spring development, and partially-covered pit containers called "guzzlers" (Yoakum et al. 1980:369).
Most managers will be surprised at the number of faunal life groups that have a water requirement. List all fauna; the fish are evident but usually provide a larger list than usually expected. The insects and invertebrates having an aquatic stage are numerous. List all toads, frogs, turtles. Then list the water-related birds - ducks, grebes, gallinules, the waders, then some swallows, kingfishers, and shore-feeding birds of prey. In the wet areas of the boreal forest, over half of the North American waterfowl breed. Then list the mammals - muskrat, mink, etc. The list is often surprisingly long. For the forest faunal system to ignore or discount water is traceable to a "game only" emphasis, avoids the full meaning of prey management, and discounts the importance of long-term stable water supplies.
Water limitations are notable at every bird bath. The limited areas of bird "territories" suggest, first, the limited need for free (unbound or intracellular) water since there is not a water supply in all territories. It also suggests that the quality of any area is affected by its included or nearby water. Bird baths are an especially pointed example. Birds actively using them show the needs for free water in winter. "Need or desire?" is a classical question about animal use of a resource but one that hardly seems worth the work to answer it.
As always with management efforts, there is another side. Water developments may provide disease or parasite centers, may evaporate significant amounts of water previously entering streams or ground water, and may be areas of high predation. Ponds in streams can block sediment and nutrients to downstream communities. Feedforward thus discloses the need for ability to rest-rotate shoreline sections, to move tanks (or divert the water intake between 2-3 tanks), and to have 2 impoundments with water control structures to allow rest rotation by periodically draining or diverting water from one of the ponds.
The zone of influence previously presented for roads is especially useful in determining how many water developments are needed and planning for their budgeting and construction. The distance that animals travel to water, W, can be estimated from track counts, pellet group counts, radio-tracking, direct observation, etc. This can be the zone width. A circle of this radius drawn around all permanent water will show the area "covered" with the water zones and that area left is yet to be covered by water developments completed and their zones added. Minimum number of water developments and stream zones to "cover an area" can be estimated by using an average size hexagon with "radius" W, rather than a circle. These "pack" into a map area with no gaps or overlaps. The number of hexagonal areas, the influence of water on the animals of an area can be estimated (Giles 1985) (CAP9076).
I once suggested putting carp fish in a forest pond built with wildlife funds for wildlife. I wanted a large, slow-moving prey fish for forest predators and later scavengers. My supervisor had other ideas; game fish were stocked! I still think it was a good idea, one consistent with the demand for food for furbearers in an area and the low fishing pressure received by small, deep-forest ponds.
Ponds, like other major wildlife area developments, can have a strong influence on user satisfaction. Failure to see animals or to kill one in a hunt is discounted as being a personal short-coming, not a manager's incompetence. "It is evident that the managers are doing all they can; it is not their fault if I am unsuccessful" seems to be the logic.
Vast areas of forests, once periodically or annually flooded, once provided habitat for many creatures. The nutrient-rich waters provided pulses of life. Land clearance as well as water diversions have significantly influenced these areas. Rivers have been straightened; the oxbow wet forests are gone or little-resemble the eroding banksides of the current rivers and streams. In some areas, human water developments may be essential to preserve the flora and fauna, even in small spots in these changed areas.
Management for tree-profit has not provided the quality watersheds for which many people have hoped. Although streamside protection zones have been long advocated, they have been resisted and there are few examples of their existence. In some areas, even these protected zones (not clear-cut) are re-logged to remove from them selectively the larger more valuable trees. The result has been that there are few large trees fallen across streams. That condition has resulted in increased sedimentation, increased channel depth, decreased ground water table, and reduced site indices on adjacent forested areas. The faunal system manager needs to take the perspective of being a ground water table manager. There is need to allow large woody debris to stay in streams, to form the original stair-step gradients.
Faunal system management, of course, includes fish and other aquatic organisms. Thus "wet places" include streams and lakes as well as ponds and seeps already discussed. The principles and concepts discussed throughout this book, I believe, all relate well to the management of stream fish and other stream fauna. Most would be repeated or restated for emphasis if a chapter or section on managing a fishery was included. There are many good reasons for including fisheries topics in a book heavily oriented to terrestrial fauna. I have resisted doing so in this book. One good reason is that many people employed to "do wildlife" must work in a role of "doing fisheries" (even though expertise even in one area is impossible to gain). Equally important, many terrestrial forms are related to aquatic systems. Resource users make little or no distinction: animals are wildlife. Seeing a beaver or otter enhances the quality of a trout fishing trip. Another good reason for resisting is the excellent forest fishery literature available.
Just as nitrogen fertilization and irrigation are primary management tools to produce more corn, so are forest harvesting strategies primary tools to produce stream fish. At least under the Multiple-Use Act, and certainly responsive to the demand level of a large number of U.S. citizens (more than there are hunters), there is a need for tending the stream fishery and probably producing more fish. At least no one advocates stream fish reductions! (Unless they have a harmful exotic.) Forest harvesting practice (or the lack thereof) is the primary means to stabilize or increase stream fish populations over the long run; forest faunal system management is key to maximizing benefits from the fish so produced.
Forest harvesting affects stream systems. The primary processes all vary and because there are so many, every stream is unique. Every stream "reach" or section is unique. The primary processes associated with increased wood harvests are:
For lakes, ponds, or streams, I know not where they start and the forest ends. As on the human face, where does the nose start and the cheek begin? The answer is a decision. This re-emphasizes the general system concept of context. A system is decided. "Today, here, for this problem analysis and action, the system is the water and the soil up to that particular high water mark, a column of air over it 500 m and a volume beneath it 500 m. No further discussion on this point! Now..."
All systems are subsystems. After analyzing a wet place, workers will probably want to expand their precipitation-generation system - but only afterwards, at a time when feedback says to do so. And, after that, they will probably want to expand it to include geology, solar radiation, insects ... then expand to include the region, then ... [This is an implication of the arrows in Fig. 1.2 pointing to "context."]
A green leaf, depending on species, provides abundant water to an animal that consumes it. Oven-dry leaf weight is about 40 percent of that of green leaves, 20 percent of early-morning dew-covered leaves. The leaf can be seen as a structural sponge capable of delivering water to an animal. I have seen wild turkey poults peck at a droplet of water at the end of a grass blade.
Another dimension of forest faunal systems work with aquatic fauna is that managing a"fishery" means managing a total system, an enterprise. The systems concept is already captured by a word. There is no equivalent "wildlifery," a total resource system.
The National Park Service, by policy having places for nature and minimum human disturbance of plants or animals, yet permits fishing. Faunal system managers, taught in universities the merits and sanctity of logic, consistency, and parallelism need not believe that violation of such university rules is evil. They are violated as well within as without the university.
Stocking of terrestrial game is typically discouraged on public areas. The costs are too high (for average taxpayers); ecological perturbation is thrown out as another reason not to do so. Loss of wildness (unmeasured) and genetic risks are other reasons. Stocking of fish, however, has been encouraged and massive production and distribution systems exist, federal, state, and private. The demand and preferences differ, the aquatic volume into which the fish are placed is more restricted than terrestrial volumes, the costs per animal are less, the returns are higher, and the tolerance of anglers for crowding is greater than for hunters. Carefully controlled stocking remains a key technique in providing animals for hunters on private hunting areas - often profitably.
The faunal system manager invariably works with watersheds as the context for data analyses leading to system control. Karr et al. (1983) called for a comprehensive, integrated approach to watershed management as did I (1962) and many others. (I now recant; cellular GIS work, typically 10 x 10-meter Alpha Unit work needs to be the basis for land use planning and analysis. Watershed analysis over-generalizes; it discards information readily available. Good for stream flow and sediment analyses, it is inadequate for the typical land use analysis.) What goes on in the upper watershed influences the faunal environment, the managed aquatic volume. Not to gain control of the watershed puts the manager in a perfectly dry cabin on a sinking ship. The forest manager must often seek off-site controls over zoning, market forces, land taxes, construction of dams or barriers to fish, use of toxicants, grazing, industrial or non-point pollution, and even stream crossings of logging roads. The manager must gain control over the stream or lake shore section of interest, the subsystem ...but then more. Perfect control of the on-site factors may be meaningless.
The controls needed, on- and off-site, include those over: (1) gully and land erosion, (2) loss of bed or bank material in the channel, (3) progressive deposition of sediments within channel segments, (4) migration of stream pattern (increase in the amplitude of the stream's lateral meander and movement of stream bends down the stream valley), (5) debris loads, (6) toxic substances, (7) nutrient enrichment, (8) flow rates and frequencies, (9) direct channel alterations (usually straightening) (cf. Skinner and Stone 1983), (10) introduction of exotic fauna, and (11) withdrawals (Karr et al. 1983). In general, when forest harvests are made following "best management practices," there are no apparent effects on fish populations. Where biomass or species composition in a stream changes, similar changes occur in upstream control areas.
The presence of natural streams, those not straightened or those not having obstructions removed, include:
Streams and lake shores cannot be separated from their terrestrial edge. This zone is called the riparian zone (Thomas et al. 1979). Defining the zone is a matter for the courts and the definition struggle continues. Brinson et al. (1981) observed that the amount of land subject to 100-year flooding is about 6% of the land in the U.S. (exclusive of Alaska) and that about 70% of the original floodplain forest has been converted to other uses. The lowland riparian forests may thus be "... the most severely altered ecosystems in the U.S." (Brinson et al. 1981). See CAP9056 for a unit on riparian preserves.
Sedell and Swanson (1984:12) observed that salmoid fish biomass was very much a function of the amount of light reaching forest streams. Streams with open canopies tend to be more productive of algae, thus herbivores, than do densely-shaded streams. There are succession-related trends in biomass of certain species. Care must be paid to other local factors such as increasing stream temperatures after opening. These temperature changes may be profound (as in egg mortality) or subtle and unexpected. For example, the competitive interaction between California stream dace and sculpin was shown to be mediated by temperature (Baltz et al. 1982). As stated throughout this book, a system can be analyzed and operated for a particular fish or faunal group. To do so requires, for example, manipulating the overhanging canopy, influencing exposure of the stream surface to light, and placing and maintaining large woody debris.
The water volume, part of the forest volume, has layers of distinctively different importance to faunal life groups. Fish and other organism live below the bottom surface of the water layers. They are an amazingly complex and difficult-to-sample group and are poorly known. Different organism depend upon particles of different size and type on streams and beach bottoms. Describing the sizes of particles and their distribution provides insight into potential fauna present and a major factor affecting them. Thomas (1985) described the complications in measuring suspended sediments and recommended automatic sampling devices, particularly during high flows. He emphasized the importance of planning, particularly the need for clear objectives for the results of the costly and difficult sampling and analyses.
Hayter and Mehta (1983) worked on a model for sediments in estuaries. Their observations emphasize the messages of this book (clear objectives, potential use, reasonable precision, balanced systems, practical and cost-effective modeling):
Probably the main "limitation" of a model arises from three sources: insufficient data, poor quality of data and limitations of hydrodynamic modeling. The first two sources are attributable to the fact that, owing mainly to time and cost considerations, all the bathymetric, hydraulic and sedimentary data required for use in such a model are rarely if ever measured and/or collected in the body of water being modeled. In addition, the quality of the data is often questionable... The third source is often the result of the first two in addition to the technical deficiencies in the state of science in modeling estuarine hydrodynamics.
| Table 7.4 Modified Wentworth particle sizes. | |||
|---|---|---|---|
| Name | Alternative Name |
Size Range (mm) with PHI Units (-log2) in bold |
Median Size |
| Mammoth Boulder | Boulders | >4000 | |
| Very Large Boulder | Boulders | 3501 - 4000 | 3750 |
| Boulder | 3001 - 3500 | 3250 | |
| Boulder | 2501 - 3000 | 2750 | |
| Boulder | 2001 - 2500 | 2250 | |
| Large Boulder | Boulder | 1650 - 2000 | 1825 |
| Boulder | 1331 - 1650 | 1490 | |
| Boulders | 1001 - 1330 -8 | 1165 | |
| Medium Boulders | Boulder | 831 - 1000 | 915 |
| Boulder | 666 - 830 | 750 | |
| Boulder | 666 - 830 | 750 | |
| Boulder | 501 - 665 | 580 | |
| Small Boulder | Boulder | 416 - 500 | 450 |
| 336 - 415 -8 | 375 | ||
| <304.8mm | 251 - 335 | 290 | |
| Large Cobble | Rubble | 191 - 250 | 220 |
| Rubble | 131 - 190 -7 | 160 | |
| Small Cobble | Rubble | 101 - 130 | 115 |
| Rubble | 65 - 100 -6 | 85 | |
| Very Coarse Gravel | >76.1 mm | 51 - 64 | 57 |
| Gravel | 33 - 50-5 | 40 | |
| Course Gravel | Gravel | 17 - 32 -4 | 24 |
| Medium Gravel | Gravel | 9 - 16 -3 | 12 |
| Fine Gravel | Gravel | 5 - 8 -2 | 6 |
| <4.7mm | |||
| Pea Gravel | Fine Sediments | 3-4 -1 | 3 |
| Very Course Sand | Fine Sediments | 1 - 2 0 | 1.5 |
| Sand | Fine Sediments | 0.062 - 0.991-4 | 0.5 |
| Silt-Clay | Fine Sediments | <0.062< or = 5 | -- |
Some studies show that what is on the stream bottom, the substrate particle size, is very important to fish. Others disagree. One cause for difference of opinion may be in the fish and their natural foods. Those that feed on animals that depend on large rocks, cobble, (220 mm median diameter) are abundant. See Table 7.4. Since sampling times vary, fish populations are dynamic and vary in a year, rocks change with varying water velocities, and rock surfaces are recolonized at varying rates, it is surprising that any studies draw conclusions suggesting common principles.
Sediment, usually particles less than 0.0625 mm, is probably the substrate of lowest value to organisms. For many stream forms it is judged to be a pollutant because it fills the spaces between larger particles. Within these spaces, eggs hatch and young fish survive freezing conditions. Sediment can cover eggs, cut out light, clog fish gills, cause some pathology, reduce feeding (obscuring prey), and scour vegetation. After noting this for fish in general, then particles become species related. Most aquatic invertebrates occur on the bottoms of rocks. Rock surface area can be estimated by the area of a sphere which is:
A = (0.56419/D)2
D being the diameter, and estimating the proportion used by invertebrates. The better stratified the bottom for sampling, sampling areas that are uniform and different, the less the variability and better the likely study results.
Dense cobbles, all touching, do not provide the same space for fish as many of the same cobbles widely scattered. Rather than analyzing the rocks, I recommend analyzing the fish space, the suitable water volume, and the surface area that "grows" the invertebrate food supply.
The layers of the water column suggest a vertical distribution of fauna. This is enhanced further by elevational differences. There is said to be a "river continuum" (Vannote et al. 1980), a series of stages or faunal communities characteristic of each part of a river and reflective of its age, depth, cross-sectional area, temperature, substrate, food available, and flow rate. Streams are classified into"orders," first being the usually intermittent or non-existing flow that once caused a dip in the land that is seen on a contour map of a mountain crest. Where 2 first-order streams start, there a second-order stream begins, etc. In the river continuum,"shredders" tend to dominate the upper woodland"reaches" or stream segments,"scrapers" appear most in intermediate reaches,"collectors" increase downstream. Predators are uniformly distributed (Hawkins and Sedell 1981).
The height of the water column is a function of precipitation and the other dimensions of the water balance equation. When dams are built and below-dam water flow is interrupted, it is evident what is likely to happen to the fauna. Irrigation, dams, mining, climatic change, intensive agriculture and forestry as well as inter-basin transfer of water (Cason 1980) have drastically changed flow rates. An entire field of study "instream flow regulation" has grown up (Orth and Maughn 1982, 1986, Orth 1987). It studies the water flows needed and criteria for water quality, dilution of pollution, navigation, recreational use, and hydropower. The flows required are not necessarily constant since some ecosystems are perturbation-dependent. Odum (1983) described the annual or periodic pulses of energy (e.g., debris for fauna), sediments, and nutrients.
The fish to be managed live in a volume of water. This has dimensions of length, width, depth, and time. Many fisheries studies only report area (length x width) because it is easily and consistently measured. I believe depth is too important, too influential in describing the habitat or environment to omit it. Most fish live in the zone of water which light penetrates. This is where the plants fix energy, small fish feed on plants, and larger fish feed upon them. This zone depth changes seasonally with turbidity and temperature. In analyzing large systems, the magnitude of surface area may overpower the factors operating the thin zone where light is king. This is a numerical problem, not an ecological one, and data transformation will allow improved understanding of the system processes. Some fish species, depending on the time of the year, use other parts of the environment for resting, foraging, egg laying, and escaping predators. Others respond to the temperature and oxygen, themselves forming a sub-unit of the water, a distinct, measurable sub-volume. Others compromise their own individual needs to continue to respond to the rules of schooling behavior and its survival values. Time must be included because stream phenomena are simultaneously sequential, or transitional, and conditional.
Because of temperature, dissolved oxygen, and turbidity, the actual volume of high quality or suitable water for a fish species (or group of importance) can be very limited. A change in turbidity can easily reduce the "good" volume by one-third to one-half. The manager, seeking to understand the factors influencing his or her fish population, will try to learn about the volume of the water body they manage. The area is mapped by conventional means or taken from photos or satellite images (excellent for studying all of the water of a region). Then detailed studies of depth are needed, perhaps mapped in a geographic information system.
The first need is for light penetration. This is determined from a boat. A white and black disk (Secci) is lowered slowly over the side at a GPS location. When it disappears from view, its depth is recorded. This gives a reasonable approximation of the depth of the productive zone. Computer programs can be created to process hundreds of such observations over a large lake.
Total depth of a lake can be gotten from old maps made before an area was flooded or from electronic devices in a boat, plotted, then total volume of these measured cylinders of water can be calculated. A rough approximation of volume can be gotten by assuming the lake has a regular shape like a cone or half sphere. A river with a large dam may be a half-cone. These provide rough estimates but can provide some "control," some reduction in the variability of studies as managers observe several lakes and streams and try to formulate general principles about their control and regulation. Water bodies as well as knowledge about them may then be subjected to corrective and additive feedback.
Some water areas are very circular. Others look like amoebae. The manager wanting maximum places from which people can fish with a pole wants maximum lake edge. A circular area provides the least edge per unit area. The actual edge can be compared to theoretical edge of an area, forming an index of circularity as used in terrestrial systems (CAP65 and CAP9062).
The bottom provides places for feeding, resting, and egg laying (and all may not have the same characteristics). Useful major insights into fish include the following.
Fish are like terrestrial animals in requiring relatively specific habitats. Some have very broad tolerances - they are found everywhere. Others have very narrow or specific requirements. Some are so specific that they are endangered because when those unique places disappear or when the conditions change, even a little, they are no longer suitable.
A fish species may be collected in a stream. It is usually identified and then a general description is written such as"common in the clear riffles of the upper portion of the river" or"prefers very clear water, rocky bottom, and moderate current." These are almost meaningless but they tell of humanly conspicuous and intuitively known positive relations of environment and animal. By concentrating on specific factors such as water current flow rate, size of rocks, percent of rock coverage, and temperatures, then requirement for a species can be estimated. Single factors can be useful to the manager but there are many conspicuous interactions in aquatic systems so they need to be considered together. The faunal space is full of corners, threshold, and curved surfaces. For example, a fish may survive well in a relatively toxic environment but if the temperature is increased, the two together can be fatal.
|
|
| Fig. 7.8. By observing a fish species in many streams or rivers and observing the conditions present (i.e., those described by factors such as maximum and minimum temperature) the tolerance ranges or limits of water suitability can be estimated. By putting many factors together (at least 3 like the one shown here) a box or space can be described. This is the beginning of the multi-dimensional space some ecologists call the hypervolume or niche. By studying the dates on which each limit is expanded (like the date on which knowledge about local flood depths are expanded), a theoretical limit can be estimated. |
The list is long (n factors) and the number of potential actions, A, or pathways that may be controlled is great:
A = n (n-1)
The number is so great that computers are often used to help in analyses and to simulate effects of changes on fish and other fauna.
There are many, many dimensions of managing a stream system for animals. Some aspects appear to be nearly self-evident but practices on the land suggest they may not be at all apparent. Destroying streamside vegetation, building steep roads, not using waterbars, clearcutting headwater areas, allowing stream pollution, dumping wastes beside or into streams - such ignorance, such disregard for future consequences and costs! Perhaps the more fundamental aspects of stream fauna management are esoteric and impractical in the light of such abuses. I can only hope that these gross land abuses can be overcome by techniques of behavioral change (perhaps education) and that the quality management now possible will not be masked by these asocial acts.
Quality management will address factors, for example, such as stream debris and the fundamental biotic processes of streams. In Oregon for example, concentrations of debris ranged from 0.9 tons to 26 tons per 30 m of stream channel. In Tennessee there were 13 kg per square meter (perhaps 4 tons per 30 m). Following logging, debris has been modified from 0.6 to 3.6 times the pre-logging amounts depending on the practices used (Swanson et al. 1976:2).
Stream organic debris is the assorted group of logs, tree tops, limbs, stems, roots, leaf mats, and whole trees found in streams. Determining the amount in streams is difficult because of the complexity, variety, and changing nature of the group of materials. Determining desirable or permissible amounts is difficult because of measurement and also because objectives are not clear: "Desirable for what organisms? People? Reduced sediment? Reduced risk if it should wash out?" To study organic debris in streams requires managers to consider the entire aquatic system. Fisheries biologists, stream ecologists, water quality experts, and road design and maintenance personnel would all probably set different standards for allowable debris. Much of the present indecisiveness about management of stream debris may stem from lack of understanding of the biological and physical functioning of debris in forested streams. Streams and their biota have developed through a long history of high concentrations of debris.
Physical characteristics of debris in streams vary systematically through stream systems. Debris loading is highest in small first-order streams and generally decreases downstream. In first- and second-order streams, large debris is randomly located where it falls because the streams are too small to redistribute it. Third- through fifth-order streams are large enough to redistribute debris, forming distinct accumulations which may directly affect the entire channel width. In the large rivers, large debris is generally thrown up on islands or on the banks and has little influence on the channel except at high flow conditions.
In the first- and second-order streams of the upland forests, there are massive amounts of detritus of the forest that fall directly into and are blown by wind into streams. The stream channel receives many times more organic matter than the average forest area because of gravity and wind and the great productivity of plants near the water. The processing of this continuous organic input with its periodicities and continual spike loads (e.g., ice storms) and depletions (e.g., scouring floods) is a system of complex beauty as well of significant managerial importance to local foresters, fishery managers, and downstream people with a variety of interests including fisheries, water quality and treatment, road and culvert maintenance, and safety. The ecological significance to the stream community is that, except for algae, this is the means by which fixed solar energy is input. Fixed on land, the energy enters the so-called heterotrophic community (Fisher and Likens 1973).
Once leaves and other organic matter enter the streams (and it is always "augmented" with dust and soil nutrients) they come to rest, at least temporarily, on rocks, branches, or logs. These barriers are very significant. Unless present, it is as if the stream has no energy input - it passes by so rapidly that it has little or no meaning, i.e., does not change the stream, and in most cases allows the speed-up rate to increase because its erosion-slowing role cannot be exercised.
Once dampened, then blocked, then the excitement begins. Changes start taking place. The excitement for the stream biologist is to name and understand the sequence and magnitude of the processes. Decomposition occurs and the four major processes are: (1) abiotic leaching, (2) physical abrasion, (3) invertebrate activity, and (4), microbial metabolism (Cummins 1974). The invertebrate activity is feeding and, in part, mechanical breakdown, equivalent to physical abrasion. I suspect all three occur simultaneously, say on 1000 leaves entering the stream in the same instant. Leaching of nutrients, at least from the surfaces, begins immediately, but is hastened as 2, 3, and 4 occur. Abrasion is a function of stream order. The lower the order, the higher the abrasion and physical breakage as parts tumble among rocks and over barriers. The mechanical abrasion and breakage almost stops upon blockage, but then animals, both vertebrates (e.g., beaver, raccoons, muskrats) and invertebrates (i.e., crayfish) become conspicuous breakers and stirrers.
At this stage the importance of the land animals, particularly beaver, to the stream ecosystems is very evident. Perhaps not equally evident is what happens when these animals are removed or are killed as the result of an application of toxicants on the land. The experimental removal of an organism from a wildland system in order to discover its function there is called an ecoectomy (Giles 1964).
Microbes colonize the wet detritus. Simultaneously the crayfish are beginning their breaking and shedding. I suspect these animals have a more important role than previously recognized but a role that remains to be tested. Some students claim that microbes must colonize first, providing the new"culture" that invertebrates shred and scrape to derive nutrition (Cummins 1974). The surface area is increased and more and probably different microbes colonize the new organic materials. The role of the microbial population needs further study (Anderson and Sedell 1979). As Fairchild et al. (1983:438) said,"the contribution of microbial populations is difficult to determine in the presence of invertebrates, epiphytic algae, and physical abrasion, which combine in complex systems of synergistic and antagonistic processes." There is succession in the microbial community (White et al. 1977) which can be altered by substances added or the local environment.
Fungi are even more important (from a volume-mass perspective) in processing detritus (Suberkropp and Klug 1976). Bacteria mainly process fungal excretions and dissolved leachates. Bacteria seem plant-specific.
Any structural change in the microbial community that adversely affects fungi could "...alter not only fungal decomposition of leaves but also invertebrate nutrition and production. A decrease in invertebrate production could eventually have serious fishery implications as well." The same can be said for the invertebrates. If ever there were readily identifiable dominant components of a subsystem, invertebrates and fungi are it. These are the ones to which this forest subsystem is most sensitive.
Heterotrophic organisms use fixed organic carbon (the more labile or readily metabolized forms) as their primary energy source. The carbon not incorporated may be measured as released CO2. The CO2 provides a relative and gross estimate of the rates of decomposition caused by microbial activity. This method needs to be improved and may be used in other studies.
Under certain conditions, leaf leachates can form flocculent precipitates with divalent cations that abiotically remove dissolved organic carbon from the water column where micro-fragments and leachates occur (Lush and Hynes 1973). These precipitates become colonized.
At the leaf surface, nitrogen concentrations build as protein is shifted from the plant to animals and as carbon is lost (Howarth and Fisher 1976). This concentration is part of the successional change that makes detritus more and more valuable to invertebrates (Kaushik and Hynes 1971, Fairchild et al. 1983:451). The nitrogen of the system does not change (perhaps there is some decrease due to dissolution) but it changes places - plants to microbes. Very little leaching of nutrients occurs (Fairchild et al. 1983). Of that which occurs, bacteria are the principal processors (Cummins et al. 1972, Lock and Hynes 1976, Fairchild et al. 1983). Fairchild et al. (1983:454) said, "The functional diversity of microbial and invertebrate activity probably plays a significant role in reducing the organic load of streams, thus maximizing heterotrophic production and protecting downstream aquatic resources from organic enrichment."
Large organic debris enters streams by a variety of mechanisms, some of which are interrelated and have chained reactions. Principal mechanisms of debris input are blowdown of whole trees or tops and major limbs; debris slides, avalanches, and torrents and deep-seated mass movements from adjacent hillslopes; undercutting of streambanks; and timber felling and yarding operations.
Flotation of large organic debris may be a problem in intermediate- sized streams (third- to fifth-order, drainage areas of about 400 to 6000 ha). These streams are wide enough to float large debris during extreme flood flows. Preexisting debris accumulations may be moved downstream for hundreds of meters, destroying riparian vegetation and rearranging the channel along the way.
Debris torrents are common events, particularly following clearcutting and road construction. These events transport large quantities of organic matter from the intermediate-sized streams. Although debris torrents are spectacular events of real management significance, they actually move material relatively short distances (up to several kilometers). The ultimate export of large organic debris occurs in the form of fine particles and dissolved matter resulting from breakdown of wood by the action of decomposer organisms and invertebrates including snails. Organic matter in a log in a stream high in the mountains will eventually pass through many organisms in the course of transport down river to the sea. The more transfers, the better managed is the watershed and its river.
Accumulations of organic debris may form as a result of sorting of debris in the stream during high streamflow. In large streams, there is great opportunity for debris transport and sorting to take place; consequently, the debris in intermediate and large streams tends to be concentrated. Generally, organic debris in small streams is randomly distributed. Because of this scattering of debris and the large size of individual pieces relative to channel dimensions, it is seldom possible to identify individual accumulations in first- and second-order streams.
The quantity of debris in a stream channel at any time reflects a balance between the processes controlling the debris inputs and outputs of the stream system. Factors which control the input of large debris to the stream system are age and condition of the surrounding timber stand, the stability and steepness of banks and adjacent hillslopes, and the ability of the stream to bring in new material from upstream channel areas. The export of large organic debris is determined by the ability of the stream to float debris downstream, rates of decomposition and physical breakdown of debris in channels, and the probability of more debris torrents flushing out the channel. In many instances, input and output take place in sporadic events occurring every few decades or centuries. These include major episodes of tree blowdown, extreme discharge events, debris torrents, and stream cleanup following logging. In most streams, however, a continual give and take accumulates debris slowly as it traps floated material while another accumulation along the stream may be collapsing and breaking up into small, floatable pieces after a long period of rotting. It is, therefore, important to view the status of stream debris from an historical perspective.
Several lines of evidence suggest that before recent management efforts had been made, small streams had high concentrations of debris throughout most stages of succession of the surrounding vegetation. Rotting of logs in or above streams is appreciably slower than that which occurs where they are lying on the ground. Therefore, debris may be in the stream a long time, possibly remaining in channels well into a second- growth stand developed after wildfire or early agriculture. Flushing of channels appears to be controlled more by slope stability factors (debris slide and earthflow activity within the drainage) than by cycles of debris accumulation in the channel that are terminated by periodic cleaning. These observations indicate that small streams draining moderately stable watersheds may have contained abundant large organic debris for much of the past few thousand years.
It is now evident that (1) large concentrations of debris in streams occur naturally; (2) debris may have residence times of more than a century; (3) debris increases the roughness or stair steps of the channel, causing sediment and floated organic matter to be trapped and slowing the movement of these materials through the stream system; (4) a large proportion of the stream drop is in fall over debris, thereby dissipating much of the energy of a stream at a few points along the channel rather than more uniformly along the channel of streams; and (5) the impact of large debris on channel morphology is complex, related to geology, and is probably site specific (unique). Streams under the influence of debris deny determinism. Debris causes stream channel width to be wider and more variable in forests than where there are open, grassy areas with sod-banks. Debris has a variable effect on stability of the banks and bed. Stability is enhanced and the channel is narrowed where root systems extend through the banks and channel bottom. The channel may also be destabilized and widened above debris dams and where trees are tipped over. In drainages larger than several square kilometers, stream width is more uniform than in smaller basins.
Large pieces of debris in streams tend to destabilize streams, particularly in gravel-rich streams with hillslope instability. In these settings, large organic debris may slow sediment transport and cause deepening and shallowing, both stabilizing and destabilizing the stream at different points along the channel. On large streams that can float most of the debris which enters them, the debris plays a minor role in the stream environment.
Cleanup operations themselves may be"over zealous," removing valuable components of habitat for fish and other organisms. What are the long-term consequences of eliminating large organic matter from streams? It is impossible to answer with certainty but it seems likely that many small streams will undergo down-cutting and become effectively "channelized" on bedrock or a stable boulder pavement. A stream which previously flowed over a series of steps or cascades formed by debris will assume a more uniformly steep profile and experience other changes in channel geometry. There will be a resulting decrease in diversity of stream habitat as pools are eliminated. Oxygen content as well as mineral content of the water may be reduced. Increased water velocity will also contribute to the accelerated transport of fine organic matter through the channel system, thereby decreasing the opportunity of stream organisms to process the material. Consequently, the removal of large debris from streams may reduce long-term biological productivity and increase the rate of sediment transfer from headwater streams to downstream areas.
One way to evaluate the role of debris in sediment routing is to compare the volume of sediment stored behind debris in a channel with annual sediment export from the channel. Annual sediment yield of small forests may be only about 10 percent of sediment stored in the channel systems.
The overall storage capacity serves to buffer the sedimentation impacts on downstream areas when there are pulses of sediment to channels. A sediment pulse may be from a recently-plowed field. Scattered debris in channels reduces the rate of downstream sediment movement and tends to feed sediment through the stream system in a slow trickle, except in cases of infrequent catastrophic flushing events.
Biological consequences of debris are:
In much of the world, so much area has been cleared and large logs removed (or never allowed to enter streams) that the energy of modern streams greater than first-order has been unaffected by major organic debris. Currently the only large wood now available to streams is that of young porous trees. This has now been true for several hundred years. The contrasts in the remaining wilderness streams are conspicuous.
With both moderate and excessive debris loads in streams, there is no single, simple set of rules which can be applied indiscriminately. Each site presents a different set of conditions of stream biology, channel gradient, status of stream debris, conditions of surrounding timber stand, abundance and size of bedload, and slope stability in the drainage. The great complexity of the stream environment means that each site must be inspected in the field and treated uniquely. Debris management problems call for a high degree of cooperation between specialists and administrative personnel and at least as great interest in downstream conditions as in the stream reach itself.
Progressive design and management of logging operations and/or buffer strips will help to minimize the impacts of both long- and short-term alterations of the stream environment. Other generalized guidelines are:
Greatest return on management efforts to minimize stream damage and maximize aquatic fauna will come from protecting first- and second-order relatively long, straight, torrent-prone channels.
The faunal system manager will usually be seeking to increase or stabilize a population of interest. To do so usually requires stabilizing the quantity and quality of the faunal volumes of those species. Streams are such important wet places so dominant in supplying life needs to so many related life groups that managerial efforts to stabilize them are essential. Leaving them to someone else is to surrender control of the faunal resource. How much greater good would result from a cooperative effort at a task none of us can achieve alone?!
Models of stream runoff are needed. Suspended sediments, bottom sediments, and organic debris are related to runoff. The stream bottom and the debris network in streams is the place of attachment and feeding for a system ranging in complexity from diverse redox cycles and enzymatic action of cooperative aquatic microorganism on stream particles through predator-prey relations and density of organisms per square meter of within-stream sediment surface and riparian zone.
Martin et al. (1985) found that mayflies and true flies increased in streams within clearcuts apparently due to temperature increases. Clearcutting, for example, does influence streamwater chemistry and biology throughout New England (and presumably elsewhere). Depending on the site, it may increase stream nutrients (nitrate-nitrogen, calcium, and potassium). Depending on the organism present or subsequently present, the effects may be"drastic" or not ... depending on objectives (not the significance level selected for a statistical test). What fish or complex insect fauna or floral shifts will be made have to be the questions for people cutting trees. Perhaps we do not know enough to know what the real effects are. Not knowing demands caution. Even children are reluctant to push keys on a personal computer until they learn that it will not hurt them or the machine.
The Surface-Subsurface Layer
The ground layer, a problem in definition, is about 50-60 tons of organic matter per hectare. It is populated by fungi, the mature fruiting bodies of which are called sporocarps. Some produce fruit aboveground (mushrooms) and others, sometimes called "truffles," fruit below the ground. Forest rodents prefer truffles which emit a strong odor when mature (McIntire and Carey 1989). Deer and other wildlife have strong preference for mushrooms (Maser and Maser 1988). The endomycorrhizal fungi spread slowly, mainly by water, soil movement, and by mammals and insects. Trappe and Maser (1976) found spores were viable after they had passed through the digestive tracts of rodents. Ponder (1980) demonstrated that rabbit feces contained viable spores. It is well known that the "roots" of fungi, the mycorrhizae, form a system with tree roots and significantly improve tree growth by assisting in nutrient uptake from soil particles. The vesicular-arbuscular mycorrhizae are significant in the physiology and ecology of vascular plants and may have facilitated the origin of the vascular land flora. Only in 1987 were arbuscles found in the fossil record of the Triassic (Stubblefield et al. 1987). Newly planted tree stock or planted stock is often inoculated to assure their development in soils unfavorable to the fungi. (Such areas include forests, marshes, and surface-mine reclamation areas (Ponder 1980).)
By this one mammal-driven aspect of the forest, the mycorrhizae increase site index. Thus tree growth may be increased by a factor, over the life of a tree, of approximately 5 to 10 percent or more. (See Hatchell et al. 1985.) A forest with a well-developed, deep mycorrhizal layer is likely only to have developed rapidly by mammal of a community or is one that has been developed by rodents and has experienced persistent light and moisture relations (unlike the large unshaded clear cut). Forests with such layers are more productive than others in the same soil. Deep intensive burns can reduce the mycorrhizal layer but the spores are abundant and "tough." Cork and Kenagy (1989) reported that even through hypogeous fungi contain high concentrations of nitrogenous compounds, vitamins and minerals, and are abundant at certain seasons, the digestible energy in them is low and the nitrogen is largely in the indigestible spores. The situation seems one of an optimum "strategy" by the plants to produce abundantly and to have an attractive odor that assures consumption of the spores and rapid, deep-soil dispersal by fauna. Wind dispersal is evident, but movement deep into the soil is poor and thus strongly related to animal activity. For those who only want to know "the bottom line, " the worth of the well-developed forest mammal (rodent) fauna is probably at least 5% extra tree growth on a site.
Rodents eat forest seeds. How many seeds are needed to produce a well-stocked final stand of age 10? Should the measure of rodent effect be one of stocking costs or foregone long term growth? The answers will usually be site specific and measured by increased site quality or net present value of the tree crop expected to be harvested plus extant land values, not by an estimate of "seeds-not-consumed and germinated and surviving, unthinned."
The surface of the forest floor and its use by fauna is related to the vegetative cover there, the woody material or litter, obstructions and stem density. The forest floor is alive with birds and mammals feeding there on fauna within it. Within the subsurface layer rodents aerate the soil, increase permeability and percolation, and reduce compaction. They build channels used by roots and in which debris is carried. There are reduced nutrient losses related to their activities. Insects and other forms are prey for fish, birds, mammals, and lesser life forms. Most serve as"buffer species" reducing predatory pressures on game animals. They consume or breakdown large debris including antlers and skeletons, provide a protein pool (nitrogen) for certain plants, serve as a nitrogen source after death for a point of reseeding (from gut content) and invasion phenomena. They disperse, scarify, and deep-bury seeds.
Just as Microtus is the prey base of grassland systems, Peromyscus is the rodent-prey-base of forest systems. The shrew, Blarina, is also a major component of the layer just as are salamanders, snails, crustaceans and, as always, insects. It is possible to work out strong relations between rodent or shrew densities and forests. In one Virginia cove hardwood study, Peromyscus density per hectare (P) was related as:
P = 30.96 + 0.962 T - 0.079 H + 0.002 V + 3.076 C
where T is an index to tree heterogeneity, H the height of dominant shrubs, V the variation in bare soil and C the percent of tree cover. The R2 was 0.9! (Bliss 1979). The equation is locale-specific but shows a model by which a manager can decide actions to take, for example by influencing T, H, or C by thinning or selection harvests. The management of the forest floor is an unemphasized but critical part of the task of the wild fauna system specialist (Harvey et al. 1987).
Wildlife clearings, waterholes, and bird houses are conspicuous faunal spaces created by people. Much more influential and more massive is the litter layer of the forest, the mantle. Litter (recently fallen) and forest residue is all dead and down woody materials on or near the forest floor produced by natural processes as well as by logging or other intensive forest uses. It should be called organic detritus (Odum and de la Cruz 1963) to include litter (comprised of bark and bark particles, other plant parts (e.g., lichen, grasses), stems, twigs, branches, duff (partially decomposed materials), and even large dead trees and animals. As Odum and de la Cruz (1963) pointed out, the layer is itself not dead but the name of a community of micro-organisms associated with a non-living substrate that also includes soil particles. They viewed the layer as a group of dependent heterotrophic systems functioning within a larger autotrophic ecosystem. Natural processes such as blowdowns; self pruning; disease; needle, bark, and leaf fall; ice storms; winds; and fires all produce detritus. Detritus is the mixture; organic detritus the once-living part; litter the name of the layer (also a word meaning recently-fallen material).
"Residue" is translated by forest fire prevention specialists as"natural fuels" and its accumulation is said to result from fire prevention and exclusion or suppression. The weight ranges from 5 to 35 tons per acre (12-86 tons/ha) in some stand types to 80 tons per acre (197 tons/ha) in the Douglas fir area.
A thick, vigorous litter layer "plowed" by fauna creates a zone for water input and storage of major importance to tree growth. Without the layer with its "antifreeze" organic solution, impenetrable frozen layers can form, preventing water percolation to the root zone or to groundwater and accelerating surface flows and sediments harmful to stream fauna.
Odum and de la Cruz (1963) noted that even though there are abundant herbivores in ecosystems, the percent of the living biomass they consume or process is very low. Insects and disease are conspicuous; so is the living tree and stand. The growth equivalent to the tree is in the thin, inconspicuous, "underfoot" layer, a volume with a continuum of particle sizes, nitrogen levels, C/N ratios, and dissolved organic acids.
People differ in the pressure that they apply in taking samples of the litter layer, in tool use, and in decisions about roots to include or exclude in sampling. Minimizing the observers is one way to improve samples, estimates, and comparisons of layers. Rules of sampling may be used (e.g., limited number of scrapes, only to depth at which a probe stops). Portable vacuum devices may help standardize the amounts collected and weighed.
The depth of the layer is a function of the balance between oxidation and emigration rates and primary production rates. The undisturbed old-growth forests typically have a production (P) to respiration (R) rate ratio of nearly 1.0. The manager can change respiration or removal rates by restricting recreational and animal use (mechanical breakage), by protecting the understory from wind, by preventing grazing, and by protecting areas from fire. Increasing the population of firewood gatherers (Sedell et al. 1988:69) reduces the layer. In severely changed areas, surface runoff and erosion can reduce litter and residue.
Whole-tree-chipping has greatly reduced litter on some areas, influencing nutrients available in the surface rooting layer, water percolation and storage, and faunal habitat. This layer influences faunal abundance (typically of Peromyscus and Blarina in the East) mycorrhizal dispersal and its abundance, and nutrient availability to the tree and other layers. Some fungi, dependent on a deep litter layer, are nitrogen fixers (Jurgensen et al. 1989). Decomposition rates, high in spring, can cause high nitrogen uptake or retention and make it unavailable to trees. Soil fauna populations in abundance, feeding on bacteria and fungi, can suppress this phenomenon and make nitrogen available for tree and understory growth.
Once called "controlled fires," a technique for forest management, they are now "prescribed" because it became clear how difficult control was. Fires are necessary for or at least one of a few means for creating and developing some forests. They kill some animals, create foraging areas for others. They produce short-term nutrient spurts in forage, long-term losses of snags, increases in stream temperatures and siltation, and they kill some trees, creating new snags. They are so diverse in their effects; so differentially prescribed, contained, and suppressed; and so dependent upon objectives, that there is little that can be said about them in less than a book. That little which can be said may be: (1) prescribed fires can be effective in faunal system management; (2) great care is needed in its use including careful studies, adequate suppression crews and equipment, and attention to soil moisture and fuels that minimize harmful influence on the litter layer; (3) time of burning relating to growth conditions and seed sources is the key decision; and (4) fire is little more than apparent oxidation of the same effects as those from fire are gained over time by other processes - many of them faunal. The oxidation of fires is coupled with high temperature (desirable or not in each situation), high loss of nitrogen (usually undesirable), change in nutrients available to plants (plus or minus), and loss of forest structure (of great importance to many animals). Analyses of net effects are essential for the decision to use fire.
Understory
Once considered unmerchantable, understory trees (less than 5 inches (13 cm) dbh) and shrubs may now be harvested for fuel, fiber, mulch, etc. New chipping equipment, new products developed, competition for wood, and demands for energy wood and fiber make harvesting the understory possible. Economics, policy, and available energy may decide whether such harvesting is actually done. One realm of policy will be whether the consequences of such use to the faunal system are desired or not. Removal will benefit some species, be disastrous to others. Whether removals will be made will be one branch in the decision tree; how, when, what pattern, and how frequently will be the other difficult nodes.
The shrub or understory layer is not well defined and estimates of biomass in this part of the forest vary widely. Phillips and Saucier (1982) used 4.9 inch to 1 inch dbh as a stem size criterion (since 5.0 is the so-called merchantability limit). Thus, all small trees as well as shrubs were included. Others have included herbs (forbs). Equations have been developed for green weight per unit area. Phillips and Saucier (1982) observed that understory biomass may range between 5 to 20 green tons per acre and about 25 percent of the total stand biomass. Because some shrubs are very shade tolerant, understory biomass does not relate well to characteristics of the overstory layer. These weights are of great interest because they are a potential source of fiber for pulp and fuel. Certain faunal species depend upon the understory for reducing wind convection energy losses, insect prey, nesting and cover, and watershed surface stability. Wood characteristics may differ slightly between regions thereby justifying using different equations.
Foliar cover is the total proportion of ground surface (within one m2) shaded by all plant parts when plants are standing naturally. The use of a human fist provides a sample area of about 0.01 m2. This or a measured open-hand area can be used to improve ocular estimates of cover within plots. These have been shown to be satisfactory at the 0.10 level of confidence when compared to a point frame analysis (Popham and Baker 1987).
There is likely to be a strong logarithmic relations of basal area of stems and the product of the crown width and its length to annual foliage yield of shrubs.
Wendel and Lamson (1987) demonstrated that tree diameter growth could be increased by using herbicides on all stems around selected hardwood crop trees. These trees may be selected for wood production or for a combined production of hard mast or nest sites. Thinning around crop trees has the usual secondary effect of allowing grasses and forbs to grow that may be of use to other managed species. Whether long-term, monetary benefits in wood production will exceed costs is not yet known but, if the relationship teeters, then certainly additional wildlife benefits (if among the objectives) can be listed to allow a positive benefit-to-cost ratio.
Crawford (1971) studied the effects of intermediate cutting of hardwoods on understory vegetation. He found that tree sprouts overpowered desirable understory forage plants except on the better sites (site index greater than 70). On poorer sites, sprout growth would have to be controlled to obtain the better food species.
Patton and McGinnes (1964), as others, have studied the effects of thinning trees, reducing stem density, and "opening up the canopy" on wildlife forage. The pattern of change with percentage of tree removal or thinning is exponential (as also found by Crawford 1971). Crouch (1986) has reported how thinning can increase the understory vegetation and then animal foraging in the thinned stands. The needs remain for analyses of how much more foraging is needed or useful, then for site-specific thinning rules expressing desired air-dried forage as a function of basal area and stems per hectare.
Nixon et al. (1983) described how small hickory (Carya) trees (7.6-20 cm dbh) can be released in clear cut areas and then managed to produce hard mast important to many species. The prescription: seek to retain 30-35 nut-producing hickories per hectare at stand age 30 and retain them to rotation (or beyond) age. Manage the stand for replacement trees at harvest (perhaps a clearcut). Release small trees. Favor trees in clearings more than 50 meters from the uncut forest edge.
In addition to the poles, there is typically included all plants in the understory. This is a dynamic number. Stransky et al. (1986) found 359 kg/ha in a loblolly-hardwood area that reached 3,462 kg/ha net community production in about 5 years, then returned to 383 kg/ha 10 years after initial treatments. Woody plants drop after site preparation, but regrow to pre-treatment levels in 10 years (Texas).
Stransky et al. (1986) observed that 68 percent of the 105 herbaceous plants in cleared forest areas only grow there, not within the forest. Herbaceous plant productivity decreased with all site treatments (burning, chopping, etc.), but not after KG blade treatment. Smith (1986) and Smith and Brand (1983) presented equations for understory plants in the northern Lake State forests. The total green weight in pounds per acre ranged in most stand types from 3,000 to 8,000 pounds, but in tall-shrubs of the elm-ash-maple type the weight reached 21,640 pounds, the maximum observed. Phillips and Saucier (1982) observed great variability in the understory, also that many species were shade tolerant, and concluded that detailed measurements within plots (e.g., 50/acre) were needed. They could not find a good easy measure (e.g., overstory canopy or basal area) that allowed accurate estimates of biomass. The weight obtained by Phillips and Saucier (1982) was 19.1 tons per acre. They summarized other studies showing understory biomass ranges from 5 to 20 green tons per acre and is about 25 percent of the total stand biomass.
Ostrom (1983) reported low and tall shrub biomass in Michigan in green tons per acre as:
| Tamarack Black Spruce Balsam Fir Elm-ash-soft maple Northern White Cedar |
2.3 1.6 1.4 1.1 0.9 |
Kie (1985) did, however, develop good equations for two western shrubs of the form:
Total Weight = b0 + b1 V + b2 V2 + b3 C
Where V is volume based on a shrub treated as a cylinder and C is crown closure from a wide-angle-lens-photo taken 1.5 m from the ground. Mitchell et al. (1987) found good relations for grasses, forbs, and shrubs in the understory of ponderosa pine. Biomass was expressed as kg/ha of air dried material. The equations were:
Grasses = 8.17 C (R2 = 0.80)
Forbs = 13.66 C (R2 = 0.62)
Shrubs = 21.03 C (R2 = 0.81)
where C is estimated percent overstory cover.
Phillips (1981) presented excellent estimators for understory weights based on diameter and tree height of trees in the Piedmont and mountains of the Southeastern U.S.
Ohmann et al. (1981) related how understory biomass was needed for estimating food for hares and the browse available to other wildlife. Food preference, nutritional quality, and digestibility along with biomass can provide fundamental knowledge for the system manager. They estimated the percent of ground plots covered by plants, then weighted them. A log-log plot of cover and biomass was linear, thus a Y = AXb relationship, where X is cover. Ohmann et al. (1976) presented equations for estimating above-ground biomass of 5 species of shrubs often browsed by deer and moose. With care, it now appears that basal area estimates (prism) and stem density can yield "cover" and this can lead to useful estimates of understory conditions or potentials for many animals.
Brand (1985) developed environmental indices for trees and shrubs. These quantify how a plant integrates the complex of major environmental factors, namely moisture, nutrients, heat, and light. Since these factors influence how forests grow and how foresters manage stands, knowledge of them is important. One way is to comment on each. An alternative is to report shrubs that express them. Actually measuring them is often difficult or expensive. Balsam fir, Abies balsamea, for example, has environmental indices for moisture of 4; nutrients, 2; heat, 1; and light, 2. Values range from 1 to 5 (with 1 meaning dry, poor, cool, and dark) for each of the above categories respectively. As an example, two aspen stands may be about to be treated for grouse management. On the basis of species in each stand, one has moisture-nutrient indices of 3.8/2.5 while the other has 1.4/2.6. The higher moisture of the first stand may suggest a white spruce intermix, red pine for the second. See CAP5024.
CANOPY (Moeur 1985) is a computer program developed for modeling understory vegetation (Northern Rocky Mountain conditions). It extends the model PROGNOSIS by providing a description of the amount of cover and foliage in the tree canopy by height class, the height and cover of shrubs, forbs, and grasses in the understory, and a summary of overstory and understory cover and biomass for the stand. Applications of the model are said to be:
Deer live in a layer of the forest from 0 to 75 cm. Under extreme food shortages they will stand on their hind legs to feed. Other times they dig out insect masses, occasionally eat a dead fish. They will walk on frozen snow and feed high in the forest. These excursions outside of the normal layer are interesting, worthy of note, equivalent in public relations value to a"freak show," and in a very sophisticated computer model can be imagined as included in some final check on animals that an area will support. When the population is about to starve (in a model), some proportion may be allowed to move out of the layer to see if there is additional available forage for them at that time in that year. Interesting! An explanation for some of the variance observed in deer populations! But hardly the bread-and-butter data needed by the average manager. With a few exceptions, managers are far from having and using sophisticated models. They are available (e.g., DeerCamp by A. Moen, Cornell Univ.) but not widely used. They need to be brought into every day use.
Other animals "live" in layers. This is a frequency of occurrence, a probability-of-being-observed statement. A life group can be found in one layer a high proportion of the time within a season.
This is the end of Chapter 7, Part 1. You may proceed to Chapter 7, Part 2.
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