Forest Faunal Systems

Chapter 16

Cumulative Effects

The way the land is used effects faunal spaces and thus animals and thus benefits from them. A dam covers breeding grounds. The effect is on the fauna of the area. It is also on adjacent areas where the stock that once was produced is no longer present as adults (the density is less). The effect is on the people who no longer have access to use the resources, either under the water or in the blocked-off inaccessible areas. Effects may be to habitat where the microclimate is changed, or to animals no longer hunted and that now over-utilize food supplies. Developments have effects that are both on-site and off-site. These can often be described as within a zone of influence, (discussed in Chapter 7), for animals and for users of the developments. They may be positive or negative, depending on objectives. Effects are long and short term. They may be annual and unnoticeable by the end of a year, or they may accumulate, like effects of litter falling over many years on the condition of forest soils. They may be singular and small (as from the influence of a small house in the forest), or they may be two or three, and then the singular development with several parts may be realized to be having a great effect when a threshold is passed. The entire residential community is causing a change. Once an area known as "the grove," becomes known as "forest lawns" then change has occurred. When did the change occur? When did the changes change from "tolerable" to "impacts?" "Cumulative effects" is a phrase having prior use with thresholds, suggesting a buildup or that additions occur until some point is reached. It is a point beyond which viable populations cannot be maintained. (Not to mention effects on benefits ... or creating a situation in which there are continuing maintenance costs!)

Whenever an area is used or "developed" where annual production is lost (k_t), that total loss over all time is:

K = k_t

and since forever may be a very large number, few people will allow such a calculation of K to be used. It does seem reasonable, however, to estimate losses of total potential production and associated use over a planning period, say to 50 to 100 years.

"Cumulative effects" has negative connotations just as does "impacts," and besides being pejorative, its use may constrain analyses and creative action. Formal system managers will move in the right direction by thinking and talking about "net long-term effects" of actions taken or alternatives selected. It is as important to think of positive cumulative effects as well as negative ones. Wildlife openings or sod clearings along a forest trail may be a useful example of the dichotomy. What is the effect of 2 such openings in the forest? Of the next 10? A large woodland cleared at the edge? The forested area changes from 100 acres to 60, then to 50. At what acreage do certain bird species disappear? When does the drying effect of the sun and wind in the edge zone that increases as a proportion of the remaining woodlot eliminate suitable conditions for salamanders? It is also important to confine thoughts about effects to topics identified in objectives. Otherwise, there is no reasonable end to the effort to describe all possible long-term consequences of any decided action.

Personally, there is a big difference in the dollars that I have at the beginning of the month and those at the end. A dollar is not a dollar. The fewer, the more prized. The same is true for societies and their wilderness, for white water, and prized wildlife species. As such priceless things are lost, they become more valuable. The monetary comparison is useful, but the biological analogy is even more telling. A person might have a small part of their liver removed and suffer no major harmful effect. More, and the assurances of survival are less confident. Removal of most of it will produce death. The death analog is extinction for animals. As more and more habitat that is especially needed by a species is lost, the closer that species (at least the genetically important population) comes to extinction. (See CAP08 and CAP12.)

The loss of special habitats (not just any or all habitat), those needed for life function (such as denning by species X), may be cumulative. Very little wildland is being gained since most change is caused by people, and the results are rarely pro-faunal (at least terrestrial). A forest pond conspicuously removes space potentials for terrestrial life groups, gains them for wet-place fauna. Nevertheless, net change must be considered. The analyses of cumulative effects are limited, for they are difficult and can be even more harsh on would-be developers than the now-conventional, relatively site-specific, impact analyses.

Cumulative impact is the impact on the environment which results from the incremental impact of the action when added to other past, present, and reasonably foreseeable future actions regardless of what agency (Federal or non-Federal) or person undertakes such other actions. Cumulative impacts can result from individually minor but collectively significant actions taking place over a period of time. (CEQ regulation 29 November 1978; effective 30 July 1979; 40 CFR parts 1508.7 and 1508.8)

This description and pseudo-definition begs for clarification. The effects being addressed include:

Total - e.g., when three similar developments such as power plants will be made at about the same time at different places within a valley.

Sequential - e.g., the effects of a total highway length, not just each project segment. Another example is a system of dams along a river.

Fig. 16.1. Area-wide negative net cumulative effects or impacts canbbe conceived as a declining environment.

Incremental - e.g., progressive loss of important faunal spaces over time. This may include items (like tree snag or waterholes), areas, or volumes. Summer homes along a lake are a conspicuous example. Influences may be expressed in counts or as a scalar. Some of the difficulty in past analyses of environmental problems has been in scale. A very small apparent "clearcut" may actually be a well-executed group-selection harvest. The great expanse of some clearcuts offends some people, not the cut itself. There may be and probably are non-linear phenomenon at work. The next small increment may appear to or actually result in exponential change in the life-quality conditions of people or the resources for animals. In the non-exclusive mix of categories available to the developer or analyst working on developments (Total or Incremental) is the devious ploy of cutting 5 small, legal, 40-acre clearcuts in adjacent watersheds in a few years, the result of which is a 200-acre clearcut. A related example is the effect of hiring a "temporary" employee for 90 days, then extending that employment for 3 more periods vs. hiring a "permanent" person for a year. Foresters who return years later to their old working area are familiar with the feeling of disgust that wells up upon seeing what one or two subsequent foresters have done in multiple harvests made over an area that they had once so carefully designed and conservatively marked for quality timber and wildlife harvests for a 100-years.

Wetland drainage is another example of incremental effects. "A little loss won't hurt!" is the logic. Decreasing size of forest stands can be viewed as a cumulative effect phenomenon. Alig (1985) showed how such changes can be modeled. Knight (1978) discussed the economics of scale of forest owners. Small forest tracts may be less efficient than large ones. These tracts are also less species rich. Harris et al. (1979) reported a species area curve for birds of S = 5.12 A0.35. As size A (in acres; 0 to 25) decreases, the bird richness decreases. (See also Forman and Godron (1986) and others on the size of forest "islands.") In the Piedmont of South Carolina, 30 percent of the timberland is broken up into stands smaller than 10 acres (Knight 1978). Of course, all size stands are needed for large regional avifaunal richness (Whitcomb et al. 1976).

Additive - e.g., particulate pollution from a factory; solid waste along a forest road. Like "incremental," with its connotation of a particular time, the negative influences occur as a result of additions or subtractions of substances, not areas. Removing water from a stream shows one of the most conspicuous cumulative effects. Under certain water rights laws, people can take water without regard to downstream effects. Eventually, no water flows. Even where some flows, the fish, riparian vegetation, peak flows, and many ecological factors are changed. The instream flow analysis and regulation methodologies of the U.S. Fish and Wildlife Service address this important area for development. There is a need for a minimum flow or a flow regime below which withdrawals are not permitted. How to determine this level and how to achieve it after it is determined are both questions in a policy and law matrix. Lamb (1989) discussed the long-running controversy and warned about adopting high-technology approaches laced with assumptions and approximations. He, as most people involved in faunal management, felt perplexed by the conflicting requirements of very accurate results within an extremely complex system and those of quick answers, cheaply.

Synergistic - Combined effects that are greater than additive ones, e.g., the loss of much food by large-tree harvest and simultaneous loss of energy-conserving den sites results in significant losses in an energetic system. Subsequent loss of food-plant-seed-dispersers living in dens in the area has long-term effects on the type and structure of the future forest. Progressive vandalism of forest signs has synergistic effects throughout a forest in litter, trespass, public inputs, fire problems, watershed controls, etc.

I am hesitant to add to this already-difficult analysis "induced effects" to these effects of land use change that are now called secondary or "externalities." I definitely do not include the influence of every development on every forest resource since this is equivalent to the questions asked in every multiple use decision. This seems to be the approach of Bain et al. (1986) but it may shed light on multiple-use decision making. They defined cumulative impact as "...the total effect of multiple land uses and developments, including their interrelationships, on the environment."

Horak and Vlachos (1982:9)) presented a general view of how conditions for a species, life group, or aggregate environmental index might appear. Objectives are vague; the upper line, "excellent," represents present conditions or potentially those desired (for what else is the role of management?). The system might come to fluctuate about "fair" under management (how little confidence in the manager!), obviously with costs. The efforts of the faunal systems manager can be to replace, mitigate, or produce on remaining lands the benefits implied by the "fair" line. "Failure" presumably occurs when a population is below a minimum viable size, structure, and function.

A reasonable cumulative effects analysis might start with an appraisal of the total available habitat (given some statement of system context like "within state A," or "West of the Mississippi"). It is T, and, for example, is 100,000 hectares. (See Fig. 16.2 below.) C is the cumulative effect index, an expression of the change that a project will or has caused in the residual habitat. Given that a project will influence 900 hectares on-site, reduce 100% of a population on that area by 100% and cause reduction in populations by 50% on 37,000 additional hectares, then there are 16,500 hectares equivalent of adjacent influence. The total effect is on the equivalent of 17,400 hectares. Since 70,000 hectares have been influenced similarly due to previous development and called K, more formally:

K = k_t or K + k_p

Where K is the total lost from all projects (k_t) over the period, say from t=1 or the first year of human settlement to the present, p. Then the residual is

R = T - K

The effect of a proposed project on habitat (or population or users or their total) is k_p+1. This is the effect on habitat or it could be expressed as being on the total population or on the potential amount of resource use such as sightings, days of success, or total observation hours...or their aggregate. I prefer analyses based on the estimated effect on potential user benefits (not the space for a population).

The results can be seen in Fig. 16.2.

Fig. 16.2. Developments and related habitat losses accumulate. Each step up is the completion of a project (e.g., a dam) and the net loss of a portion of a species total available suitable habitat. At a point, a decision needs to be reached about whether the influence of k is tolerable. See q described in the test.

The cumulative effect index is

C = k_p+1 / R

where T is 100,000; K is 70,000; and k_p+1 is 17,400; then

C = 17,400/(100,000 - 70,000)

C = 0.58

The higher the index, the greater is the estimated effect. The expression for aggregate effects is

C = a k D_p+1 + b kE_p+1 + c kF_p+1 / (aR_D + bR_E + cR_F)

where a, b, and c are expressions of relative importance or the value of each component (D, E, and F) and are subjective. These are "weights" discussed in Chapter 4.

When an upper-limit policy or law exists (as it should), then T is replaced with q, the limit decided beyond which no further loss is viewed as tolerable or viewed as too risky. Then, if C ever exceeds 100, a system so devised would trigger a halt. Figure 16.2 suggests that a policy or law (symbolized by the q line) could be established that would prevent developments that would cause the aggregate line to cross q. It expresses "enough is enough." Development is allowed but it is monitored and society may decide at what point it will tolerate no further losses or negative influence.

There is a more complicated side to the "cumulative effects" issue. It is related to the statistical concept of degrees of freedom. This is complicated too but at a primitive level it can be handled by the example of people entering a committee room with 5 seats. The first person to arrive has complete freedom to sit anywhere. My confidence increases in predicting where the next person to enter will sit and after the fourth person is seated, I know where number 5 will sit. Thus, my knowledge or confidence is related to the seats (n) minus 1, the familiar n-1 expression.

"First in time, first in right," the expression of water resource law, relates well to cumulative impacts. Project A₂, one second later but of lesser magnitude and better design than project A₁, may be declined if its additive effect with project A₁ will surpass a threshold. How easily we see the local situation (even if it is frustrating), but fail to see that the doctrine of "first in time" pits us against our grandchildren. We assume the rights in time and unless we are very skillful managers, we may have little for their inheritance. Casting ahead, they would certainly not want us to waste or deprive ourselves unduly for them. Playing the role of the reasonable adult grandchild may reduce the emotions of current debates with some parties seeking to maximize opportunities and resources for future populations.

In forest systems, what happens next, ever, is often largely pre-determined by past actions. There are not a lot of degrees of freedom. A faunal system manager may want woodpeckers but if the forest is young, he or she will just have to wait ... sure that there will not be any soon. It may be desirable to have type A contiguous to type Z but this may be impossible or totally infeasible for several reasons.

In forestry situations, cumulative effects of harvests, fires, regeneration, etc., can be estimated, but they need to be judged against a standard, some expressed best possible condition, a rough equivalent to R, above. Call it R*. The effect over some stated period, say the next 50 years, will be in the difference between "the perfect forest" and the actual forest. The "perfect forest" is one producing the desired set of weighted wildlife species and densities, one regulated in harvests by type, site index, density, age, and contiguity or proximity over at least 50 years, e.g., as developed by procedures described in Chapter 7.2. The actual forest is the present forest and the one that has just been produced or is proposed to result from the next action (e.g., to cut 30 hectares of stand D). The present forest (in reality, any habitat) is an expression of cumulative effects, effects that are natural as well as the differences caused by people. The cumulative-effects literature could readily be merged with that of succession with possible strengthening of both. Each year the status of an ecological system is a function of all that has gone on in past years. A succession curve is a cumulative effect curve.

The analyses of cumulative effects can be done using a series of couplets (as in a dichotomous taxonomic key). For example, when a yes-no pattern is set, one such as "sprayed-not sprayed" or "hot burn - not a hot burn," then all reasonable pairs (n) produce 2ⁿ possible outcomes. Where n = 30, then the large number of possible states of the forest, 1,073,742,000, can be impressive. This diversity of options has caused some people to poo-poo "succession" because a nearly singular predictable outcome seems unlikely. The frequent "no" among many "yes-no" couplets (the constraints) tends to produce forests that look alike, forests that, though having taken many different pathways at the n-1 nodes in the decision tree, arrive at the same end state. They display equifinality.

The cumulative effects of forest harvesting can produce the perfect forest. A fire or insect outbreak may cause deviation. It may take years to get the forest back to the desired state again, but it can be done. Every action could realistically produce very positive results because its effect on C would be through K as well as k_t+1.

You have to know what the effects of A are before you can know what A+B will be. There must be a data base and each proposed change must be judged based on the current conditions. That judgment will eventually include a powerful predictive model. Education resulting in a massive change in attitudes toward models and the concept of feedforward is needed. We cannot continue to act as if the natural world of the future was some totally unknown void. Horak and Vlachos (1982) commented on the high investment required in such data bases but they, as others, were quick to point out the high cost of not having one. Some centralized or unifying system will be needed because of the great resource agency differences - in objectives, responsibilities, and modeling capability.

Missing from most impact analysis work is the force of law that decrees when it appears that significant "impacts" will occur, then the proposed project will not be done. Impact analyses are just that ... analyses. Only a few things can, by law, stop a project (such as presence of an endangered species, and often not even that).

When actions are authorized, then in some situations "mitigation" of the losses can be authorized. This is a cloudy area in which somehow land or resources lost in one region can be mitigated by land acquisition or purchases in another. "...In like kind" is a key phrase often ignored. How can losses of 500 acres of superior wild turkey brood range be replaced by purchased wetlands? The courts have authorized such action, presumably under the notion that any area is equal to another, that all wildlife are of equal value. I suggest an alternative of commitment of funds to develop and manage over the long-run (now omitted in most mitigation action) forest faunal benefits on areas adjacent to or within a project. For example, when large dams are constructed, areas to be inundated are acquired as well as adjacent lands. These usually are lands not under intensive faunal management. If faunal production on 1000 acres around a reservoir can be increased by 5 times with management, and if this can be done at less cost than new land acquisition, then is not management for extra benefits (e.g., 4000) a better alternative? If one agency develops a project, then allows (almost requires) another agency to manage the land, then the appropriate accounting is not occurring. The needs for "mitigation" are for dedicated trust funds for land management for fauna and for user fees that go to management on the developed areas.

In the future, the threshold concept described herein or some related concept must be built into law that prevents society from hurting itself. Just as disease quarantine is a restriction on personal freedom, it is made possible, under the law, for the good of everyone. There are complex systems out there; everyone cannot understand all ecosystems and make personal judgments in the best interest of themselves, much less most people over the long run. In addition to site analyses, there need to be data bases that assess each new situation, and then, under law, decisions need to be made to progress ... or stop. The decision on big projects can no longer be left to the developer - public or private. Their context is too small; their objectives likely at odds with the public; their knowledge of and modeling ability limited; their planning horizon too limited; their accountability missing.

References

This Web site is maintained by R. H. Giles, Jr.
Last revision January 17, 2000.