A unit of Lasting Forests evolving since March 30, 1999
A Total Forest Management Plan and Wildland Management Decision Support System
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Pond and Lake Biodiversity: Sample for Owner's Manual

In the same way that "preserve" has several meanings to people, so does "biodiversity." To some people it means to preserve species and communities; to let none pass away. If there are 200 species in an area and one becomes extinct, then, logically, 199 is less diverse than 200. This concept of biodiversity is also known as species richness and it implies retaining those species that we have and even reintroducing species that may have once been present. It rarely includes a positive attitude toward introducing exotics.

Biodiversity, to some people, implies having many species (ecologists use the word "richness" for many species, thus some of the confusion) but also many animals of each species. This is the emphasis on "abundance." Other people combine richness and abundance in indices of diversity. There are about 20 such indices. Many indices have an evenness standard, i.e., a maximum "score" when there is equal abundance of animals or plants in each species. To "maximize diversity", according to many of these indices, is to increase to or achieve equal numbers of animals or plants in each species.

Other people imply by discussing biodiversity, that there is a need to have an actual or desired condition of mixing genetic characteristics such as occurs when large populations experience abundant exchange (by migration, etc.) of genetic material.

Other people seek many types of animals and plants in very different areas or environments as representing diversity. Areas are selected (for example for a public park) that contain great differences in soil, elevation, and rainfall. These tend to assure presence of different species.

Other people worry about taxonomy. Some people group animals and plants easily; others are "splitters", naming things with only slight differences as truly unique and worthy of a separate name. A splitter can easily increase richness. Size, weight, age, color, and reproductive contributions to a population are also categories used by some people to discuss the diversity within and among biological populations.

All of these meanings are presented here to alert the reader to the difficulty of understanding what is meant by biodiversity, to suggest ways to defend against those who claim biodiversity is not being addressed in management, and to show recommended procedures for fulfilling the good intentions of advocates. Biodiversity is now required in more than 20 laws and regulations, yet a clear definition is not available. Stabilizing, sustaining, increasing, or maximizing are undecided modifiers of the term. Time, implicit in the word sustainability, is rarely discussed. Should conditions stay the same? Improve over time? By one concept, change, either increasing or decreasing over time is "diversifying."

Useful strategies for the forest and surrounding area are:

• Concentrate action on parts (a) richest in species (or "taxa", and taxonomic categories) well-named distinctive units); and (b) on those facing the greatest threat, and
• Concentrate action on parts (a) least disturbed (the natural areas and wildernesses); and (b) presenting the greatest opportunity for long-term preservation and management to retain a natural or undisturbed state.

Objectives (of Type 6) for biodiversity include:

1. Include the rights and interests of people at the local and regional levels and build from their expressions.
2. Support laws and policies that expedite and make efficient superior land management.
3. Strengthen local managerial knowledge and abilities.
4. Manage actively unique areas, especially those characterized as "old growth."
5. Support and try innovative tactics.
6. Increase sustained financial net benefits from a mix of area resources.
7. Employ innovative funding mechanisms (e.g., endowments).

Primary objectives for stabilizing or increasing biodiversity include:

1. To retain an historical base of life and culture
2. To retain medical and food options
3. To continue to gain benefits from ecosystems now functioning with these species
4. To retain (unspecified) future options
5. To reduce the guilt of species loss in recent times
6. To retain a potential food source
7. To provide a warning system for failures in parts of the ecosystem
8. To retain bioengineering options
9. To avoid risks (e.g., pest outbreaks when a predator is lost)
10. To provide conventional biological resources (fiber, fish,, forage, firewood, fruits), tourists opportunities, and watershed protection.

Success (or failure) of the pond or stream system in biodiversity is to be judged by the index D. A maximum value of 100 may be achieved. A lesser score is not bad", simply a reflection of known conditions. With study and work, the score can usually be increased. It will fluctuate with fires, floods, timber harvests, acquisitions, and sales. A score of at least 35 should be sought, then resources and time allocated elsewhere until other opportunities arise for increasing D. Detailed, long-term studies of plants and animals are needed to get appropriate estimates of species and abundance to get biodiversity indices (about 20). The Fishery staff will develop such lists under contract. The lists need to be developed for several years and for at least two seasons to include breeding populations, wintering populations, and migrants. Even these will miss some plants and insects that only emerge every 5-17 years.

Herein, spatial biodiversity is reported. It suggests the environment within which and to which other biological forms respond. The premise used is that the more spatially diverse the area, the more opportunity there is for plant and animal richness.

The following indices will be reported based on data collected in the field:

The modified Simpson Index for spatial biodiversity (maximum when equal areas are in all types (D))

There are 25 families and 209 species of fish known to be found in Virginia (1983). Changes will be noted as obtained from the State wildlife information system.

The fish richness index is

The Avian richness index is

The Mammalian richness index is

The spatial Shannon-Weiner Index (for comparative uses on other areas only; using hectares and natural logarithms, base e)

The entire Owner's Manual recommendations, when being implemented, can be viewed as a "biodiversity conservation program." It is this and much more. "Biodiversity conservation" is a two-word image for a strongly-felt set of objectives listed above. There are many reasons for wanting biodiversity, but these need not be examined too carefully. An objective does exist. It can only be ignored with risk.

It is possible to increase the index, D, while promoting economic development.

The Fishery staff is attempting to develop a program for strengthening landowner capacity for natural resource management. This includes research, protected area management, finance management, strategic planning, information management, feedback, and feedforward. The landowner is encouraged to correspond about this program within The Fishery and to request announcements and to become involved..

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