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Why Diversity Matters Alan Haney When we were still a frontier society, forestry practices reflected both the abundant resources available and our growing need for timber. There were still vast areas of virgin forests in the West, and we did not understand that we were members of a finite global ecosystem. Although our need for forest products is much greater now, so is our understanding of forest dynamics. Nevertheless, the global ecosystem and many local ecosystems are rapidly being pushed to the limits of their sustainability. Thirty-five years ago, Lynton Caldwell promoted the concept of ecosystem management.2 Caldwell recognized that ecosystem management would require a substantial shift in public attitudes. While this shift is occurring, ecosystem management has become tainted in the minds of some because it is often associated with preservationism. Although there is a connection, preservationism and ecosystem management are quite different. Ecosystem management might better be called sustainable management. Roy Keene, founder of the Public Forestry Foundation, suggested we might substitute the term “ecosystem maintenance.” Both suggestions imply, correctly, that the aim of ecosystem management is to manage ecosystems such that they will continue to function well in perpetuity, and thereby continue to provide us with the services we desire from them. Ecosystem management represents a shift in the ways we practice forestry from emphasis on outputs to a focus on sustainability. Keene felt that foresters needed to shift their emphasis to what is left in the forest, not just residual trees, but also wildlife, non-commercial species, water quality, and aesthetics. As Jerry Franklin, the person credited with beginning the movement toward sustainable forestry, put it, we cannot begin an ecosystem management plan by asking how much timber we can cut. We begin by asking how to sustain or enhance the ecosystem.3 Because ecosystem management is aimed at sustainability, disagreements seem odd. Surely everyone can agree that we must manage our public lands to ensure that those who follow will have as many options for use as we have enjoyed. I believe most private forest owners also would agree that they want to manage their forests in a way that protects their sustainability. The problem arises from the obscure relationship between the characteristics of an ecosystem and its sustainability. Ecologist Frank Egler observed, “Ecosystems are not only more complex that we think, they are more complex than we can think.” This point leads us to forest diversity, the crux of understanding ecosystem sustainability. Biodiversity arguably is the most tangible handle to evaluate the condition of a forest or an ecosystem. Ecologists, however, have had trouble demonstrating cause-effect relationships between biodiversity and sustainability. Diversity is further confused by reference to vague constructs such as ecological integrity and ecosystem health. Before leaping to a conclusion, however, consider that most ecologists agree that there is a connection, at least between diversity and sustainability. Specifically, we know that:
Because of niche overlap, we also know that some species can be eliminated or substantially reduced without significantly reducing or eliminating functions or structure. Also, many ecosystems, especially in temperate regions, are remarkably resilient and maintain their productivity for extended periods with less than a full complement of native species. Consequently, foresters have a lot of uncertainty about sustainability but a broad window of opportunity in which to operate. The uncertainty, however, means we also do not have a very clear indication of critical thresholds. Conservation biologists have pointed out that, given this level of uncertainty, it is prudent to be very conservative in our protection of diversity. This leads to the argument that we cannot afford to lose any species from our forests and, in the extreme, we should not attempt to manipulate nature at all, the preservationist’s viewpoints. In my opinion, ecological evidence suggests that in most ecosystems we have plenty of management options between the extremes of reckless exploitation on one hand and hands-off on the other. Here are some basic principles that should guide our management:
- recognizing and protecting ecosystem structures and processes at all scales, from local sites to landscapes, and - consideration in our decisions for both short-term and long-term consequences; and - control of exotic species that commonly lead to loss of native diversity. These principles cannot be implemented, in most cases, without cooperation and coordination among neighboring landowners, including both private and public managers. This is particularly true where forests are more fragmented and managed in relatively small (e.g. < 1000 or more acres) parcels. Thus, protection of diversity and sustainable forest management require community cooperation in most landscapes. Woodlands are ecosystems that are under stress, from introduced pests such as the emerald ash borer and garlic mustard to global climate change. Unless we have some understanding of these ecosystems and practice sustainable forestry, forests may deteriorate until we blindly cross one threshold of nonsustainability after another. We all have an ethical responsibility to manage our forests sustainably and to help educate and cooperate with our neighbors. ____________________ 1Adopted from an article by the author published in Woodland Management (Summer 1996). 2Caldwell, L. 1970. The ecosystem as a criterion for public land policy. Natural Resources Journal 10(2): 203-221. 3Franklin, J. 1996. Ecosystem management: an overview. In: Boyce, M.S., and Alan Haney (eds.) Ecosystem Management: Application for Sustainable Forest and Wildlife Resources. Yale University Press. New Haven, Ct.
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