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Defining Sustainable Forestry
By Gregory H. Aplet, Nels Johnson, Jeffrey T. Olson, V. Alaric Sample
ISLAND PRESSCopyright © 1993 The Wilderness Society
All rights reserved.
Sustainable Forestry or Sustainable Forests?
Reed F. Noss College of Forestry, University of Idaho
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Sustainability is the motherhood and apple pie of modern conservation. We invoke the concept in discussions of economic development, agriculture, forestry, fisheries, wildlife management, and general relationships between human beings and nature. Sustainability is a goal that no one, from the most determined of environmentalists to the most aggressive of developers, can oppose (at least not in public). If an enterprise is sustainable, it is good. If it is not sustainable, then we had better replace it quickly with something that is. Anybody who opposes sustainability must be either evil or deranged.
Amidst all the clamor about sustainability, has anyone stopped to ask, Is it true? Can we really sustain all of those exploitative activities forever? Can we keep on cutting timber, grazing cows, catching fish, and building houses, eternally, if we do these things right? With five and a half billion people on Earth? The situation is particularly ironic when those of us in the rich countries tell people in the Third World that they must practice sustainable development when we have never demonstrated it ourselves. We got rich on unsustainable development.
But I should not be too cynical. Sustainable forestry, and perhaps even sustainable development, are possible in principle. The sustainability concept, however, as it has been applied so far, is utterly anthropocentric—and that is where it is in need of significant revision. We might very well sustain an economic activity for a long time but yet lose many things not of immediate concern to us in the process. Some of those things we and our descendants will never miss, for we never knew they were there. Ecosystems do contain some functional redundancy. To a point (although we do not know precisely where that point is), ecosystems can be simplified and brought under our control and yet still function in the sense of cycling nutrients and transforming energy into useful products. They might even be aesthetically attractive—a pastoral scene, for example—though impoverished in many ways that we do not see or understand.
My major point in this chapter is that sustaining forestry is not the same as sustaining forests. Forestry has been largely concerned with silviculture, defined as "that branch of forestry which deals with the establishment, development, care, and reproduction of stands of timber" (Tourney 1947). The aim of silviculture, according to Tourney, is the "continuous production of wood." But forests comprise much more than wood and other products for human consumption, much more even than the "public service" functions of climatic regulation, water supply, pest control, gene banks, or recreational opportunities. What we or future human generations can afford to lose is not the only consideration. Forests are valuable and must be sustained for their own sake. Until we acquire such an attitude, the sustainability concept may be a smoke screen, behind which we continue to chip away at our biotic heritage.
SUSTAINABILITY AND BIODIVERSITY
Sustainability and biodiversity compete for the title of "biggest buzzword in conservation." Most of us would agree that these concepts should be complementary rather than competing. But which concept is more fundamental? Biodiversity is sometimes seen as a means to an end, on the one hand as a genetic warehouse from which we can draw all sorts of useful products and, on the other hand, as an indicator of environmental health. A diverse environment is a healthy and stable one, or so the old paradigm goes. Although the diversity-stability relationship is much more complicated than we once thought, no one will deny that, when an ecosystem is impoverished (such as when a diverse forest is converted into a cattle pasture or cornfield), it is often put in a precarious condition maintained only by vast inputs of cultural energy, if it can be maintained at all.
An alternative view of biodiversity, and perhaps the unspoken majority view among biologists and environmentalists, is that biodiversity is an end in itself. We are interested in preserving the full richness of species, genetic material, and ecosystems on Earth because they have an inherent worth that overshadows any use we might make of them. The intrinsic value and instrumental value conceptions of biodiversity are not mutually exclusive. We can value forests for their own sake and use them too, but not every forest and not for everything.
Another critical consideration is that biodiversity is not just a numbers game. At a global scale, maintaining maximal species richness is a very important goal. At any smaller scale, however, quality is more important than quantity. Increasing the sheer number of species in a landscape, as we can do quite handily with checkerboard clear- cutting, for example, does not necessarily contribute to biodiversity conservation goals. In fact, as we artificially increase species richness at a local scale by favoring weedy, opportunistic species that thrive with human disturbance, we risk depletion of global biodiversity as sensitive and endemic species are lost and every place begins to look the same (Noss 1983). Diversification can all too easily become homogenization.
One way to look at the relationship between biodiversity and sustainability is that biodiversity provides enduring options for sustainable management. As Leopold (1949) noted, "to keep every cog and wheel is the first precaution of intelligent tinkering." Particularly when the future is unpredictable, as it surely is now with human population growth, irrational energy policies, climate change, ozone depletion, and other global problems, it makes sense to maintain as many options as possible. A landscape with a great diversity of habitats, species, and genotypes is likely to be more adaptable to change than is a monoculture.
A most important question we must ask with regard to sustainability is What do we wish to sustain and why? This is essentially an issue of goal setting. We need to pay more attention to where we wish to head with our land management programs and to what values are behind those objectives. If our goal is only to maintain an approximately even flow of wood products, then we have a seemingly easier task than if we have to worry about sustaining the food webs and nutrient cycles that maintain soil productivity. Of course, in the long run we must think about maintaining soils and ecological processes if we want a sustained yield of wood products. Maintaining watershed integrity may require even more restraint.
The National Forest Management Act (NFMA) of 1976 has sustainability provisions. It states that timber is to be cut only where "soil, slope, or other watershed conditions will not be irrevocably damaged and where land can, with assurance, be restocked within five years after logging." The regulations implementing the NFMA require the Forest Service to manage the land so as not to impair its multiple-use productivity and so as to consider all renewable resources (Norse et al. 1986). Although the NFMA guidelines appeal more to an agricultural than to an ecological criterion for sustainability, ecological thinking does underlie the NFMA, more so than for virtually any other law on the books. Despite all of the rhetoric about multiple use, however, the overriding goal driving the management of national forests still seems to be getting the cut out.
The ecosystem argument for sustainability is good as far as it goes, but it does not guarantee that native biodiversity will persist. Ecological arguments can suggest many different things, depending on the goal. We may be able to design a forest that provides wood products in perpetuity, soil and watershed integrity, and persistence of most native species but fails to maintain highly sensitive species, such as grizzly bears or Florida panthers, or suitable conditions for continued evolution of species. And there are still other qualities of forests that are seldom considered in forestry or ecology but yet are important to us in immeasurable ways. These other values include wildness and naturalness. A perfectly functioning tree farm, even if quite diverse in native species and genotypes, is not good enough; it is too much like a machine.
Sustainability, then, is a multifaceted and relative concept. It must be defined in terms of (1) time period (are we sustaining forests for two, three, or four rotations or for millennia?) and (2) proportion of ecosystem structure, function, and composition maintained (Franklin et al. 1981). Structure includes dead wood that is not salvaged, function includes wildfires and floods that are sometimes inconvenient for humans, and composition includes species, such as large carnivores, that do not like to have us around and others, such as soil invertebrates and fungi, that most people find very boring. Managed forests should be compared in terms of how well they maintain all of their native components over time, not just those that are convenient for human society.
Exploited forests must be measured against some kind of standard to assess their relative sustainability. The best control area against which exploited forests can be compared is the natural, unexploited forest, as was recognized over fifty years ago by Leopold (1941), who stated that wilderness provides a "base-datum of normality, a picture of how healthy land maintains itself as an organism." Unexploited forests also provide qualities of wildness and naturalness that no exploited forest can match. But we can compare exploited forests in terms of these seemingly intangible qualities as well. Anderson (1991) offered three criteria for assessing the relative naturalness of any area: (1) the amount of cultural energy required to maintain the system in its present state, (2) the extent to which the system would change if humans were removed from the scene, and (3) the proportion of the fauna and flora composed of native versus nonnative species. Forests that can take care of themselves, would change little if we left them alone, and are made up of native species are more natural—and, I submit, more sustainable—than are humanized forests. So naturalness and sustainability may not be so far apart as conservation criteria.
We tend to think of sustainable forestry as sustainable exploitation. But this is an arrogant view and clearly not the whole picture. Acknowledging that forests must and should be used by society for a variety of products and services, I believe that it is also essential that large areas be left essentially unmanaged except for the protective and restorative management now needed for all but the most remote regions on Earth. A sustainable forest, at a regional scale, contains unexploited as well as exploited areas. In our rush to experiment with the latest techniques in New Forestry, I fear we are forgetting about the need for control areas, without which our experiments are meaningless. Without a healthy dose of humility and restraint, the sustainability concept can be dangerous.
Forest management includes a wide range of practices, from intensive tree farming to leaving areas alone. Some people find the whole concept of management insolent and pernicious, but I am afraid that we are stuck with it in the short term and with five and a half billion people on Earth. In any case, management and stewardship are at least potentially a big step above earlier practices of cut-and-run exploitation.
The effects of forest management on biodiversity differ widely among practices and circumstances. Management may be (1) negative, threatening biodiversity by failing to maintain or mimic natural ecosystem processes and take into consideration the needs of sensitive species; (2) neutral, if it emulates nature and substitutes for natural disturbance-recovery cycles; or (3) positive, if it is oriented toward restoring forests abused by past management practices. Most of us will agree that negative forest management must be phased out as quickly as possible, everywhere, and be replaced by management that is at least neutral with respect to biodiversity and, wherever possible, positive, being concerned with healing and nurturing abused forests.
IDENTIFYING TRAJECTORIES OF IMPOVERISHMENT
How are we to set objectives for protecting biodiversity in managed forests and for healing abused forests? A first step is to identify the trends or trajectories of landscape change that have been associated with biotic impoverishment in a region. Biotic impoverishment in forest landscapes can be linked to habitat changes that exceed the adaptive capacities of at least some native species. These habitat changes represent a shift in landscape conditions to a present condition that is less favorable to native biodiversity than the natural or historic condition of the landscape. Although natural condition is notoriously difficult to define and is always changing, we do not have to quantify natural condition to identify the ways in which the present landscape has departed from it and how those changes threaten native biodiversity.
The shift from natural conditions affects several characteristics of the forest landscape, notably stand age distribution, structural diversity, fragmentation, fire regimes, road density, and rare species. The pathway of change in each of these characteristics can be thought of as a trajectory from the natural to the managed conditions, and the landscape as a whole is transformed along several trajectories simultaneously (e.g., from older to younger stands, from complex to simple stands, and from contiguous to isolated patches). These trajectories are often intercorrelated but can vary independently of one another and proceed at different rates. There will be regional and local differences in the strength of each trend, and many landscapes will demonstrate only a subset of these trends. In some landscapes, other trends, such as livestock grazing or air pollution, may be more important than the seven described below.
Many unexploited forests are dominated by older age classes. An individual landscape may shift radically in age class distributions over time because of stand-replacing disturbances and subsequent succession; therefore, age class (seral stage) distributions are best estimated at a regional scale. In the Pacific Northwest, it is estimated that some 60 to 70 percent of commercial forest land in the Douglas fir region in the early 1800s was old growth (Franklin and Spies 1984). Old growth was also the most abundant seral stage of the eastern deciduous forests (Greller 1988) and the longleaf pine forests that dominated the southeastern coastal plain (Platt, Evans, and Rathbun 1988), among others.
With logging, forest age classes across these regions shifted to favor younger stages. No more than 13 percent of the presettlement old growth remains in the Pacific Northwest (Norse 1990); the figure is generally smaller in other regions of the United States, excluding Alaska. With short rotations for wood fiber production, dominance by younger age classes persists indefinitely. The consequences of this shift are most severe for those species closely associated with old growth, such as the northern spotted owl and a number of other species in the Northwest (Carey 1989) and the red-cockaded woodpecker in the Southeast (Jackson 1971).
With conversion of natural forests to plantations, stand structure is greatly simplified. Traditional clear-cutting and site preparation practices remove most of the coarse woody debris before planting. The barren site that remains differs dramatically from a stand affected by natural disturbance such as fire or windthrow. In Douglas fir forests of the Northwest, research has demonstrated that snags, downed logs, and surviving trees persist through much of the successional sequence after a natural disturbance and provide sites for plant regeneration, water retention, and nutrient cycling, as well as wildlife habitat (Franklin et al. 1981; Maser et al. 1988).
Douglas fir plantations with reduced structural diversity have been shown to contain reduced species richness of breeding birds, small mammals, and amphibians and greatly reduced abundances of birds and amphibians relative to natural forests of any age in Oregon (Hansen et al. 1991). In Florida, species richness and density of breeding birds decline when natural longleaf pine forests are converted to simplified plantations (Repenning and Labisky 1985).
Excerpted from Defining Sustainable Forestry by Gregory H. Aplet, Nels Johnson, Jeffrey T. Olson, V. Alaric Sample. Copyright © 1993 The Wilderness Society. Excerpted by permission of ISLAND PRESS.
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