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BioDiversity PART 8 RESTORATION ECOLOGY: CAN WE RECOVER LOST GROUND?
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BioDiversity Restored prairie at the University of Wisconsin Arboretum, Madison. Inset shows members of the Civilian Conservation Corps planting at this site in the late 1930s. Photo courtesy of the Unwersity of Wisconsin Arboretum and Archives.
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BioDiversity CHAPTER 35 ECOLOGICAL RESTORATION Reflections on a Half-Century of Experience at the University of Wisconsin-Madison Arboretum WILLIAM R.JORDAN III Editor, Restoration & Management Notes, The University of Wisconsin-Madison Arboretum, Madison, Wisconsin So far, in this volume and in thinking and discussions about the conservation of biological diversity generally, the emphasis has been on preservation of what we already have. This makes sense. Preservation obviously has a critical role to play in the conservation of diversity. At the same time, however, it is clear that by itself preservation is not an adequate strategy for conserving diversity. At best, preservation can only hold on to what already exists. In a world of change, we need more than that. Ultimately, we need a way not only of saving what we have but also of putting the pieces back together when something has been altered, damaged, or even destroyed. Consider, for example, that vast areas of both land and water have already been profoundly altered by human activities ranging from agriculture to mining and construction and to various forms of pollution; barring a catastrophe on the scale of nuclear war, human-caused alterations of natural and wilderness areas will continue indefinitely; certain kinds of change—notably changes in climate—are beyond human control, and they in turn will inevitably change even those areas we have succeeded in preserving; existing wilderness preserves are often inadequate in size or are suboptimal in shape or design; in many cases, their value as reservoirs of biodiversity could be dramatically increased by relatively modest increases in size, which could be achieved by active reconstruction of communities around their borders;
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BioDiversity numerous species are already on the brink of extinction and their habitats have been reduced to a remnant or perhaps eliminated completely, so that their only hope for long-term survival is the re-creation of their habitat by human beings; and the conservation of species ex situ will have little environmental value in the long run unless we find ways of providing habitat for them, often by creating it on disturbed sites. All these considerations push us, unwillingly it seems at times, beyond a preoccupation with preservation, either in situ or ex situ, as the single strategy for the long-term conservation of diversity and toward a recognition of the importance of an active role for our species in reversing change or repairing damage. Unless, for example, we are prepared simply to write off disturbed lands as potential contributors to diversity, we are going to have to take seriously the problem of increasing diversity on these lands. Similarly, the inevitability of further change, including changes in climate, clearly implies that in order to preserve many communities over the long haul we are going to have to learn not only how to manage them but even how to move them around (Jordan et al., in press). And this brings us to the area of environmental healing, or ecological restoration, which is the subject of this section. PIONEERING RESTORATION AT THE UNIVERSITY OF WISCONSIN-MADISON ARBORETUM The starting point for this discussion will be the experience of the University of Wisconsin-Madison Arboretum, where research on restoration of ecological communities native to Wisconsin and the upper Midwest has been under way since 1934. Here, under the early leadership of Aldo Leopold and John Curtis, intensive restoration has been carried out on several hundred hectares of land, most of which had been seriously degraded by farming, logging, and sporadic development during the preceding century. Gradually, 40 hectares of tallgrass prairies have been restored on degraded pasture and plowland. A small xeric prairie has been created on an artificially constructed limestone outcropping. Red and white pine forests and boreal forests have been established on old pasture sites, and two types of maple forests are being developed by underplanting existing oak forests in which the understory had been depleted by grazing. The early stages of this effort were carried out by Civilian Conservation Corps crews working out of a camp on the site between 1935 and 1941. More recent work has been carried out by University of Wisconsin-Madison researchers and by the Arboretum staff. In general, the intensity of the restoration effort declined dramatically after 1941, though work continues, and indeed the need for ongoing restoration and management is one of the fundamental lessons that has emerged from the Arboretum’s experiences. Overall, this has been a pioneering effort, and the Arboretum’s collection of restored and partially restored communities is now the oldest and most extensive of its kind anywhere in the world. Even more to the point, however, because of the Arboretum’s experience, it is possible to make a number of observations about
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BioDiversity the nature of restoration, about its potential and its limitations as a strategy for conserving biological diversity, and about the environmental and social conditions under which it is likely to be feasible. TECHNICAL, ECOLOGICAL FEASIBILITY The first lesson that one might derive from this experience is that it is indeed possible, at least under certain circumstances, to re-create reasonably authentic replicas of some native ecological communities (Blewett, 1981). For example, the Arboretum’s two restored tallgrass prairies (Curtis and Greene prairies) now include areas believed to resemble quite closely prairies native to the area—at least with respect to floristic composition. In other words, most of the appropriate vascular plants are present; they are present in more or less the right proportions and associations; and the number of inappropriate plants—that is, exotics or plants not native to the tallgrass prairies of this area—is small. On the other hand, there are large areas on these prairies where ecological or historic authenticity is relatively low and where various exotic species are abundant. Certain of these species have proved to be extremely difficult to remove or control. Some have turned out to be capable of invading the more or less intact prairie community, often at the expense of the native plants. As a result, it is now abundantly clear that the problem of dealing with exotics is an ongoing one and that the struggle will in many instances be unending. Undisturbed natural communities are also vulnerable to invasions by exotic species but, in general, probably less so than communities in the process of being restored. Without doubt, this has turned out to be a major problem facing restorationists. In addition, the restoration program at the Arboretum has strongly emphasized revegetation, far less attention being paid to the reintroduction of animal species. This is frequently the case in restoration and land reclamation projects, since the assumption is often made that the appropriate animals will find their way into the community once it has developed to a certain point. But this does not always happen for complex reasons that include the size of the communities, their uneven quality, and their isolation from existing animal populations. An instance of this now appears to have occurred in the Arboretum’s restored southern maple forest, where ommission of an ant species that normally aids the dispersal of the seeds of certain herbaceous plants, such as bloodroot (Sanguinaria canadensis) and wild ginger (Asarum canadense), has resulted in the development of these species into peculiar, dense patches (Woods, 1984). A related problem with restored communities generally is their small size, which can directly influence their ecological quality. Certain animals, for example, may not inhabit restored communities simply because these communities are often too small. This is a major reason why few if any restored prairies include buffalo, for example. At present, the prairie at Fermilab in suburban Chicago is probably the largest restored tallgrass prairie in existence (Nelson, 1987). Of course, this nearly 240-hectare prairie is still very small in comparison to the millions of hectares of prairie that existed in this area at the time of European settlement, and its ability to support populations of large native animals is at best problematic.
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BioDiversity In addition to the more conspicuous defects in the composition of restored communities, there are numerous features, such as soil structure and chemistry, composition of soil flora, populations of less conspicuous animals (including insects), and various aspects of ecosystem function, that in many instances may not be authentic. Only rarely have these been studied in any detail. On the positive side, however, the Arboretum’s restored communities have brought back into the landscape numerous plants and animals that had become rare or had even been eliminated locally. The entire project certainly represents an enormous contribution to what might be called the native diversity of the Madison area. The Arboretum’s restored tallgrass prairies, for example, are now among the largest prairies in Wisconsin, a state that had some 4.8 million hectares of prairie and savanna at the time of European settlement (Curtis, 1959). These prairies alone include more than 300 species of native plants. Some of them, including plants such as big bluestem grass (Andropogon gerardi), compass plant (Silphium laciniatum), and yellow coneflower (Ratibida pinnata), were extremely abundant in presettlement times, often dominating whole landscapes, but were virtually eliminated from the area by the time the restoration efforts at the Arboretum began. These now flourish in the restored communities, which also provide habitat for numerous rare species. Examples from the Arboretum’s collection include such rarities as the white-fringed orchid (Habenaria leucophaea), prairie parsley (Polytaenia nuttallii), smooth phlox (Phlox glaberrima), and wild quinine (Parthenium integrifolium)—all considered threatened or endangered, at least for the state. In general, the Arboretum itself probably has more biological diversity than any other area of comparable size in the state. This is due largely to the presence of the various restored communities. In short, the Arboretum’s experience shows that restoration of some native communities may be technically feasible under certain conditions. The ecological quality of the resulting communities may vary, but under proper conditions, it may actually be quite high, and restored communities may often resemble the historic community chosen as a model quite closely, at least in floristic composition. SOCIAL, ECONOMIC FACTORS At the same time, the experience of the Arboretum raises a number of questions about the cost of such projects and the social, political, and economic feasibility of carrying them out. Thus, in considering the environmental significance of the Arboretum’s restoration efforts, one should keep in mind that these efforts have been carried out under conditions that clearly limit their relevance to other situations. These conditions include first of all the fact that the Arboretum itself is part of a major university and that its work has been performed primarily for scientific and academic reasons. In other words, from the very beginning, this effort has benefited from its academic setting and has been justified as an experiment or as a way of creating communities for research, rather than as a way of coping with environmental, much less economic, problems. The second set of conditions that have contributed to the success of the Arboretum project were those directly related to the economic and ecological con-
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BioDiversity ditions of the 1930s, notably the Great Depression and the Dustbowl. Together, these national calamities provided conditions (specifically, cheap land, free labor in the form of the Civilian Conservation Corps, and an incentive for ecological restoration) that proved crucial to the development of the Arboretum, but that have also reduced its value as a model for carrying out restoration projects in the real world outside academia. This point carries us outside the little world of the Arboretum to the larger world, where we have to ask a crucial question: What good is restoration? Is it likely to prove merely an academic pursuit or a pastime for environmentalists who happen to be interested in an unusual form of gardening? To just what extent and under what conditions can restoration be expected to contribute in a significant way to the conservation of diversity? These questions have not yet been dealt with systematically, as far as I am aware. But it is important that we begin to take them seriously. In general, given the interrelatedness of everything on Earth and the inevitability of change, it would seem that an ineluctable logic argues for the importance of restoration as part of any comprehensive strategy for the conservation of biological diversity. Critical as it may be as part of such a strategy, preservation has serious defects. Basically, it is a one-way strategy that offers no way of responding to change or recouping losses. By itself, any such approach is clearly inadequate because in a changing world the quality of the environment is ultimately going to depend not simply upon the amount of land we manage to set aside and to preserve but upon the equilibrium we are able to maintain between the forces of destruction—or change—on the one hand and the forces of recovery on the other. All things considered, and despite its various limitations, it seems likely that restoration will ultimately play an important role in determining the position of this equilibrium. This being the case, the questions raised above and a whole host of corollary questions and issues take on a great deal of urgency. Can we restore ecological systems? And if so, how authentic will the results be? Which communities lend themselves to restoration, and which are likely to prove more difficult—or even impossible—to restore? To what extent can we hope to re-create communities specifically designed to provide habitat for rare and endangered species? What needs to be known in order to restore a system effectively—and efficiently? What is the state of the art for the restoration of various communities, and what currently limits the effectiveness of restoration techniques for these systems? What sorts of research need to be undertaken in order to refine these techniques? Beyond these questions about the technical feasibility of restoration, there are the various social, economic, and political questions: How much will it cost? Who will be expected to pay for it, and why? How will the costs compare with those of preservation or with the natural recovery of disturbed systems? What incentive will society have for restoring naturally diverse communities rather than for simply reclaiming land for some other purpose such as agriculture? In general, what incentives can be found for restoring communities—incentives that will ensure that restoration is actually accomplished and that its potential for contributing to biological diversity is effectively exploited? In fact, there are a number of such incentives, including some traditional ones such as the creation of habitat for fish and game and the use of prairies as pasture
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BioDiversity and rangeland. There are also important aesthetic incentives in park and wilderness management and in landscape architecture. But restored communities may well have other economic values that have not yet been fully identified or widely recognized. Examples include development of wetlands to control water distribution and quality (Holtz, 1986), of prairies to rehabilitate soils degraded by agriculture (Miller and Jastrow, 1986), and of forests as part of a program of sustained-yield timber production (Ashby, 1987). Applications such as these at least suggest ways in which restoration might eventually prove critical as a way of reintegrating native communities into the economies of developed nations, in the process returning them to the landscape on a large scale. These questions are addressed in the four chapters that follow. The first two are devoted mainly to defining the state of the art of ecological restoration for two community types. In the first of these, Chapter 36, Joy Zedler discusses restoration of a temperate zone community, the tidal wetland. In Chapter 37, Chris Uhl addresses the much-neglected subject of tropical forest restoration. The following two chapters turn to the more socially oriented aspects of the business of restoration. In Chapter 38, John Cairns looks at disturbed lands as opportunities for increasing local and regional biodiversity through restoration. In Chapter 39, John Todd presents some ideas about creating a social, political, and economic context for restoration projects. REFERENCES Ashby, C. 1987. Forests. Pp. 89–108 in M.E.Gilpin, W.R.Jordan III, and J.D.Aber, eds. Restoration Ecology: A Synthetic Approach to Ecological Research. Cambridge University Press, New York. Blewett, T.J. 1981. An Ordination Study of Plant Species Ecology in the Arboretum Prairies. Ph.D. Thesis, University of Wisconsin-Madison. 354 pp. Curtis, J.T. 1959. The Vegetation of Wisconsin. University of Wisconsin-Madison Press. 657 pp. Holtz, S. 1986. Bringing back a beautiful landscape—wetland restoration on the Des Plaines River, Illinois. Restoration & Management Notes 4:56–61. Jordan, W.R. III, R.L.Peters, and E.B.Allen. In press. Ecological restoration as a strategy for conserving biological diversity. Environ. Manage. Miller, R.M., and J.D.Jastrow. 1986. Soil studies at Fermilab support agricultural role for restored prairies. Restoration & Management Notes 4:62–63. Nelson, H.L. 1987. Prairie restoration in the Chicago area. Restoration & Management Notes 5(2). Woods, B. 1984. Ants disperse seed of herb species in a restored maple forest. Restoration & Management Notes 2:18.
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BioDiversity CHAPTER 36 RESTORING DIVERSITY IN SALT MARSHES Can We Do It? JOY B.ZEDLER Professor of Biology, San Diego State University, San Diego, California Along the U.S. coastline, development has reduced the area of coastal wetlands and endangered certain wetland-dependent species. Despite the threats to biodiversity, development of wetland habitat is still permitted by regulatory agencies if project damages can be mitigated by improving degraded wetlands or creating new wetlands from uplands. For example, the California Coastal Act allows one-fourth of a degraded wetland to be destroyed if the remaining three-fourths is enhanced. The expectation is that increased habitat quality will compensate for decreased quantity. The concept sounds reasonable, but biodiversity is continuing to decline. Why? First, the process allows a loss of habitat acreage. Second, there is no assurance that wetland ecosystems can be manipulated to fulfill restoration promises. The magnitude of the problem is well illustrated by examples from southern California, where more than 75% of the coastal wetland acreage has already been destroyed, where wetland-dependent species have become endangered with extinction, and where coastal development pressures rank highest in the nation. This chapter reviews several restoration plans and implementation projects and suggests measures needed to reverse the trend of declining diversity. RESTORATION PLANS Several large development projects in southern California wetlands have recently been approved by the California Coastal Commission (see Figure 36–1). Three federally endangered species are affected by such projects: the California least tern (Sterna albifrons browni), light-footed clapper rail (Rallus longirostris levipes), and salt marsh bird’s beak (Cordylanthus maritimus spp. maritimus; see Figure 36–2).
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BioDiversity FIGURE 36–1 Sites of some coastal development projects in southern California. In all, there are 26 coastal wetlands between Point Conception and the Mexico-U.S. border. FIGURE 36–2 The salt marsh bird’s beak grows near the upper wetland edge. As an annual plant, its seeds germinate after winter rainfall to maintain the population; as a hemiparasite, its seedlings grow roots that can attach to those of other plants, thereby increasing its supplies of water and nutrients. Photo by J.Zedler.
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BioDiversity There would also be an impact on the Belding’s Savannah sparrow (Passerculus sandwichensis beldingi), which is listed as endangered by the state, and on several plant species of regional concern (Ferren, 1985). Projects That Show Losses in Wetland Area At Bolsa Chica Wetland, more than 1,200 acres (480 hectares) of lagoonal wetland will be reduced to 951 acres (366 hectares) of restored wetland (California State Coastal Conservancy, 1984). Mitigation plans are not final, but the draft concept includes cutting an ocean inlet to serve a new marina. Inland from the marina are sites for restored wetlands with controlled tidal flushing. Uplands designated as “environmentally sensitive habitat areas” that lie within the lowland area and that will be destroyed during development are to be relocated adjacent to the restored wetland in a bluff-edge (linear) park. The draft concept plan accommodates development, but does not ensure maintenance of biodiversity. The restoration activities are based on the assumption that habitat values can be created and moved about at will. In Los Angeles Harbor, about 400 acres (160 hectares) of shallow water fisheries habitat will be filled to construct new port facilities. At this project site, there is no habitat available to be restored—all the wetlands have been filled or dredged. Thus, off-site mitigation has been approved. Batiquitos Lagoon, more than 80 miles (130 kilometers) south of Los Angeles, will be dredged to create deep-water habitat and increase tidal flushing. According to plans (California State Coastal Conservancy, 1986), the net loss of aquatic habitat in Los Angeles will be mitigated by altering (not increasing) habitat elsewhere. The dredging of Batiquitos Lagoon will remove sediments and, at least temporarily, solve the occasional problems of algal blooms (odors and fish kills after sewage spills). However, maximizing tidal flushing at Batiquitos Lagoon (to replace fisheries habitat in Los Angeles Harbor) will destroy existing salt marsh habitat (Figure 36–3) and reduce the area of shallow water and mudflat habitat. The mitigation plan contains two strikes against biodiversity—the loss of area and the loss of existing functional wetland types. At Aqua Hedionda Lagoon, about 14 acres (5.6 hectares) of wetland were filled to build a four-lane road. The mitigation plan (U.S. Army Corps of Engineers, 1985) promised to enhance diversity and increase the functional capacity of the lagoon. Brackish-water ponds were planned for a wetland transitional area (itself a rare habitat type); a 2-acre (0.8-hectare) dredge spoil island was to be built for bird nesting; and a 7-acre (2.8-hectare) debris basin was proposed within a riparian area to reduce sedimentation into the lagoon. Flaws in the plan became clear when construction of the brackish ponds began. Pits were dug to a depth of 6 feet (1.8 meters) without encountering groundwater. Areas that were modified included transition habitat, pickleweed marsh (Figure 36–4), brackish marsh, and riparian habitat. The wetland lost both acreage and habitat quality. All these projects show a net loss in wetland habitat area. Proponents argue that the lost areas are already degraded. However, they could be enhanced to maintain biodiversity. The fact that four wetland-dependent species have become endangered in Southern California while coastal wetlands have shrunk by 75% indicates a cause-effect relationship. There is some minimum area required to
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BioDiversity dangered, or threatened species. Damaged ecosystems that may act as ecological barriers (e.g., power line right of ways) can be converted to “bridges” between the ecosystems on either side. Finally, they can be used to recharge and possibly purify our groundwater aquifers. None of these desirable events will happen unless the present prescriptive regulations on rehabitation of damaged ecosystems are made more flexible to encourage experimentation. The sizable information base needed for effective ecosystem rehabilitation will not be generated until more ecologists are willing to work on damaged ecosystems. It is probably not an exaggeration to say that much of the planet is occupied by partially or badly damaged ecosystems. Restoring them is probably the best means of increasing diversity. If we put as many resources and as much energy into restoring this planet as we have into the space program, Curry’s (1977) vision of reinhabiting Earth might become a reality. REFERENCES Bradshaw, A.D. In press. Alternative end points for reclamation. In J.Cairns, Jr., ed. Rehabilitating Damaged Ecosystems. CRC Press, Boca Raton, Fla. Brooks, R.P., D.E.Samuel, and J.B.Hill, eds. 1985. Wetlands and Water Management on Mined Lands. Proceedings of a conference, October 23–24, 1985, Pennsylvania State University. Pennsylvania State University, University Park. 393 pp. Bruns, D. In press. Restoration and management of ecosystems for nature conservation in West Germany. In J.Cairns, Jr., ed. Rehabilitating Damaged Ecosystems. CRC Press, Boca Raton, Fla. Brussard, P.F. 1982. The role of field stations in the preservation of biological diversity. BioScience 32(5):327–330. Cairns, J., Jr., ed. 1980. The Recovery Process in Damaged Ecosystems. Ann Arbor Science Publishers, Ann Arbor, Mich. 167 pp. Cairns, J., Jr. 1985. Keynote address: Facing some awkward questions concerning rehabilitation management practices on mined lands. Pp. 9–17 in R.P.Brooks, D.E.Samuel, and J.B.Hill, eds. Wetlands and Water Management on Mined Lands. Proceedings of a conference, October 23–24, 1985, Pennsylvania State University. Pennsylvania State University, University Park. Cairns, J., Jr. 1986. Restoration, reclamation, and regeneration of degraded or destroyed habitats. Pp. 465–484 in M.Soulé, ed. Conservation Biology: The Science of Scarcity and Diversity. Sinauer Associates, Sunderland, Mass. Cairns, J., Jr. 1987. Disturbed ecosystems as opportunities for research in restoration ecology. Pp. 307–320 in W.R.Jordan III, M.E.Gilpin, and J.D.Aber, eds. Restoration Ecology: A Synthetic Approach to Ecological Research. Cambridge University Press, New York. Cairns, J., Jr. In press. Restoration ecology: The new research frontier. In J.Cairns, Jr., ed. Rehabilitating Damaged Ecosystems. CRC Press, Boca Raton, Fla. Curry, R.R. 1977. Reinhabiting the earth: Life support and the future primitive. Pp. 1–23 in J. Cairns, Jr., K.L.Dickson, and E.E.Herricks, eds. Recovery and Restoration of Damaged Ecosystems. University Press of Virginia, Charlottesville. Elias, R., Y.Hirao, and C.Patterson. 1975. Impact of present levels of aerosol Pb concentrations on both natural ecosystems and humans. Pp. 257–272 in International Conference on Heavy Metals in the Environment, October 27–31, 1975. Toronto. Janzen, D.H. In press. Guanacaste National Park: Tropical ecological and cultural restoration. In J.Cairns, Jr., ed. Rehabilitating Damaged Ecosystems. CRC Press, Boca Raton, Fla. Mabbutt, J.A. 1984. A new global assessment of the status and trends of desertification. Environ. Conserv. 11:103–115. Marsh, P.C., and J.E.Luey. 1982. Oases for aquatic life within agricultural watersheds. Fisheries 7(6):16–19, 24. NRC (National Research Council). 1981. Testing for Effects of Chemicals on Ecosystems. National Academy Press, Washington, D.C. 103 pp.
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BioDiversity Noss, R.F. 1983. A regional landscape approach to maintain diversity. BioScience 33(11):700–706. Novak, J.T., W.R.Knocke, M.S.Morris, G.L.Goodman, and T.Jett. 1985. Evaluation of an acidic waste site cleanup effort. Pp. 111–120 in Proceedings of the 40th Industrial Waste Conference. May 14–16, 1985, Purdue University, West Lafayette, Ind. Butterworth, Boston. Rapport, D.J., C.Thorpe, and H.A.Regier. 1980. Ecosystem medicine. Pp. 179–182 in J.B. Calhoun, ed. Perspectives on Adaptation, Environment and Population. Praeger Scientific, New York. Rapport, D.J., H.A.Regier, and C.Thorpe. 1981. Diagnosis, prognosis and treatment of ecosystems under stress. Pp. 269–280 in G.W.Barrett and R.Rosenberg, eds. Stress Effects on Natural Ecosystems. Wiley, Chichester, United Kingdom. Taub, F. 1969. Gnotobiotic models of freshwater communities. Vehr. Internat. Verein. Limnol. 17:485–496. Vandenbusche, D. 1981. The Gunnison Country. Vandenbusche, Gunnison, Colo. 472 pp. Vitousek, P.M., P.R.Ehrlich, A.H.Ehrlich, and P.A.Mason. 1986. Human appropriation of the products of photosynthesis. BioScience 36(6):368–373. Whittaker, R.H. 1972. Evolution and measurement of species diversity. Taxon 21:231–251.
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BioDiversity CHAPTER 39 RESTORING DIVERSITY The Search for a Social and Economic Context JOHN TODD President, Ocean Arks International, Falmouth, Massachusetts Restoration ecology is beginning to develop into two quite distinct disciplines. Although they have a lot in common, it is the differences between the two directions that are important. The first type of restoration ecology is primarily an academic field of activity in which there is an attempt to recreate authentic ecosystems of the past, particularly those that have been destroyed or modified by human alteration or abuse. There is an emphasis on selecting the correct species mix, and there is an effort to recreate the original ecological relationships at least as far as they are known. Exotic species or organisms intrinsic to other environments are shunned. Here, whether a forest or a prairie is the focus, restoration means recreating the original state both in terms of structure and species. These newly created ecosystems have the intrinsic value of maintaining important gene pools in regions where the organisms have previously flourished. They can also teach a great deal about the dynamic processes of ecosystems and succession. The pioneering work at the University of Wisconsin-Madison Arboretum (see Jordan, Chapter 35) falls into this category. The second approach to restoration ecology operates from a different set of assumptions. The overall objective is different, although much of the knowledge and techniques are comparable. A hypothetical example might help to illustrate what I mean. If a mixed-forest hillside is logged and clear-cut, then turned into pasture for cattle, later grazed by sheep, and finally allowed to lose its topsoil and erode into gullies that eventually can support only coarse grasses and thistles, it is apparent that human activity has destroyed a complex and diverse habitat and replaced it with a degraded one. The hill’s ability to support abundant life is reduced as well as its capability to underwrite economic activity. In this second category,
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BioDiversity the restoration ecologist is interested in the structure or architecture of the original forest because of its ability to do things that cannot be done by degraded and eroded soils. The forest can build soils, control the capture and release of moisture, and regulate nutrient cycles. It can withstand climatic fluxes and perturbations, and critically important to the naturalist, it can support an enormous spectrum of life forms. The forest’s dimensions extend from the tree canopy to root depths often tens of meters below the soil surface. In the hillside example, the structural, as distinct from the species-specific, restoration ecologist wants to build fertile soils, develop a water and nutrient regimen, and assemble an ecosystem that mimics the original structural integrity of the forest. The actual organisms selected to do the job may or may not be the original species. Often, the ecologist will seek out equivalent species of plants or animals that have secondary properties as well. For example, a tree species that is not adapted to the environment, but is highly valuable, provides an economic dimension to the process. Also the land restorer, like a farmer, will in most instances use a large array of biotechnologies and technological aids to orchestrate and even speed up successional and other biological processes. Sophisticated bioengineering is used to recreate the equivalent of hundreds of years of topsoil within a decade or two. The mission of the two restoration ecologies can be quite different too. Structural ecologists are willing to tolerate wider margins of uncertainties and gaps in knowledge, thereby adopting a more applied viewpoint simply because they see the planetary environmental crisis as the backdrop against which they work. To reverse desertization and habitat destruction, it ultimately will be necessary to undertake ecological restoration on a vast, planetary scale. This means that the task cannot be guided by charity based on social conscience, since there isn’t enough of either even to finance or underwrite the required backup ecological research. It is hard to avoid the conclusion that if there is to be any meaningful change, restoration ecology will have to become quite simply a major economic activity. Just as the activity seeks to recreate the forest on the hill, it will also be expecting the hill to become a sustainable and environmentally enhancing economy. A goal will be the provision of a wide variety of marketable products as a by-product of the restoration process. This is an extremely ambitious objective for a young field of endeavor, but one that is essential to its widespread application. Fortunately there exists, albeit widely scattered, the biological knowledge and field experience to build a science and practice of habitat recovery. This knowledge needs to have an ecological framework whose elements will be found in geology, climatology, agriculture, forestry, horticulture, aquaculture, limnology, research ecology, landscape architecture, and natural history, to name some of the more relevant fields of endeavor. There will also be a need to develop and adapt tools and machines for use in agriculture, earth moving, forestry, waste management, and process engineering. Returning to our hypothetical example of the eroded hillside, the first step in the restoration process would be to arrest rapid rainwater runoff and to reduce erosion. Among the many approaches that can be taken are various tillage techniques, microcatchments, contouring, and land sculpturing to regulate water move-
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BioDiversity ment. Most of the methods require sophisticated machines, careful engineering, and timed planting to be successful. Next, the degraded soils, if they are to be rebuilt quickly, will require the precise addition of minerals, fertilizers, organic matter, and vegetation to effect rapid stabilization and to increase its moisture retention. The subsequent step, intentionally recreating a forest, requires a knowledge not only of the original forest cover but also of a range of equivalent species that play an analogous role while serving as a key economic component. This ecosystem is in some respects a cross between a forest and an orchard. In our hypothetical example the wild deer of the original may be replaced by domestic animals—not necessarily cattle, however, but by the European fallow deer (Cervinae dama), which fit ecologically and are highly marketable because of the extremely low cholesterol levels in their flesh. The goal of this ecological restoration is the production of food and fiber on a commercial scale. It is not agriculture but an ecology with agricultural elements within a broader biological framework. It does not have the environmental destructiveness of monocrop agriculture or simpler agricultural systems. Its function is to restore diversity and to be bountiful in terms directly useful to humans. Linking together nature’s restoration requirements with the economic needs of people may be the only way the terrestrial fabric of the planet can be rebuilt. Large amounts of human labor are essential to the restoration process. For example, labor is needed to plant new trees and to provide them with adequate moisture and protection from weed competition or predation by grazing animals. To support the required labor, restoration ecology will have to attract capital. The future hillside ecosystem will have to be seen as a prudent investment, possibly providing favorable returns within years rather than decades. The goal of much of my research and planning over the last 15 years has been to find ways of economically underwriting the restoration and diversification process. This has involved the development of a family of biotechnologies that are in essence short-cycle ecosystems with economic by-products that also have the capacity to catalyze the longer-cycle restoration processes. These biotechnologies have been proven successful and in some contexts have been shown to be cost-effective and economically feasible (Todd and Todd, 1984). We have not yet had the opportunity to integrate all the subsystems into a full-scale restoration project, but an outline of a restoration project in the Mediterranean has been prepared (Todd, 1983, 1984). In addition, projects for the west coast of Costa Rica and the Atlantic coast of Morocco are now in the planning stage. The Costa Rican project is intended to reclaim lands badly degraded because of earlier inappropriate agriculture. The proposed Moroccan project involves creating a diverse plant environment where the desert and the sea meet. In this instance, the newly created ecosystems will provide part of the underpinnings for a new human settlement. In all the above examples, the land is not currently fit for intensive agriculture or easy restoration. A new biotechnology, which we have named the desert-farming module, provides the short-term ecological economy needed to initiate the restoration cycle. The development of this technology began at the New Alchemy Institute under my direction in 1974. In summary, a desert-farming module is a
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BioDiversity translucent solar-energy absorbing cylinder with a capacity up to 1,000 gallons (3,785 liters) that is filled with water and seeded with more than a dozen species of algae and a complement of microscopic organisms (Figures 39–1, 39–2, and 39–3). Within these cylinders, phytoplankton-feeding fishes and omnivorous fishes are cultured at very high densities. The species selected depend upon climate, region, and market opportunities: the range of species we have studied is broad, including African tilapia (Tilapia spp.), Chinese carps (Cirrhinus molitorella, Ctenopharyngodan idellus, Hypophthalmichthys molitrix, and Aristichthys nobilis), and North American catfish (Ictalurus spp.) and trout (Saluelinus spp.). Dense populations, up to one actively growing fish per 2 gallons (7.6 liters), produce high levels of waste nutrients beyond the capability of the ecosystem to take up. The module recycles these nutrients in the following ways: nutrients released from the decomposed waste material are absorbed by the fish, the plankton, and the crop plants rafted on the cylinder surface. In addition, partially digested algae that floculate out and settle to the bottom are periodically discharged through a valve to fertilize and irrigate the surrounding ecosystem under restoration. The root systems of the vegetable crop plants take up the nutrients before they reach toxic levels and also capture detritus; they function as living filters by purifying the water. These modules can yield more than 250 pounds (113.5 kilograms) of fish annually in a 25-square-foot (2.3-square-meter) area, depending on species and supplemental feeding rates. At the same time, each unit can produce 18 heads of lettuce weekly, i.e., more than 900 heads per year (Zweig, 1986). Tomatoes and cucumber crops FIGURE 39–1 Solar aquaculture ponds. A dense population of fishes can be seen in the module in the foreground. Photo by J.Todd.
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BioDiversity FIGURE 39–2 Solar aquaculture ponds in winter conditions on Cape Cod, Massachusetts. Photo by J.Todd. can also be grown on the surface for even higher economic yields. An additional benefit of the modules is conservation of water. Since evaporation is almost eliminated from the surface, rates of water replenishment are based on plant evapotranspiration and the amount of water released from the module to irrigate and fertilize the adjacent area (Figures 39–3 and 39–4). Desert-farming modules are an agroecology that require initial seed capital to construct and establish. But to a large extent, tillage, harvesting, fertilizing, and irrigation are a substitute for the heavy equipment that would otherwise have to be used for establishing and operating a farm on degraded soils. Not only are the
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BioDiversity FIGURE 39–3 Desert-farming module in solar greenhouse with lettuce growing hydroponically on surface. Photo by R.Zweig. modules less costly than the equipment, but it may well turn out that they are much more likely to support the restoration process technically and economically. Within a given land restoration project, the modules could be established in rows in the most highly degraded areas. Young trees on the shaded side of these cylinders could be planted and subsequently nurtured by the periodic release of water and nutrients. On the sunny side of the modules, a variety of short-term economic crops could be established to add to the produce from the module. The labor needs for the module-based agriculture could also be used to tend the emerging ecosystems. The approach based on the desert-farming module need not be static in the sense that the modules, having fed and watered the newly emergent vegetation including trees through their most vulnerable stages, could be shifted to new locations to repeat the process. In this way, the short-cycle biotechnology could spread its benefits to surrounding ecosystems over a larger geographic area. For arid environments, such as the Moroccan coast, we have developed a bioshelter system to assist with diversifying an area ecologically. The bioshelter is a transparent climatic envelope or greenhouse structure that houses the fish and vegetable modules. Our prototype is a circular geodesic structure that functions as a solar still and as an incubator for the early stages of the ecological diversification process (Figure 39–5). These bioshelters can even operate where there is no fresh water. In this extreme case, the aquaculture modules are placed inside the climatic envelope and water from the sea is pumped through them. During the day, the
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BioDiversity FIGURE 39–4 A recirculating fish culture system combined with hydroponic cultivation of vegetables. From Baum, 1981.
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BioDiversity FIGURE 39–5 Prototype bioshelter. A geodesic dome housing fish and vegetable modules. Photo by J.Todd. structure heats up until the temperature differential between the seawater in the tanks and the air is great enough to cause the tanks to sweat fresh water, which irrigates the ground around them. Tree seedlings are then planted in this moist zone. Drought-tolerant trees can also be established around the outer periphery of the structure. At night, the moisture-laden air cools to the desert sky, causing water droplets to form on the interior skin of the climatic envelope. With the prototype shelter, we found that drumming on the structure’s membrane in the early morning caused the droplets to fall like rain inside, thereby making it possible to plant the entire interior of the module. Inside the tanks, marine fish and crustacea such as mullet and shrimp can be cultured to form the basis of an economy. After a few years, the original cluster of climatic envelopes can be moved to a new location to repeat the cycle, leaving an established, semiarid agroecosystem behind. These are two examples drawn from a range of biotechnological options that could help reverse environmental degradation and restore diversity and bounty to a region. These advanced technologies may well prove to be essential tools in creating sustainable environments. In all of this, there is of course the fundamental question of land tenureship and social constraints that will ultimately drive any ecological changes. One option for countries with private land holdings and a willingness to tackle serious long-range environmental issues might be the creation of restoration corporations. In this particular model, a corporation would have the financial capability of buying large blocks of ruined land and to hire and train local farmworkers to operate the desert-farming modules, process the foods and other by-products, and tend the
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BioDiversity emerging ecosystems. When the ecosystems are ready for agriculture, natural resource management, and conservation on a given section of land, the corporation could divest itself of the land, selling it to the formerly landless workers who would be trained land stewards and farmers. The original corporation would become a mortgage banking company for the new landholders and at the same time continue to own and operate part of the infrastructure, including the training component, and to share in processing and marketing. Its earnings would be used in turn to acquire new blocks of land and repeat the cycle. In this particular model, there is the potential theoretically to link capital, institutional structures, information, and family-held productive lands to effect land restoration. There is also an opportunity to set aside lands as wilderness, since the intensive agriculture will reduce pressure on the overall environment. Even in poorer parts of the world, there is the chance to generate enough wealth to underwrite continuing ecological research out of which new models of Earth stewardship will arise. REFERENCES Baum, C.M. 1981. Gardening in fertile waters. New Alchemy Q. Summer (5):3–8. Todd, J. 1983. Planetary healing. Annals of Earth Stewardship 1(1):7–9. Todd, J. 1984. The practise of stewardship. Pp. 152–159 in W.Jackson, W.Berry, and B.Coleman, eds. Meeting the Expectations of the Land. North Point Press, San Francisco. Todd, N., and J.Todd. 1984. Bioshelters, Ocean Arks, City Farming: Ecology as the Basis for Design. Sierra Club Books, San Francisco. 210 pp. Zweig, R. 1986. An integrated fish culture hydroponic vegetable production system. Aquaculture 12(3):34–40.
Representative terms from entire chapter: