Biodiversity (1988) / Chapter Skim
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Part 8: Restoration Ecology: Can We Recover Lost Ground?
Part 8: Restoration Ecology: Can We Recover Lost Ground?
Pages 309-352
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From page 310... ...
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From page 311... ...
C H A P T E R 35 ECOLOGICAL RESTORATION Reflections on a Half-Century of Experience at the University of Wisconsin-Madison Arboretum WILLIAM R JORDAN III Editor, Restoration &9 Management Notes, The University of Wisconsin'Madison Arboretum, Madison, Wisconsin to far, in this volume and in thinking ancI discussions about the conservation of biological diversity generally, the emphasis has been on preservation of what we already have.
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From page 312... ...
the Arboretum's collection of restored and partially restored communities is now the oldest an(1 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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From page 313... ...
, has resulted in the development of these species into peculiar, dense patches (Woods, 19841. A related problem with restored communities generally is their small size, which can directly influence their ecological quality.
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From page 314... ...
, were extremely abundant in Resettlement 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.
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From page 315... ...
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.
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From page 316... ...
In press. Ecological restoration as a strategy for conserving biological diversity.
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From page 317... ...
coastline, development has reduced the area of coastal wetlands and endangered certain wetland-dependent species. Despite the threats to biocliversity, 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.
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From page 318... ...
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.
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From page 319... ...
of restored wetland (California State Coastal Conservancy, 19841. Mitigation plans are not final, but the draft concept includes cutting an ocean inlet to serve a new marina.
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From page 320... ...
The population of endangered light-footed clapper rails dropped from about 40 pairs to O and did not fully recover after tidal flushing was restored (16 pairs were present in 19871. In addition, there were major declines of three salt-marsh plant species-corUgrass (Spartina foliosa)
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From page 321... ...
Projects That Replace Functional Wetland Habitat with Modified Wetland Habitat Some restoration projects retain acreage but exchange one type of habitat for another. In these cases, functional wetland habitats may be destroyed in order to create some other habitat type.
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From page 322... ...
A main concern is that existing wetland habitat will be lost and that the artificially created replacements cannot guarantee maintenance of biodiversity. At Upper Newport Bay, a sediment control plan within a California State Ecological Reserve has received wide political support, in part because dredging in the upper bay reduces sedimentation in the lower bay s marina.
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island in south San Diego Bay, which was planned for salt marsh and fish habitat.
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Environmental Protection Agency in their research plan for the nation s wetlands (Zedler and Kentula, 1985~. Ecosystem-level experiments have not been incorporated into wetland restoration projects.
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Only as our understanding of factors controlling wetland ecosystems improves can we ensure the restoration and maintenance of biodiversity. ACKNOWLEDGMENTS Research on wetland restoration was funded in part by NOAA, National Sea Grant College Program, Department of Commerce, under grant number NA80AA' D-00120, project number R/CZ-51, through the California Sea Grant College Program, and in part by the California State Resources Agency.
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From page 326... ...
Winds causing forest treefalls and forest fires have probably been the most important natural disturbances during Amazon forest history. Several studies have shown that treefall disturbances are common in Amazon forests.
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From page 327... ...
The ability of some rain forest species to survive fire disturbances, e.g., when seeds are buried and thus protected and later sprout, may be the result of natural selection (i.e., fire may have been a selecting agent for these characteristics)
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From page 328... ...
A ROLE FOR RESTORATION ECOLOGY Regeneration to forest occurs naturally in Amazonia following natural disturbances and small-scale human-induced disturbances, but where disturbances are severe, human intervention may be necessary to ensure reforestation. Restoration efforts are most needed on abandoned mine sites and highly degraded pastures.
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From page 329... ...
This research sets the stage for our central research goal: to determine how biological and physical forces act to retard the establishment of rain forest tree species in highly degraded Amazon pastures. Our data suggest that forest trees have difficulty establishing in degraded pastures because of three factors: few seeds of forest trees are being dispersed into pasture environments; most seeds that do arrive are killed by seed predators; and ~ the few seeds that do manage to germinate eventually die because of harsh environmental conditions.
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From page 330... ...
All these findings suggest that seed predation is an important impediment to forest regeneration in degraded pastures. Harsh Environmental Conditions in Pastures Harsh environmental conditions present a final impediment to the establishment of forest trees in degraded pastures.
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From page 331... ...
For example, in the pasture study site, vapor pressure deficits are much higher than in the forest and soil water potentials are below the permanent wilting point during the dry season due to the abundance of shallow rooted plants, low soil infiltration rate, and higher evaporative demand of the atmosphere. SEEDS PRODUCED IN FOREST I DISPERSAL 1 GERMINATION ESTABLISHMENT ADULT PLANT / / / / FIGURE 37-1 A summary of the factors that limit the establishment of forest trees in degraded pastures in the Eastern Amazon, Paragominas, Para.
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From page 332... ...
with a knowledge of tree morphology and physiology, tree species can be selected for introduction into degraded pastures based on characteristics such as degree of tap rooting, ability to penetrate compacted soil horizons, drought tolerance, ant] competitive ability.
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From page 333... ...
Ideally, all ecosystems should be restored to their original condition; however, this is often difficult or impossible for the following reasons: detailed ecological information about the original condition is not available, techniques for recolonizing the damaged ecosystem with original species are not adequate, and there is no satisfactory source of organisms for recolonizing to the original condition. Under these circumstances, one might reasonably consider alternative ecosystems that would be ecologically superior to the damaged condition but often markedly different ecologically from the original system (Cairns, 1980, 1985~.
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From page 334... ...
EVIDENCE FOR CAUTIOUS OPTIMISM In view of the present modest capability to predict ecosystem development following remedial measures to repair anthropogenic stress, it may seem arrogant to propose rehabilitation to increase diversity. However, it is abundantly clear that we must both arrest and repair widespread ecological damage.
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From page 335... ...
Many biologists are unaware that some of the worlcl's leading biological field stations are located on sites that sufferer! severe ecological damage less than 100 years ago.
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From page 336... ...
It occurred to me to learn whether the field stations where Drummond and Noble worked were situated on formerly damaged ecosystems. The Mountain Research Station area was logged and burned around the rum of the century, ant!
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From page 337... ...
~ Simple management practices, such as benign neglect, often result in a vastly improved condition. · Good ecological research can be conducted on formerly damaged ecosystems, indicating that the processes in them are ecologically interesting and comparable in many respects to those in undisturbed ecosystems.
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From page 338... ...
The GNP has three functions: · to use existing dry forest fragments as seed sources to restore about 700 square kilometers of topographically diverse land to a dry forest sufficiently large and diverse to maintain into perpetuity all animal and plant species and their habitats known to have occupied the site originally; · to restore and maintain a tropical wildland so that it can provide material goods such as plant and animal gene banks and stocking material; and o to use a tropical wildland as the stimulus and factual base for a reawakening of the intellectual and cultural offerings of the natural world to audiences with a local, national, and international philosophy that is user-friendly. ialpha: diversity measurements are those applied to samples from particular communities (Whittaker, 1972, p.
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From page 339... ...
A few restoration efforts of this magnitude may be more cost-effective in increasing diversity than many smaller projects. INTEGRATED RESOURCE MANAGEMENT On July 8, 1986, I took my class on stressed ecosystems from RMBL to the Mexican Cut tract approximately 10 kilometers away.
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From page 340... ...
Development of an artificial assemblage of plant species that would not exceed a particular height would obviate the use of sprays or cutting and, if carefully struc' tured, would be less of an ecological barrier than the present system. Hazardous Waste Site Closure There are a large number of hazardous waste sites in the United States where the highest concentrations of chemicals can be removed and transformed but where, for a variety of reasons (e.g., Novak et al., 1984, state that "acid leachate will continue to be emitted from this area for some years in the future")
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PROSPECTS FOR RESTORATION ECOLOGY Damaged ecosystems can be changed from ecological liabilities to assets that are useful in both increasing diversity and protecting natural systems in a variety of ways. They can be developed as ecological buffers between waste-treatment systems and natural systems.
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1982. The role of field stations in the preservation of biological diversity.
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From page 343... ...
jetL 1985. Evaluatk~n of an acidic waste site cleanup emu.
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From page 344... ...
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.
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From page 345... ...
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.
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From page 346... ...
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.
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From page 347... ...
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 ( 1 13.
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From page 348... ...
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.
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From page 349... ...
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.
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From page 350... ...
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From page 351... ...
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.
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From page 352... ...
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.
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