Restoration Ecology
Ecological restoration is an attempt to reset the ecological clock and return a damaged ecosystem to its predisturbance state—to turn a disused farm into a prairie or to convert a parcel of low-lying acreage into a vigorous wetland. Precise replication of the predisturbance condition is unlikely to occur because each ecosystem is the result of a sequence of climatic and biological events unrepeatable in precisely the same order and intensity as the original sequence. However, close approximations of the predisturbance condition are often possible, with differences from the original apparent only to professionals.
Within this limitation, restorationists strive to re-build ecosystems that, if not exactly like their original predecessors, possess the qualities of a healthy ecosystem. These properties include:
- dominance of indigenous (native) species
- sustainability or the ability to perpetuate
- resistance to invasion by non-native or pest species
- the presence of healthy functions such as photosynthesis, respiration, and plant and animal reproduction.
- the ability to generate nutrients such as nitrogen and store them in the ecosystem
- a pattern of interaction between key species similar to the pattern found in undisturbed ecosystems, including relationships in the food chain
Regrettably, the term restoration as used in the media and by organizations responsible for ecological damage often refers to cosmetic activity—the clean up of oil, for instance, with the expectation that once a substantial amount of spilled oil has been removed, natural processes will restore the ecosystem to its former condition. Merely re-creating the form of an ecosystem without attention to whether it is functioning is not considered to be true ecological restoration. Developers also abused the term restoration when acquiring land for malls or residences in exchange for creating equivalent or larger wetlands elsewhere. Insead of functioning restorations, they often carry out substandard cosmetic restoration efforts.
Restoration ecology developed in the twentieth century as a response to habitat destruction brought about by industrialization, overpopulation, and agricultural mismanagement. Pioneering biologists, such as Aldo Leopold, began to advocate an approach to healing damaged ecosystems that involved direct human intervention.
Moreover, restoration ecology is more than just applied science that uses the insights of ecology to build ecosystems. It is becoming an essential research tool to test the accuracy of ecological theories through direct experience. For example, the role of fire in the maintenance of prairie ecosystems has come to be better understood through its application on restored tracts that were failing to thrive.
As habitat loss accelerates, restoration takes on increasing importance as means of preserving habitat for threatened species, rekindling lost biodiversity, restoring mineral balance to eroded and infertile lands, improving water quality, and preserving atmospheric gas balance. The task of restoration, seen as rather abstract in years past, is now viewed more concretely as the consequences of destruction of habitat begin to be understood.
Although the specific stages of a restoration project depend on the initial state of the land and the desired end, a typical restoration project begins with certain steps to create the conditions necessary for natural processes to gain a foothold. On eroded and compacted soils the first step is often to physically loosen the damaged soil by tearing or furrowing. This promotes water retention and creates suitable microenvironments for plant seeds. On depleted land, it also might be necessary to add fertilizer or organic mulch to provide initial replenishment of nutrients such as nitrogen and phosphorus.
Suitable plant seeds, preferably from indigenous species, are then introduced. These are usually key varieties called matrix species. Nurse species that create the conditions needed to hasten growth of other plants (a process called facilitation) may be introduced. Sometimes a sequence of species must be introduced in a specific order. For example, on clay mining wastes, the best growth is obtained by planting annual grasses and legumes, then perennial grasses a year later.
Often animal colonization is left to nature, especially if the site under restoration is near other predisturbance sites. Management of the site to monitor its progress and to remove unwanted invading species is usually carried out in succeeding months and years. If a restoration effort is successful, the site gradually returns to its natural state and the need for further intervention decreases.
Ecological restoration requires contributions from a large number of academic disciplines, although the precise mixture will vary from one restoration project to another. The term restoration ecology is misleading in suggesting that the activity is for ecologists only. All restoration projects require some degree of funding, and large-scale projects, such as surface mine reclamation or restoration of a wetland, river, or lake, may require substantial multi-year funding. In addition, if the restored ecosystem is to be protected from further damage, public understanding and support are necessary. As a consequence, disciplines that study the values of society and identify those that align with ecological values are extremely important for large-scale, long-term successful restoration efforts.
Equally important is the knowledge obtained from climatologists, chemists, engineers (where restructuring is necessary), hydrologists, geologists, statisticians, forestry and wildlife specialists, geneticists, soils and sediment chemists, political scientists, attorneys, and a variety of other professions. Historians and anthropologists often have a crucial role in restoration because the history of ecological damage may be reconstructed with historic evidence, both written and through cultural and biological artifacts and relics.
The role of private citizens in a restoration effort often is pivotal. Community leaders may provide funds toward carrying out restoration, while the work of local volunteers helps to connect the community with the organizations and institutions administering a project. Community involvement also provides a project with a long-term focus months or years after the initial effort is complete. Moreover, the labor-intensive task of restoration seems to thrive when it is carried out by volunteers and concerned individuals working together with specialists.
Although underlying theory in the field of restoration ecology is still in its infancy and the precise outcome of a project is almost always uncertain, restoration efforts virtually all result in improvement to damaged environments. The condition of a restored system may be strikingly superior to the damaged condition. For example, the tidal Thames River in England had virtually no fish species in the 1950s. However, many years after pollution clean up and restoration, over 100 species were found in the tidal area. In the United States, Lake Washington in the Pacific Northwest, the Kissimmee River in Florida, the Rio Blanco in Colorado, and the Hackensack River Meadowlands in the New York metropolitan area are examples of successful ecological pollution clean-ups and restoration. Many of these efforts were citizen-initiated.
The United States Department of Agriculture Fish and Wildlife Service (USFWS) has undertaken a new approach to restoring waterways, lakes, and wetlands looking at the processes that impact these ecosystems from a larger watershed perspective. Identifying sources of pollution and environmental stress at the level of the watershed allows scientists to incorporate study of the surrounding land and its effects on habitat destruction in the at risk body of water. An example where watershed analysis sucessfully provided the necessary information for ecological restoration is in the restoration of stream corridors in the Whitefish Mountains of Montana.
Another success story is the restoration of the Lanphere Dunes Unit of the Humboldt Bay National Wildlife Refuge by the Nature Conservancy and its partners. The major challenge in the Lanphere Dunes was eradication of a 10-acre (4-ha) patch of non-native invasive grass called European beachgrass (Ammophila arenaria). European beachgrass is destructive to dunes because it changes that way that sand accumulates. This alters the suitability of the habitat for native plants. The elimination of the non-native grass and restoration of native plant communities was accomplished with more than 2,000 person hours per acre of volunteer labor over the course of three years. As of 1997, native plant cover had increased by almost 50%.
Similar international restorations, such as the Guanacaste dry forest in Costa Rica, show that citizens of developing countries with far fewer monetary resources the United States can also have strong involvement in ecological restoration. In a time of environmental attrition, the restoration movement plays a role in shaping the future by helping citizens develop a feeling of connection between themselves and their wild lands, while providing concrete improvements in ecological conditions.
Resources
Books
Berger, J. J., ed. Environmental Restoration: Science and Strategies for Restoring the Earth. Covelo, CA: Island Press, 1989.
Bradshaw, A. D., and M. J. Chadwick. The Restoration of Land. Berkeley: University of California Press, 1980.
Cairns Jr., J. Rehabilitating Damaged Ecosystems. 2 vols. Boca Raton: CRC Press, 1988.
Ehrlich, P. R., and A. H. Ehrlich. Healing the Planet. New York: Addison-Wesley, 1991.
Jordan III, W. R., et al., eds. Restoration Ecology: A Synthetic Approach to Ecological Research. Cambridge: Cambridge University Press, 1990.
National Research Council. Restoration of Aquatic Ecosystems: Science, Technology, and Public Policy. Washington, DC: National Academy Press, 1991.
Periodicals
Burke, William K. "Return of the Native: The Art and Science of Environmental Restoration." E Magazine, July/August 1992.
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