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Issues and Challenges of Farmland Habitat Conservation
Farming Threatens Habitat
Agricultural expansion in the lower 48 states has been the leading cause of habitat loss and fragmentation, which in turn remains the primary threat to imperiled and federally listed species (Stein, Kutner, and Adams, 2000). This ranks farming and ranching as an even greater threat to biodiversity loss than commercial development, pollution from manufacturing, logging, energy exploration, and other activities (Bruce A. Stein, et. al., Precious Heritage: The Status of Biodiversity in the United States, Oxford University Press, 2000). As a result, there is a direct correlation between our grocery lists and the endangered species list.
Agriculture's most significant impacts concern water and aquatic systems. Water is the life force of all living organisms on the planet, yet nearly 70 percent of the world's fresh water is consumed by agriculture. The natural flow of rivers and streams is being interrupted or depleted and leaves many habitats high and dry. Lakes are shrinking due to diversions, wetlands are drained, tilled, and replumbed, and aquifers are pumped exponentially faster than they can be replenished by annual rainfall.
Consider some of the following statistics:
- While U.S. farmers rely on groundwater for 40 to 45 percent of the irrigation requirements, irrigation techniques are only 50 percent efficient.
- 60 percent of the rivers in the United States have been impaired due to agricultural runoff.
- Manure from animal confinement facilities exceeds the volume of human sewage waste by 130 times, and much of this waste reaches waterways and groundwater untreated.
- The flow of nitrogen and phosphorous fertilizers, pesticides, and other agricultural runoff from the midwestern corn belt into the Mississippi River has created an 8,500 square-mile hypoxic "dead zone" in the Gulf of Mexico, causing fish kills, degradation of coral reefs, and the near collapse of the fishery. This is just one of a number of dead zones that have been identified around the continent.
As far back as the late 1930s, Aldo Leopold identified the ideal type of agriculture as "biotic farming." "A good farm," wrote Leopold, "must be one where the wild flora and fauna has lost acreage without losing its existence." (Aldo Leopold, "A Biotic View of the Land," from The River of the Mother of God and Other Essays, The University of Wisconsin Press, 1991.) Following Leopold's land ethic, agriculture would take place within a matrix of different habitat types in any given ecoregion. This would require conducting ecological assessments within a given area to determine what habitat types have been disproportionately affected. Optimal goals would be set to provide at least 30 percent of undisturbed habitat type throughout the ecoregion by preventing the conversion of any intact habitat for production and restoring already disturbed areas.
Integrating large blocks of riparian and associated upland habitats can help facilitate the movement of many species, particularly top predators that play a key role in regulating an ecosystem's predator and prey population dynamics. Similarly, the transcontinental journeys of migratory birds, insect pollinators, and other species can be aided by the presence of on-farm wetlands and other blocks of habitat that function as critical "stepping stones."
Grassland-dependent birds
Grassland-dependent birds are among other victims of habitat conversion to massive-scale, industrial agriculture and development. The western meadowlark, for example, was one of Wisconsin's more common birds in the 1960s. Since then, its numbers have declined by over 90 percent (Wisconsin Breeding Bird Survey, 1966-1999). This fate has befallen many of Wisconsin's-and the nation's-grassland-dependent species, such as the vesper sparrow (70 percent decline) and the bobolink (50 percent decline). Other grassland flora and fauna, from plants and insects to reptiles and amphibians, have also experienced significant losses.
There is a direct correlation between our grocery lists and the endangered species list.
Practices such as pasture-based meat production, diversified land use, habitat buffers along river systems, and protecting critical natural areas on farms and ranches help to establish a sense of fluidity or permeability on the agricultural landscape.
Conservation-based agriculture must take place on a landscape scale, and optimizing conservation values on individual properties is essential.
Criteria that define biodiversity protection on organic farms and ranches, and potential benefits and challenges to landowners.
