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Changing land use in rural America: Consequences for biodiversity.
HANSEN, ANDREW*,1, ARCHER, STEVE2, KNIGHT, RICHARD3, MARZLUFF, JOHN4, 1 Montana State University, Bozeman, MT2 Texas A&M University, College Station, TX3 Colorado State University, Fort Collins, CO4 University of Washington, Seattle, WA
ABSTRACT- Rural lands in the United States have undergone rapid change in land cover and land use in recent decades. Three pervasive trajectories of change are; outgrowth of cities into rural areas (urbanization); immigration into rural areas with high natural amenities (natural-amenity based growth); and abandonment of agricultural lands (ag abandonment). The objective of this talk is to synthesis current knowledge on the consequences of these land use trajectories for biodiversity (landscapes, communities, and species). We will focus on three drivers of biodiversity under these land use trajectories: rural settlement; outdoor recreation; and woody plant encroachment. Under both urbanization and natural-amenities based growth areas in natural cover types are converted to rural residential, suburban, and urban land covers. Natural habitats contract and are increasingly fragmented by roads, cities, and other infrastructure. Natural disturbances such as fire or flooding are excluded and disturbance-driven habitats may become rare. Introduction of exotic species, expansion of generalist native species, and losses of native top predators may alter biotic processes such as predation and competition. Expanding human density and outdoor recreation lead to increasing attraction, displacement, or mortality of native species by humans and pets. Under these trajectories of change, diversity of native species generally drops and top tropic levels are reduced, while exotic species expand. Under all three trajectories of land use change, wood plants may expand into non-woody habitats or open forests may become more dense. Agricultural abandonment sometimes leads to expansion of natural habitats, natural ecological processes, and native species. In other cases, abandoned fields or pastures are succeeding to new vegetation types (e.g., grasslands or shrublands to forests), with novel disturbance regimes and novel patterns of biodiversity. We conclude by drawing implications for research and management.
KEY WORDS: land use, biodiversity, rural settlement, urbanization