Submitted to: US-International Association for Landscape Ecology
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 2005
Publication Date: March 16, 2005
Citation: Goslee, S.C., Gonet, J.M., Sanderson, M.A. 2005. Landscape diversity in agricultural systems[abstract]. US-International Association for Landscape Ecology. p. 81. Interpretive Summary: An interpretive summary is not required.
Technical Abstract: When studying landscape structure in the eastern United States, ecologists have often treated agricultural areas as one homogeneous type. There can be considerable diversity in vegetation structure, composition and management within a single farm or across an agricultural landscape. Typical uses in northeastern grazing areas include: row crops, permanent pasture, woodlot, fencerow, streambank buffer and holding areas. Even within one use class there can be very different plant species compositions, contributing to beta diversity on a farm. The spatial layout of different land uses in relationship to the topography of the site, to permanent structures, and to watercourses (e. g. streamside buffers) may strongly impact the economics of the farm, its conservation potential and its effect on surrounding ecosystems, but baseline information about beta and landscape diversity in agricultural systems is rare for the northeastern United States. A seven-year regional survey of alpha diversity in grazing lands provided the background for a new study of beta and landscape diversity. An intensive survey of five grazing operations in New York, Pennsylvania and Maryland was begun in spring 2004. The vegetation of all pastures on each farm were sampled along a transect three times during the growing season. Five to seven pastures were selected for more intensive sampling using the modified Whittaker plot method. Soil samples were taken from each pasture, and standard agronomic tests applied. Digital elevation models, aerial photographs and on-farm mapping were used to characterize the topography and land use within and surrounding each farm. Each producer was interviewed to learn the land use and management history of different areas within the farm. On-farm sampling to date has only included grazed areas, but will expand to include all vegetation types present on each farm, and will continue for two more years. We found that despite the common goal of animal production shared by all the farms in this study, there is a wide range in both spatial structure and beta diversity. Management units, delineated by permanent fences, were an average of 3.6 ha, but ranged from 0.3 to 52 ha. The average size of management unit varied by farm, with a mean size of 1.4 ha on a Maryland farm and 16 ha on a New York farm. Total grazing area on a farm ranged from 25 to 240 ha. Areas managed for grazing are often smaller and more irregularly shaped than areas managed for row crops. Although there are less than ten dominant species in the grazing areas of any farm sampled, we found up to 57 species in one 1000 m2 area, and up to 107 species on a farm. Agricultural areas contribute to the landscape diversity of the northeastern United States by adding open herbaceous patches to the largely forested surrounding regions, and all agricultural uses are not the same. Although the dominants are largely naturalized forage species, pastures, in contrast to croplands, can have high alpha and beta plant diversities, and provide habitat for species that require open areas.