Linking plant diversity and land use patterns in agricultural landscapes

Planning successful agricultural conservation or agri-environment schemes requires a landscape scale perspective and an understanding of how biodiversity resources are distributed across landscapes._ To contribute to this goal, we applied a GIS-based approach linking field sampling of plant communities to land use patterns in an intensively farmed region in Pennsylvania, USA._ Agriculture in the region consists mainly of large scale grain-fed dairy operations, and the landscape is characterized by corn, soy, alfalfa, and small grain fields within a matrix of pastures, small woodlots, and early successional grasslands that serve as riparian strips._ We used aerial imagery to stratify four study landscapes into digitized maps of four basic land use classes: arable fields, pastures, grasslands, and woodlots._ We then used a nested plot design to survey plant communities and build species/area curves in a random subsample of four sites of each land use type in each landscape._ We used this data to ask: What are the differences and variation in species richness and species composition across the four land use types? How is plant diversity partitioned within a landscape and within land use types into ?, ?, and ? components? Results indicate consistent differences in species richness and species/area relationships across land use types, but a broad range in community composition for each type._ Most of the species richness within a landscape (?-diversity) was found in the grassland and woodlot habitats (high ? and ?-diversity), but a high level of ?-diversity for each land use type meant that many uncommon plant species also utilized the intensively managed arable field and pasture habitats. We encountered 377 species through sampling a total of only 6.4 ha, demonstrating that this approach is an efficient method for rapidly assessing plant diversity at landscape scales and linking diversity patterns to land use types.