Agricultural Intensification Across a California Landscape
In an agricultural landscape located in western Yolo County in California’s Central Valley, we sampled along riparian corridors following a gradient of land use intensity from irrigated row crop agriculture in the east to grazed upland grasslands in the west, as shown in the figure above. We used a GIS-based approach to sample in a representative way across the landscape.
Abstract from Culman et al. (2010): "Agricultural intensification has led to dramatic losses in biodiversity over the past several decades. Many studies have shown the effects of intensification on vegetation or soil communities at field or local scales. However, the functional significance of biodiversity may only appear at larger spatial and temporal scales, due to exchanges among local ecosystems throughout a landscape. To examine how patterns of biodiversity loss are reflected at larger spatial scales, plant and soil biodiversity and associated indicators of ecosystem functions were assessed in riparian areas over a 150 km2 agricultural landscape in the Sacramento Valley of California. Publicly-available GIS data were first used to classify and select sites over the range of soils, topography and plant community types. Representative sites from the landscape were sampled for soil physicochemical properties, as well as microbial, nematode, and plant communities. Higher agricultural intensification, based on field and landscape indices, was negatively correlated with richness and diversity of plant and soil taxa, and was related to indicators of ecosystem functions, such as increased soil nitrate and phosphorus loading, decreased riparian health ratings, and lower soil carbon, soil microbial biomass and soil food web structure. Both field- and landscape-scale factors played important roles in the measured losses. The study area was composed of a wide array of soils, vegetation, and land management, indicating that the observed trends transcended site-specific conditions."
Culman, S.W., A. Young-Mathews, A.D. Hollander, H. Ferris, S. Sánchez-Moreno, A.T. O’Geen, and L.E. Jackson. 2010. Biodiversity and soil ecosystem functions over a landscape gradient of agricultural intensification in California. Landscape Ecology 25:1333-1348.
Young-Mathews, A., S.W. Culman, S. Sánchez-Moreno, A.T. O’Geen, H.Ferris, A.D. Hollander, and L.E. Jackson. 2010. Plant-soil biodiversity relationships and nutrient retention in agricultural riparian zones of the Sacramento Valley, California. Agroforestry Systems 80:41–60.