Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/8/2010
Publication Date: 8/19/2010
Citation: Steenwerth, K.L., Smukler, S.M., Jackson, L.E., Sanchez Moreno, S., Fonte, S.J., H.Ferris, H., Klonsky, K., O'Green, A.T., Scow, K.M. 2010. Biodiversity and multiple ecosystem functions in an organic farmscape. Agriculture, Ecosystems and Environment. 139:80-97. Interpretive Summary: Relatively little is known of the actual environmental outcomes of managing non-production areas on farms for biodiversity, coined ‘farmscaping.’ This study quantifies biodiversity and its associations with ecosystem functions by inventorying communities of plant and soil organisms in the six distinct habitats of an organic farm in California’s Central Valley, and by monitoring multiple ecosystem functions provided by each habitat. Ecosystem functions that were assessed were surface water infiltration rates, greenhouse gas emissions, loss of dissolved organic carbon, and soil nitrate leaching. ‘Farmscaping’ that maximized non-crop habitat resulted in increased non-production ecosystem functions (e.g. water regulation, carbon storage) and biodiversity (particularly plant diversity) that was disproportionally greater than the percent loss in crop production, as compared to monoculture systems.
Technical Abstract: The environmental impact of agricultural production dominated by monocultures may be improved through minor increases in landscape diversity. To increase farmscape diversity farmers in the United States are beginning to manage non-production areas of their farms to create a more diverse set of habitats. Relatively little is known, however, of the actual environmental outcomes of this practice, coined ‘farmscaping.’ To improve the understanding of farmscaping, this study quantifies biodiversity and its associations with ecosystem functions by inventorying communities of plant and soil organisms in the six distinct habitats of an organic farm in California’s Central Valley, and by monitoring multiple ecosystem functions provided by each habitat. Two years of inventories of a riparian corridor, hedgerows, two separate production fields, a system of drainage ditches, and tailwater ponds showed different functional groups and greater native plant diversity in non-cropped areas, but less pronounced differences for belowground organisms. Multivariate statistics indicate associations of nematode functional groups, microbial communities (phospholipid fatty acid analysis) and certain earthworm taxa with particular habitats. Monitoring showed that some habitats were almost entirely responsible for certain ecosystem functions but sometimes at a cost of other functions. Riparian and hedgerow habitats with woody vegetation stored 19% of the farmscape’s total carbon (C), despite their relatively small area (only 6% of the total). Surface water infiltration rates in the riparian corridor were >230% higher than those observed in the production fields, while concentrations of dissolved organic carbon (DOC) collected in soil solution using ceramic cup lysimeters were as much as 65% higher. The tailwater pond reduced mean total suspended solid concentrations in irrigation runoff by 97% but was also a source of higher N2O-N emissions. The drainage ditches however, had the highest losses in terms of both N2O-N emissions (mean values of 16.7 µg m-2 hr-1) and NO3--N leaching (mean values for anion exchange resin bags at 75 cm depth in the second year were 12.1 g m-2). Overall, mean N2O-N emissions were greatest in the irrigation habitats, but overall were very low for all the habitats. To assess the relative tradeoffs between ecosystem functions plot level analyses were extrapolated to the entire farmscape and to various land management that ranged from monoculture production to a scenario that maximized non-cropped habitat. The latter resulted in increased non-production ecosystem functions (e.g. water regulation, carbon storage) and biodiversity (particularly plant diversity) that was disproportionally greater than the percent loss in crop production. This study indicates habitat enhancement through farmscaping will increase both biodiversity and multiple ecosystem functions of agricultural lands.