Publication Date

Spring 2013

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Studies

Advisor

Rachel O'Malley

Keywords

agroecology, biological control, natural enemies, organic farms, sustainable agriculture

Subject Areas

Environmental studies; Environmental science

Abstract

Modern industrial agriculture is the principal cause of anthropogenic land use changes for terrestrial ecosystems. Approximately 40% of the planet's land surface, or half of the habitable area, is now composed of agricultural landscapes. The simplification and industrialization of agriculture are the biggest drivers of global biodiversity loss, especially on Californian's Central Coast. Diversified organic agriculture, however, may offer some refuge for non-crop species. In this study we analyzed insect and plant biodiversity on and adjacent to organic vegetable farms on the Central Coast of California at two spatial scales, the landscape-scale and a smaller within-farm scale. At the landscape-scale, insect data were collected using malaise traps across 35 organic farms in 2005 and 2006, and vegetation diversity was assessed using 0.5 km-radius circular plots. At the smaller farm-scale, insect biodiversity was assessed using 4.5 cm-radius pan traps to collect insects in a single heterogeneous organic farm in 2012, and vegetation was assessed in 1.5 m-radius circular plots. Non-crop vegetation biodiversity was associated with insect biodiversity at both scales, but landscape-scale results showed greater temporal and spatial variation than farm-scale results. Overall, the diverse farm systems enhanced the biological diversity and productivity of the agricultural landscape.

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