Functional diversity promotes multifunctional cover cropping systems

Jason Kaye
Department of Ecosystem Science and Management Penn State University

Presented at the All Scientist Meeting (2015-04-15 to 2015-04-16 )

Increasing ecosystem service provision is an emerging goal of contemporary agriculture. Exploiting biodiversity to meet this goal is a promising approach, though relationships between diversity and ecosystem services remain largely unexplored for innovative practices such as cover crop polycultures. In this study, we sought to answer two questions: (1) Does increasing species richness lead to greater ecosystem service provision by cover crops? (2) Beyond richness, are there other components of cover crop diversity that influence the simultaneous provision of multiple services (multifunctionality)? To answer these questions, we carried out a two year study of seventeen cover crop systems ranging in diversity from one to eight species. In each system we measured five ecosystem services: weed suppression, nitrogen (N) retention, N provision, N supply, and subsequent corn crop yield. We identified a positive relationship between species richness and multifunctionality (p=0.01, R2=0.05). Increasing functional diversity and taxonomic evenness also led to increased multifunctionality. A quadratic relationship between multifunctionality and one metric of functional diversity, functional specialization, explained the greatest proportion of variability (p<0.01, R2=0.41) and indicated that cover crop stand evenness and inclusion of species with complementary N acquisition strategies maximized multifunctionality. We have shown that although increasing species richness can increase ecosystem service provision, using cover crop diversity to create multifunctional agroecosystems requires polycultures that incorporate functional diversity. These analyses are the first of their kind to examine the relationship between cover crop diversity and ecosystem services derived from agriculture.

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