Ant biodiversity and ecosystem services in bioenergy landscapes

Abstract

Most strategies for limiting global climate change invoke the use of bioenergy, but biofuel crops vary in climate mitigation potential and in the provision of other ecosystem services. The predominant biofuel in North America is ethanol produced from corn Zea mays. Corn is grown on ∼360,000 km2 of land in the U.S. and ∼40 % of the yield is used for ethanol production. Despite its prevalence, corn ethanol is a poor climate change mitigator and the spread of intensive corn agriculture also leads to the loss of biodiversity and an unknown complement of associated ecosystem services. To test for effects of land use intensity on the provision of ecosystem services from biofuel crops, we compared insect communities inhabiting long-term experiments in which land use intensity varied from annual corn production to less intensive native perennial biofuel crops (switchgrass and restored prairie) and unmanaged native forests. Within the experiments we focused on ants (Formicidae: Hymenoptera), including their diversity, abundance, functional traits, and predation of biofuel crop pests. Native perennial biofuel crops supported up to 185 % more ant species than corn fields and provided up to 55 % more natural pest suppression. They also contained higher functional richness by supporting social parasites and seed dispersing ants that were absent in corn. Biofuel crops did not differ in ant activity or the prevalence of introduced ants. Our results highlight tradeoffs in bioenergy production and suggest ways to maximize benefits for wildlife and people. Converting some corn fields to prairie or other native vegetation could restore landscapes while mitigating climate change and meeting energy needs.