Kemmerling, L. R. 2022. Diversifying agricultural landscapes for biodiversity and ecosystem services. Dissertation, Michigan State University, East Lansing MI.
This dissertation focuses on strategies to restore biodiversity and ecosystem services in agricultural landscapes through diversifying the plant community at the landscape level. Biodiversity and ecosystem services are declining globally, and a leading cause of this decline is large-scale row crop agriculture which results in habitat loss and pollution. Simultaneously, the human population is growing, as are human demands for resources produced by agriculture. Diversifying agricultural landscapes is one method to both mitigate the loss biodiversity while providing essential human resources. I conducted three studies that test if diversifying cropping systems can increase biodiversity and ecosystem services and maintain or even increase agricultural yield. In Chapter 1, I tested the ability of multiple native, perennial bioenergy crops (alternatives to annual bioenergy crops) to provide both crop yield and conserve pollinators. I measured pollinator abundance and species richness, flower abundance and species richness, and crop yield across four native perennial biofuel crop varieties: successional land (unmanaged), restored prairie, a mix of native grasses, and seeded switchgrass. Successional land had the most diverse community of pollinators but the lowest crop yield, native grasses had the highest yield but the least diverse pollinator community, and switchgrass and restored prairie were intermediate. If both pollinator conservation and crop yield are valued similarly, restored prairie was the optimal biofuel crop. Chapter 2 tested the effects of crop management practices in row crop agriculture, including the establishment of a conservation practice called “prairie strips” on biodiversity and ecosystem services. Prairie strips are strips of farmland retired from production and actively restored with native prairie plant species. I synthesized the tradeoffs and synergies of a suite of biodiversity and ecosystem service measures across a land use intensity gradient, as well as their spillover from prairie strips into cropland. The lowest land use intensity consistently had the highest levels of biodiversity and ecosystem services other than crop yield. Treatments with prairie strips had higher pollination services and a higher abundance of butterflies and spiders than other row crop treatments. Crop yield in a treatment with low land use intensity and prairie strips remained as highest land use intensity treatment, even when including the area taken out of production for prairie strips. Biodiversity and ecosystem services decreased with increasing distance from prairie strips and this effect was more pronounced in the second year of the prairie strips than the first for several measures. These results show that, even in early establishment, prairie strips can contribute to the conservation of biodiversity and ecosystem services without a disproportionate loss of crop yield. Chapter 3 further investigated one of the measures addressed in Chapter 2: butterfly biodiversity. I measured butterfly and plant species richness and abundance across three years in the same land use intensity gradient. Butterfly abundance and richness increased as land use intensity decreased. Prairie strips harbored unique butterfly communities and had a higher abundance of butterflies than other row crop treatments, including conservation land. Across the 1 ha plot of which 5% was prairie strip, butterfly abundance was higher in row crops with prairie strips than in row crops without prairie strips, likely as a result of prairie strips and other crop management practices in treatments with prairie strips, such as reduced pesticides. Altogether, this work presents evidence that restoring habitat within farms can support biodiversity and ecosystem services without disproportionately impacting crop yields. Furthermore, when strategically placed, these conservation strategies can prevent unnecessary greenhouse gas emissions, and potentially increase crop yield.
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