DATE/TIME: Friday, May 7, 2021, 2:30 pm
PLACE:
Brittany Hanrahan
USDA Agricultural Research Service
Exploring controls on ecosystem function and the role of conservation practices in agricultural streams
Over the past 150 years, much of the Midwestern US has been converted from prairies and wetlands to intensive row crop productions of corn and soybeans. The effects of agricultural land use, including riparian vegetation removal, substrate homogenization, and altered hydrologic regimes, manifest as a complex array of physical and chemical changes to stream ecosystems that influence biogeochemical cycling. As a result, agricultural watersheds, also known as "agroecosystems", export excess nitrogen (N) and phosphorus (P), causing numerous water quality problems including drinking water contamination, loss of biodiversity, and eutrophication of downstream freshwaters and coastal zones. In this talk, I will examine the linkages between terrestrial land cover and stream ecosystem function and highlight the role of abiotic controls on ecosystem processes, like nutrient uptake and ecosystem metabolism. I will also demonstrate the influence of conservation practices, including floodplain restoration and watershed-scale land cover change, on nutrient loss from a small, agricultural watershed. Finally, I will discuss the challenges and benefits of quantifying the effects of conservation efforts across spatial and temporal scales.