Understanding the biogeochemical role of soil microbial communities in Northern VT agricultural riparian zones connected to Lake Champlain waterways

Riparian buffers are integral to managing nutrient flows and fluxes across water systems. They are especially important in controlling nutrient cycling during extreme weather events, which are predicted to increase with climate change. One consequence of extreme events is increased eutrophication and algal blooms which have negatively affected the health of Lake Champlain in recent years. Soils are an important component of riparian buffers and their role in biogeochemical cycling during extreme events is not fully understood. Specifically, the influence of soil microbial communities on nutrient flows and fluxes has not been thoroughly studied. We investigated the response of riparian buffer soil microbes under average and extreme rainfall conditions with a soil incubation study. We collected intact soil cores from wetland and dry locations within a riparian zone of Hungerford Brook in Swanton, VT, in order to compare how soils with different soil moisture regimes respond to extreme events. We simulated slow and fast rainfall conditions and measured the responses of the soils over seven days. Slow wetting was based on average rainfall rates in Swanton, VT while fast wetting was based on the heaviest rainfall period Swanton experienced during Hurricane Irene in 2013. We measured microbial biomass and extracellular enzymatic activity to assess how microbial populations are affected by the treatments. To better understand how microbial responses impact nutrient fluxes, we analyzed greenhouse gas fluxes using a photo-acoustic gas analyzer and we collected leachate for nitrate and ammonium analysis. Our data provides novel insights on the complexities of the characteristics of an agricultural riparian zone in Northern Vermont to better inform the VT-EPSCoR Integrated Assessment Model.