Extreme events, such as drought, are predicted to become more intense and frequent as climate change progresses. Areas such as the central US and Great Plains are particularly vulnerable due to a predicted drying of the entire region, leading to losses in soil moisture and water available for plant production. This could have detrimental impacts both on the native flora and fauna of these regions and economically in rangeland areas. Scientific research shows that the soil microbiome (bacteria and fungi) could be negatively impacted by this decrease in water availability. Since the soil microbiome is vital to plant growth, studying the effect of drought on both plants and the microbiome will give a clearer picture of the impact drought has and allow us to better mitigate any detrimental impacts. This project specifically aims to understand how the microbiome responds post-drought to gain insight on microbiome resiliency. Our experiment imposed a four-year long drought in a large-scale field experiment, and measured recovery in microbial function and structure one year (of three) after the end of an experimental drought at Konza Prairie (tall grass prairie) long term ecological research station (LTER) in northeastern Kansas.
Results/Conclusions
The first year of recovery post drought showed decreases in soil carbon, soil respiration and microbial respiration with an accompanying increase in carbon cleaving soil enzyme activity. This would suggest a decrease in microbial activity. Further, we found that inorganic nitrogen pools and nitrogen mineralization were consistently higher across the entire growing season. This increase in inorganic nitrogen pools could be due to a decrease in plant or microbial nitrogen uptake, but nitrogen microbial biomass was unchanged from the control. Therefore, plant uptake of nitrogen was likely decreased during drought leading to the higher levels of inorganic nitrogen in the soil (plant data is currently being processed). Carbon microbial biomass and carbon mineralization were also unchanged from the control. This further indicates that there is a potential decrease in microbial activity (not biomass) and decrease in plant uptake of nitrogen one-year post cessation of a drought. We are awaiting sequencing data (bacterial and fungal), which will tell us if there were any structural shifts that could have led to the functional changes noted above. Two subsequent years of recovery measurements will allow us to understand the rates of recovery of these processes post drought or whether they recover within that timeframe.