COS 104-2 - Soil bacterial community responses to multiple climate stressors in an early successional plant community

Abstract: Anthropogenic climate warming is predicted to increase the planet’s average surface temperature by up to 3°C by 2100. In addition to warming temperatures, precipitation regimes are also shifting in their frequency and severity, and are predicted to become more extreme, causing heavier rainfall events and more frequent and severe droughts. These climate changes can cause ecological communities to alter their structure and function and these alterations have been well documented in aboveground communities. However, what is less understood is how belowground microbial communities respond to various climate stressors. Soil microbes are responsible for belowground carbon and nutrient cycling, thus playing a central role in ecosystem processes. Therefore, understanding how soil microbes respond to climate change is crucial to our ability to predict ecosystem processes in a changing world. Additionally, studies looking at the effects of multiple climate stressors occurring simultaneously on soil microbes are lacking. To address these knowledge gaps, we used an integrative approach that combines field experimentation with metagenomic amplicon sequencing to quantify how multiple climate change stressors affect soil microbes.

Here we ran a fully factorial experiment at Kellogg Biological Station’s Long Term Ecological Research site with the following treatments across 6 replicate plots: open-top chambers to mimic year-round warming; rainout shelters to mimic a 6-week drought; and insecticide to reduce insect herbivory. Soil samples were taken in summer 2021 at four different times: pre-drought, peak-drought, post-drought, and recovery. In order to characterize the soil bacterial community structure across samples, DNA was extracted to sequence 16S V4 gene amplicons. Soil moisture was also measured at peak and post-drought.

Preliminary results reveal that soil moisture responded strongly to the 6-week drought; peak-drought soil moisture was lower compared to post-drought. Despite this, there were no strong differences in soil microbial community composition among treatments or time of sampling. This multi-year study began in 2021 and will continue through 2023 to further elucidate the short and longer-term responses of microbes to warming and drought. This research will ultimately advance the understanding and prediction of soil microbial community responses to multiple climate stressors over time while accounting for multi-year legacy effects of drought, warming, and reduced herbivory.