Response of stream fungi on decomposing leaves to experimental drying

Climate change may lead to increased droughts in the future, which in turn may lead to increased periods of stream drying. We conducted an experiment to test the effects of drying on fungal communities and microbial activity on decaying leaves from a stream. Our experimental setup included immersion of maple leaf cores for 2 weeks in a small stream to allow for the colonization of microbes. Leaves were then subjected for 2 weeks to four treatments: one control, where leaves stayed immersed in the stream, and three drying treatments in different settings (field, lab, and oven). Leaves were then returned to sterile water for 2 weeks of recovery. Microbial respiration declined after all drying treatments compared to the control, with the oven-dried leaves taking the longest time to recover. All drying treatments had similar respiration to each other and the control after 2 weeks of immersion recovery. Fungal communities on the leaves were assessed by polymerase chain reaction amplification of fungal DNA from leaves followed by denaturing gradient gel electrophoresis (DGGE). Most treatments had very similar communities based on phylotypes from DGGE, with little change during drying and recovery compared to immersion controls. However, the oven-dried leaves had a very different community developing during recovery. There were no differences in diversity or richness of DGGE phylotypes among treatments after recovery. Overall, the fungal communities, in our experiment, appeared resilient to the effects of short-term drying, with little change to community structure and relatively fast recovery in activity after rewetting.