Impacts of extreme precipitation events on leaf litter and wood decomposition rates

Global hydrological cycles are shifting due to climate change, and projected increases in the frequency and intensity of extreme precipitation events will likely affect essential ecosystem processes driven by climate, such as forest decomposition. Our objective was to determine the effects of drought and intense rainfall on leaf litter and wood decomposition rates. We used a precipitation manipulation experiment to demonstrate that extreme precipitation projections for the Northeastern United States will significantly impact wood but not leaf litter decomposition and that variations in substrate quality will continue to drive differences in decomposition rates. We found that drought and high rainfall reduced wood decomposition compared to historic rainfall patterns. The median mass remaining of wood stakes after three years within drought, control, and inundation treatments was 84.2%, 57.0%, and 67.5%, respectively. Furthermore, labile litter and wood substrates decomposed more rapidly than recalcitrant substrate types. Thus, our findings suggest a greater sensitivity of wood decomposition to changing precipitation regimes compared to leaf litter. Since wood represents a substantial forest carbon pool, our results underscore the possible significant impacts of projected extreme precipitation scenarios for forest functions, including carbon cycling and sequestration.