Shifts in plant functional community composition under hydrological stress strongly decelerate litter decomposition

Litter decomposition is a key process of nutrient and carbon cycling in terrestrial ecosystems. The decomposition process will likely be altered under ongoing climate change, both through direct effects on decomposer activity, and through indirect effects caused by changes in litter quality.

We studied how hydrological change indirectly affects decomposition via plant functional community restructuring caused by changes in plant species´ relative abundances (community weighted mean traits (CWM) and functional diversity). We further assessed how those indirect litter quality effects compare to direct effects. We set-up a mesocosm experiment, in which sown grassland communities and natural turf pieces were subjected to different hydrological conditions (dryness, waterlogging) for two growing seasons. Species-level mean traits were obtained from trait data bases and combined with species´ relative abundances to assess functional community restructuring. We studied decomposition of mixed...