Shift in the synchronisation of leaf decay processes in fragmented streams

Climate change will increase dry periods and droughts, which cause both, premature leaf fall and temporary fragmentation of small streams into a series of pools. This match of low or now flow situations with litter input is likely to alter litter decay in streams. We hypothesise mismatch and special interaction between physical leaching, microbial degradation and macroinvertebrate shredding. We want to manipulate pools of summer-dry streams by exposing litter packs (Alnus glutinosa (L.) Gaertn.) to assess the shift of environmental parameters, leaf mass loss rates, and leaf colonisation by microbes (fungi) and shredding macroinvertebrates. Exclusion of shredders from litterbags will give information on their relative importance. Microcosm experiments in the laboratory are conducted to isolate the effect of factor combinations (temperature, leachate, oxygen) found in the field on enzymatic activities and microbial decay rates. Feeding experiments with Gammarus pulex shall test the effect of secondary leaf compounds, critical oxygen concentration and temperature on shredding. The results will be combined in a descriptive model of leaf decay and the potential shift in the synchronisation of leaf decay processes in fragmented streams.

DFG Programme Priority Programmes

Subproject of SPP 1162:  The Impact of Climate Variability on Aquatic Ecosystems (AQUASHIFT)