Kathi Guelland (WSL Birmensdorf, Switzerland)
"Initial development of carbon fluxes along a soil chronosequence of a glacier forefield – a labelled litter experiment"


In Swiss Alps, 90% of the glaciers have a negative mass balance leading to exposure of fresh rocks on unvegetated land surfaces. Young soils developing in glacier forefields are accumulating C. The goal of this study is to investigate the influence of initial soil development on the C cycling in a glacier forefield. To identify fate, turnover and transformation of new litter C and old SOM in different soil ages we added isotopic labelled litter along a chronosequence at Damma Glacier forefield, Switzerland. Results show an exponential increase in soil C within each soil age and a gap between the different soil ages. Annual rates of soil respiration, compared to net C accumulation, indicate that the latter is an order of magnitude lower than the annual flux of C through the system. At the younger sites, the contribution of litter to soil CO2-efflux was 3 times higher. Leaching of DOC increased similar to respiration. Only a small fraction of the plant C inputs is accumulating in soils.