13C Plant polymer SIP (Hainich CZE H41)

Microbial life in oligotrophic groundwater ecosystems is dependent on lithoautotrophy, ancient deposited organic carbon released from rocks, and on surface-derived allochthonous carbon inputs such as plant polymers. Here, we employed groundwater microcosm experiments with 13C-labelled plant-derived polysaccharides to identify microorganisms responsible for the degradation of these polymers, and whether the key players are distinct between groundwater and the overlying forest soil. The groundwater used was derived from well H41 of the Hainich Critical Zone Exploratory (CZE), a platform to study the links between surface and subsurface biogeosphere, located in carbonate and marlstone rocks in central Germany. Groundwater from this well is oxic, with a pH of 7.2. The soil used resembled the infiltration area of the corresponding aquifer assemblage, located in a forest area.