Wetlands are widely acknowledged to be among the most biogeochemically active ecosystems on Earth. Much of their biogeochemistry is dictated by their high plant productivity, which captures significant amounts of carbon from the atmosphere. This carbon is then deposited as organic matter (OM) in wetland soils and sediments, where anaerobic conditions suppress decomposition and result in long-term carbon storage. Variations in microbial activity in wetland soils are thus inextricably linked with the plant community either via the microbial response to living vegetation (e.g., response to root exudates) or through microbially-mediated decomposition reactions of plant-derived OM. However, the nature of these relationships is modulated by environmental factors such as moisture availability and soil chemistry, which can overshadow plant-microbe-OM interactions. The research presented here uses a combination of approaches from molecular microbial ecology and ecosystem science to investigate linkages between the genetic potential of wetland microbial consortia and its overall function, with particular emphasis on understanding how hydrology can overlap with plant-microbial interactions to influence biogeochemical cycling.
Results/Conclusions
This research explores the coupling of microbial community structure and function in an emerging freshwater wetland. Analysis thus far has demonstrated a clear correlation between the plant community and microbial diversity, which is moderated by environmental effects - particularly soil saturation. For example, decomposition rates and extracellular enzyme analysis both demonstrate a marked change in microbial activity based on plant diversity and productivity, but the magnitude of the effect depends on soil saturation. Furthermore, hydrology dictates soil physiochemical properties, which indirectly affects vegetation and microbial community composition, so it is challenging to infer causal relationships. Information such as this is necessary if we are to develop a predictive understanding of the response of wetland ecosystems to global change that appropriately considers both the structure and function of the resident microbial communities.
