Editorial: Wetland Biogeochemistry: Response to Environmental Change

Response to Environmental ChangeWetlands around the world are increasingly impacted by a shift in environmental conditions due to climate change, land use development, resource extraction, urbanization, and sea level rise, to name a few external pressures (Meng et al., 2016;Walpole and Davidson, 2018).These environmental changes can alter the hydrological regime, impacting the biogeochemical processes that govern important wetland ecosystem services, such as carbon sequestration and water storage.Biogeochemical processes in wetlands are highly dynamic (Reddy et al., 2010;Jackson et al., 2014) and involve complex interactions between hydrological processes, mineralogical transformations, bacterial and vegetation communities, and soil stores of carbon and nutrients (Cherry, 2011; U.S. EPA, 2015).Currently, our understanding of biogeochemical properties of wetlands are derived from mechanistic and statistical links between biological, geological, and chemical processes.However, how climatic and hydrological processes interact with wetland biogeochemical functions is still not well-understood.Wetland ecosystems maintain a fragile balance between soil, water, plant, microbial, and atmospheric processes, which regulates water flow and water quality (Reddy and Delaune, 2008).Even minor gradients (naturally or anthropogenically induced) in hydrological and climatic parameters (e.g., wetting and drying, flooding, freezing, and thawing, groundwater-surface water interactions, etc.) can change the ecology and (bio)geochemistry of wetlands.These changes can have profound impacts on globally important processes, such as greenhouse gas emissions.Within a wetland, there is a high degree of spatial and temporal heterogeneity of chemical properties, temperature, and water-saturation that regulates the transport and transformation of carbon, nutrients, and redox-active elements (Reddy et al., 2010;Cherry, 2011;Jackson et al., 2014).The heterogeneity results in both spatial and temporal pulses of biogeochemical activity, primarily associated with aerobic or anaerobic microbial respiration.Thus, wetlands are considered "biogeochemical hotspots" in the landscape, with an enhanced cycling of nutrients, carbon and trace metals (Megonigal, 2008;Reddy et al., 2010;Cherry, 2011).Quantifying the variability in process intensity remains challenging but is, however, critical to unravel the linkages between forcing environmental boundary conditions and biogeochemical responses.This Research Topic brings together wetland (bio)geochemists, hydrologists, biologists, ecologists, and soil scientists to share research in various areas of wetland biogeochemistry