Flooding farm fields, draining wetlands, and damming rivers: The effects of hydrologic regime change on nutrient cycling
An ecosystem’s hydrology is one of the strongest driving forces determining its structure, function, and rate at which it supplies valued services (e.g., denitrification). Globally, ecosystems are experiencing hydrologic regime changes outside of their historical range due to human engineering projects and climate change. The intensity of change is such that complete ecosystem transformation is common: rivers are transformed to lakes as dams and reservoirs are built, upland soils are converted to wetlands as treatment wetlands are constructed, etc. In some cases, natural hydrologic fluctuation has been repressed: floodplains are disconnected from rivers, wetlands are drained for agriculture, and lake water levels are stabilized. Many systems that previously experienced seasonal or decadal flooding and/or drying have now lost these natural pulses of water, energy, and nutrients. These drastic changes increase the importance of quantifying processes across entire hydrologic gradients: from flooded to desiccated, from stable to fluctuating. Comparing effects of hydrologic regime change on nutrient cycling across LTER sites, particularly by contrasting sites from the more heavily managed urban and agricultural LTERs with less managed locations, could provide useful insights for ecologists and ecosystem managers weighing ecosystem service trade-offs between different hydrologic management scenarios. The goal of this working group is to initiate a cross-site synthesis of LTER research pertaining to the effects of hydrologic regime change on ecosystem function, specifically related to the cycling of carbon, nitrogen, and phosphorus, and to explore ideas and data availability. Ultimately, we plan to form a cooperative group that will synthesize new ideas, explore previous research, and/or analyze existing LTER data for publication.