Watershed hydrology and dissolved organic matter export across time scales: minute to millennium

Abstract

Ecological theory emphasizes headwater streams and wetlands as hotspots for metabolism of terrestrially derived organic matter and biogeochemical transformations. Growing evidence indicates that freshwater ecosystems may be as important as terrestrial and marine environments in the annual flux of CO2 to the atmosphere. The National Ecological Observatory Network (NEON) and the Stream Ecological Observatory Network (STREON) offer the opportunity to collect and analyze data related to these processes at spatial scales ranging from local to continental and at temporal scales from minutes to millennia. These data can be used to understand how global climate change and subsequent shifts in terrestrial plant communities and precipitation regimes will influence the export and composition of dissolved organic matter (DOM) to headwater streams, downstream freshwater ecosystems, and coastal environments. Moreover, temporal scaling of DOM export among watersheds is an underexploited frontier research area throughout the earth sciences. Long-term, high-frequency fluorometry and discharge data sets collected at NEON and STREON observatories could be linked to evaluate, quantify, and forecast DOM export among watersheds and across time scales ranging from individual hydrologic events to decadal changes in precipitation regimes.