High-frequency analysis of stream chemistry to establish elemental cycling regimes in high-latitude catchments

Rapid changes in the dynamics of permafrost and fire have significant consequences for the structure and function of ecosystems at northern high-latitudes. Climate change in Alaska has resulted in increased mean annual temperature and precipitation, coinciding with decreased areal extent of permafrost and an increase in active layer depths. The fire regime has concurrently shifted toward larger and more intense fires, particularly late in the growing season. The primary goal of this project is to detect responses of biogeochemical cycles to these disturbances at the catchment scale using high-frequency measures of dissolved organic matter and nitrate in streams. High-frequency records will establish baseline conditions in catchments that vary in ecosystem configuration, providing targets for management. Analysis of high-frequency time series is also a promising avenue for differentiating the effects of “pulse” disturbances such as fire and thermokarst formation from “press” disturbances of climate warming and increased depth of the active layer, which is essential for managing high-latitude ecosystems.