Aquatic Ecosystem Vulnerability to Fire and Climate Change in Alaskan Boreal Forests
Jeffrey Falke | U.S. Geological Survey
Fire is the dominant ecological disturbance process in boreal forests and is natural and widespread. However, fire frequency, size and severity are increasing in Alaska owing to climate warming. Interactions among fire, climate, permafrost, vegetation and hydrologic and watershed processes are poorly understood, yet critical for conservation and management of boreal aquatic habitats in a changing environment. This research will address this challenge on and around Department of Defense (DoD) lands in interior Alaska by focusing on mechanistic relationships among ecosystem drivers and the biological response to those drivers. First, through field studies the research team will quantify variation in ecohydrology and aquatic productivity across fire-impacted catchments. Second, integrated climate, terrestrial, and aquatic models will be used to identify where and when aquatic populations may be most vulnerable to fire in the future. Third, researchers will use a structured decision making framework to engage land managers in identifying conservation and management objectives and quantifying the consequences of different management scenarios applied under a suite of climate scenarios.
The research team will develop a modeling framework informed by field-based studies to identify aquatic habitats most sensitive to changes in climate and wildfire. First, they will characterize the physical and biological mechanisms driving aquatic habitat dynamics and productivity in fire impacted watersheds. Within a set of headwater catchments with varying time since fire disturbance, researchers will quantify hydrologic, thermal, and water chemistry regimes, use state-of-the-art methods to map stream habitat, and link these drivers to estimates of ecosystem productivity including primary and secondary productivity, fish bioenergetics and demographics. The research team will use recently-developed food web and fish individual-based models to then investigate the response of aquatic productivity to changing fire regimes and climate.
Second, researchers will develop an integrated modeling framework by linking spatially-explicit climate, fire, vegetation, permafrost, hydrologic, and stream temperature models parameterized for interior Alaska. They will use model output to quantify future impacts of fire and climate on aquatic habitats and population vulnerability under different scenarios of climate change and associated fire regime. Lastly, working directly with land managers, researchers will develop management objectives and scenarios to explore interactions between fire management and future climate scenarios and the effects on aquatic habitats. Researchers will develop a web-based tool to support decision making and to provide broad access to the project datasets and model simulations.
This work will increase DoD and other land managers’ capacity to project and respond to environmental change in boreal aquatic ecosystems, and develop an improved understanding of mechanistic linkages among key ecosystem processes. Digital stream habitat, climate scenarios, simulated landscape change, and web-based tools to map and analyze the data produced by this project will support a broad array of potential management decision making issues in the region, and serve as templates for fire management and climate interactions in other ecoregions. Working directly with managers researchers will identify plausible future conditions in which aquatic species can persist under expected ecosystem change. This information will be critical for current and future decision making in boreal aquatic ecosystems.