USGS Alaska Science Center Grant: Assessing Climate Impact on Alaskan Boreal-Arctic Ecosystems and Migratory Birds

The two morphological features with the greatest impact on the occurrence of bird species in the arctic and boreal forest regions of Alaska are the occurrence of water and the height of the woody vegetation, with more moderate effects of spatial heterogeneity of habitats, density of woody plants, and whether plants are coniferous or deciduous. Changes in the frequency, intensity, and extent of fires across the boreal forest and arctic tundra can alter not only the composition, age and size of the mature trees but also the patchiness of early-successional vegetation across the landscape. Thus, fire and climate are critical controlling factors of habitat structure for birds in this region, as they determine both successional stage and the range limits (both latitudinal and elevational) of important vegetation.

This research will apply downscaled climate scenarios to simulated landscapes encompassing the boreal-arctic transition zone of Alaska to evaluate potential effects of climate change on these landscapes through the end of the century. The simulation domain is broadly defined as north of the Yukon River to the northern foothills of the Brooks Range from the Seward Peninsula to the Alaska-Canada border. Landscape modeling will be conducted at 1-km2 resolution. Models will investigate potential changes in the vegetative structure and composition of avian habitats within this domain by simulating dynamics among climate, fire, and woody vegetation relative to landscape characteristics and successional stages. Projected changes in habitat will, in turn, be evaluated for their potential effects on future breeding distributions of a selected suite of migratory bird species across the boreal-arctic transition zone.

Climate change is already strongly influencing the distribution and abundance of many plant and animal species at both latitudinal and elevational margins of their ranges. Recent studies have documented significant northward shifts in breeding distributions of several species of birds in Alaska but little is understood about the ecological processes governing these changes. The boreal-arctic transition zone provides continentally critical breeding grounds for an important and unique northern avifauna. Resource managers in Alaska are concerned with potential effects of climate change on migratory bird species but to date have had little information with which to plan for possible changes in population distribution, abundance, or biodiversity. Climate change scenarios need to be downscaled to define potential future conditions across the regional and local landscape. The research solicited here will apply fine-scale climate model predictions to simulated landscapes under current conditions to evaluate what potential ecological responses to climate change can be expected. Such information is crucial for developing appropriate adaptive management strategies, including response to changing fire dynamics, that will address the potential ecological effects of climate changes on boreal and arctic migratory bird populations.