WWETAC Projects

Project Title: Biophysical limitations, migration potential, and climatic ranges of tree species in the interface between the boreal forest and the temperate rainforest in Alaska: an information synthesis

Principal Investigator:   Tara Barrett


Patrick Sullivan, Department of Biological Sciences, University of Alaska Anchorage
Robert Pattison, Resource Monitoring and Assessment, Pacific Northwest Research Station

Key Issues/Problem Addressed:

Three major biomes intersect in the south-central region of Alaska: the western edge of the coastal rainforest, the southern edge of the boreal forest, and the eastern edge of the mostly treeless tundra and shrub ecosystems of southwest Alaska.  Predictions of climate change responses for these ecosystems vary widely and substantial vegetation changes in this area will have large impacts on the area economy.  This study will evaluate tree species’ vulnerability to climate change in this area of AK.

Setting and Approach:  

Vulnerability assessments for individual tree species in south-central Alaska will be created based on reviews of individual species’ biophysical limitations and the best available information on their current regeneration, growth and mortality.  Current distributions and migration potentials will be reported and synthesized. Hypotheses for future distributions (and mechanisms of dispersal) of tree species will be developed using future climate scenarios and the synthesized information on biophysical limitations. A small scale pilot study of mountain hemlock along the rainforest to boreal gradient on the Kenai Peninsula will be used to evaluate historic growth (using tree-rings).  The pilot study will be designed to provide a foundation for a larger project to more fully test future distribution hypothesis and assess the potential of assisted migration of vulnerable tree species.

Progress to Date:

In the spring of 2012, the Chugach National Forest began a “Climate Vulnerability” assessment that provided a good outlet for presenting results from this project on potential migration of tree species in the south-central Alaska region. Tara Barrett and Robert Pattison participated in the workshop for this assessment on 2/2/2012 and 2/3/2102 at the University of Alaska Anchorage and worked with other participants to outline a chapter in the assessment focused on vegetation change in relation to climate in south-central Alaska.  We created a climate envelope model of the three spruce species in the region (Picea sitchensis, Picea glauca, and Picea mariana) and provided results of the model to the vegetation/wildlife group both in a written summary and in an informal presentation on 5/30/2012. The literature review on migration potential is near completion.


The synthesis report will provide greatly reduced uncertainty for land managers who need to understand potential major shifts in vegetation life form before they can assess related impacts (fire suppression and fuel treatment issues;  reserve planning for wildlife; changes in CWD inputs to streams; large-scale mortality of existing trees; need for facilitated migration).