Dendroclimatology of Alaskan Yellow Cedar
Dendroclimatology relies on exploiting climate-limited tree growth as a proxy for past climates. The temperate, mesic environments of Western Washington and Oregon do not typically provide a wealth of species or sites for climate reconstructions that extend multiple centuries. Pacific Northwest Alaskan Yellow Cedar (Xanthocyparis nootkatensis) was previously thought to be a poor paleoclimate resource due to growth asymmetries caused by buttressing and a propensity for false and missing rings. However, recent work has shown that remnant high elevation patches of Yellow-cedar are a viable and unexploited paleoclimate resource. They are also considered the oldest species in the region, with some individual living over 1800 years. In our preliminary work, we've developed a highly sensitive ring-width chronology that dates back to 1186 AD where growth is significantly correlated to temperature and distinct climatic episodes (e.g., the Little Ice Age) are well represented. With continued expansion of this project, there is very high likelihood of developing a millennial-length regional temperature reconstruction along the western Cascades where none now exists.
Species Distribution Modeling
Climate-induced range shifts are being documented worldwide, across ecosystems and taxa. The exceptional velocity of anthropogenic climate change is challenging species responses through dispersal, migration and adaptation. Will species be able to migrate quickly enough to keep track of their climatic niche? Will dispersal limitations impede migratory progress and result in local extinctions? We are working on these and other questions using species distribution modeling, a correlative approach that relates species occurrence to climate and environmental variables. By integrating independent data sets (such as genetics) we are improving the predictive capacity of these models. Calibrated predictive models can then be used to generate conservation and management recommendations that prioritize the maintenance of genetic diversity, the mitigating of extinction risks, and ecosystem stability in the face of climate change.
The Greening of the Boreal Forest
The expansion of forest vegetation within and into the Arctic is one of the profound transformations that the Arctic land surface is likely to undergo in the coming decades. The spread of forest vegetation has significant ramifications for the Arctic System, as it is likely to cause both positive and negative feedbacks on climate, and to alter the availability of crucial natural resources. Although forest expansion within and into the Arctic has been widespread in recent decades, there is growing evidence that non-linear responses to warming may prevail within areas of expanding forest. In particular, large areas of 'browning' (declining in NDVI) have recently been identified in the southern Arctic.
The Polaris Project
After "Are you crazy?", the most common question you'll get as a participant in the Polaris Project will likely be "Why would anyone want to go to the Siberian Arctic?". The answers will vary, but most will include a description of the Arctic's tremendous importance to Earth's climate system, a desire to understand how global warming is already impacting the region, an excitement about the diverse and fascinating cultures you'll be exposed to in Siberia, and yes, the draw of an almost unbelievable adventure that very few people ever get to experience. The Polaris Project includes a field course and research experience for undergraduate students in the Siberian Arctic, several new arctic-focused undergraduate courses taught by project scientists at their home institutions, the opportunity for those scientists to initiate research programs in the Siberian Arctic, and a wide range of student science projects and outreach activities. The guiding scientific theme is the transport and transformations of carbon and nutrients as they move with water from terrestrial uplands to the Arctic Ocean, a central issue as scientists struggle to understand the changing Arctic.
