Northern Treeline

Recent tree-ring series developed in Alaska confirm the unusual warming of the last century. Also observed are the effects of moisture stress on trees in a region where the primary stress was considered to be temperature.  Some elevational treeline sites remain primarily temperature recorders and display trends in their ring-width series similar to hemispheric-scale trends as shown by other tree-ring and  climate proxy series. Deliberate selection of moisture stressed sites, even near treeline, can produce ring-width series that show variation in moisture and potential negative effects of continued increase in temperature. In one area the same species from different sites clearly shows two widely differing responses to climate.

Longer (millennial-scale) chronologies can be developed in Alaska combining living, relict, archaeological, and driftwood samples to provide a longer time context for consideration of climatic change. Intensive field investigation in certain areas can yield a variety  of  subfossil resources for long chronology building. However great care
must be used in combining samples from different sources, even the  same species and site sources, for reliable paleoclimatic series.

Other researchers are using tree-ring studies to show the possible effects of climatic change on the forests of Alaska (eg. Berg & DeVolder and Barber et al. 2000). These investigations indicate that there may be dramatic changes in the forests of Alaska in the near future (decades).


Dr. Gordon C. Jacoby, Dr. Rosanne D' Arrigo, Nicole K. Davi and John Sakulich
Tree-Ring Laboratory, Lamont-Doherty Earth Observatory, Palisades, New York 10964

Dr. Rob Wilson, School of GeoSciences, University of Edinburgh, UK.

Dr. Greg C. Wiles, Ryan P. Mc Allister, Sara J. Skelly, Leslie McCluskey

Department of Geology, College of Wooster, Wooster, Ohio  44691