ARCUS 16th Annual Meeting and Arctic Forum 2004

Shrub Increase in Northern Alaska Documented Using Repeat Aerial Photography

Kenneth Tape¹, Matthew Sturm², Charles H. Racine^3
1Geophysical Institute, University of Alaska - Fairbanks, PO Box 80425, Fairbanks, AK, 99708, USA, Phone 907-353-5171, fnkdt@uaf.edu
²CRREL - Fairbanks, AK, PO Box 35170, Ft. Wainwright, AK, 99703-0170, USA, Phone 907-353-5183, Fax 907-353-5142, msturm@crrel.usace.army.mil
³CRREL - Hanover, NH, 72 Lyme Road, Hanover, NH, 03755-1290, USA, Phone 603-646-4519, Fax 603-646-4785, cracine@crrel41.crrel.usace.army.mil

Evidence from arctic Alaska suggests that the terrestrial landscape is changing in response to documented warming and elevated carbon dioxide concentrations in the atmosphere. In this study, 202 old (1946-51) oblique aerial photographs from arctic Alaska were repeated from helicopter, and comparison of old and new photographs revealed an increase in shrub cover over the last half-century. A quantitative method for comparing photographs yielded an increase in alder shrub cover from 14-20%, and similar increases were observed for willow shrubs. This shrub expansion was observed in many landscape positions, including river floodplains, where the increase in vegetation has resulted in narrower, more stable floodplains. The pervasiveness of the change documented in the photographs can only be explained by a perturbation operating on a similarly large scale. In the absence of large-scale disturbances like fire, the increase in shrubs documented here is likely an indirect product of elevated temperatures or carbon dioxide concentrations.

Abstract Categories: Student Presentation