HR: 10:35h
AN: C42A-02 INVITED     [Abstracts]
TI: Changing Vegetation and Fluvial Morphology in Northern Alaska Detected Using Aerial Photographs
AU: * Tape, K D
EM: fnkdt@uaf.edu
AF: Geophysical Institute, UAF, 903 Koyukok Drive, Fairbanks, AK 99775-7320
AU: Sturm, M
EM: msturm@crrel.usace.army.mil
AF: Cold Regions Research & Engineering Laboratory, Bldg. 1570, Ft. Wainwright, AK 99703
AU: Racine, C
EM: cracine@crrel.usace.army.mil
AF: Cold Regions Research & Engineering Laboratory, Lyme Rd., Hanover, NH 14223
AB: Evidence from arctic Alaska suggests that the terrestrial landscape is changing in response to documented warming. Between 1946 and 1951, several thousand low-altitude panchromatic oblique aerial photographs were taken as part of geologic reconaissance and exploration of Alaska's Arctic Slope and Brooks Range. For this study, 202 of the old photographs were re-photographed. Comparison of the old and new photographs revealed an increase in shrub cover in the last half-century. The changes were observed over a 220,000 km^2 tract of arctic tundra, and it is likely that they are more widespread. A quantitative method for comparing the photographs yielded an increase in alder shrub cover from 14 to 20%, with similar increases observed for willow and birch shrubs. This shrub expansion was observed in many landscape positions, including hill slopes, river terraces, and also river floodplains, where the increase in vegetation has resulted in narrower, more stable floodplains. Changes were also observed at treeline. 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 thought to be a product of elevated temperatures and other changes in climate favorable to shrub growth. Special attention will be given to the methods used to compare the old and new photographs.
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting