Areal changes of land ecosystems in the Alaskan Yukon River Basin from 1984 to 2008

Multivariate alteration detection (MAD) and Bayesian inference (BI) methods are used to analyze land cover changes with Landsat images for the Alaskan Yukon River Basin from 1984 to 2008. The US Geological Survey National Land Cover Database 2001 (NLCD 2001) is treated as reference information to detect the changes. It is found that the regional land cover change has three general trends with various potential causes during the study period: (1) forests decreased mainly due to wildfire, (2) the closed water bodies were shrinking possibly due to permafrost degradation if water drains well in discontinuous permafrost regions, (3) shrubs had expanded and a large portion of grassland was converted into shrubland likely due to forest fire and warming. The uncertainty of this analysis may mainly arise from image acquisition date differences and illumination angles and remaining cloud contamination to the images. This study provides a method to analyze land cover changes with Landsat data for other regions. The developed land cover data should help future understanding of permafrost dynamics, biogeochemistry, hydrology and regional climate in the region.