Spatial and temporal patterns of vegetation, terrain, and greenness in the Toolik Lake and Upper Kuparuk River Region

Abstract

With a warming climate, Alaska's arctic tundra vegetation is changing. Here I use four Landsat satellite images and glacial geology, surficial geomorphology, vegetation, slope angle, aspect, and elevation maps to examine spatial and temporal patterns of greenness in the Toolik Lake and Upper Kuparuk River Region in Arctic Alaska. The 30-m resolution of the Landsat images used in this analysis allowed for detection of patterns of heterogeneity in the greenness and in the greening of the landscape. Such studies complement the finer temporal resolution of AVHRR data, which are more appropriate to detect annual variation in greenness and greening across broad regions. This study suggests that the measured changes in AVHRR derived NDVI values are likely the result of a real change in arctic vegetation and are not simply due to technical problems with AVHRR sensors. Between 1985 and 1999 the mean Landsat-derived NDVI across the Toolik Lake and Upper Kuparuk Region increased 0.076 or 15.9%. The greening detected by Landsat data occurred heterogeneously across the landscape with the most rapid change occurring in well-vegetated areas such as tussock tundra and shrubby areas, on areas of nonsorted circles, and at lower elevations.