Vegetation Cover Change in Yellowstone National Park Detected using Landsat Satellite Image Analysis

Vegetation Cover Change in Yellowstone National Park Detected using Landsat Satellite Image Analysis

The northern Rocky Mountains are a region where future climate warming has the potential to alter vegetation cover and surface water runoff. Results from Landsat satellite image analysis since 1987 in all unburned areas (since the 1880s) of Yellowstone National Park (YNP) showed that consistent decreases in the normalized difference vegetation index (NDVI) have been strongly dependent on periodic variations in peak annual snow water equivalents (SWE). The unprecedented decline in SWE over the past 20+ years has had significant impacts on green vegetation cover across unburned ecosystems of YNP, especially during the year 2001, during which the peak SWE levels declined to an historic low of -1.4 standard deviations of the long-term mean SWE. Landsat NDVI analysis did not detect significant upward elevation shifts in unburned vegetation canopy cover across the timberline (above 2900 m elevation) over the past 20+ years in most alpine zones of YNP. The observed dieback of whitebark pine from field observations remains a plausible explanation for lower NDVI detection at and above timberline between the years 1987 and 2010.