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Changes in Meadow Vegetation Cover in Yosemite National Park (California) Based on Three Decades of Landsat Image Analysis

Christopher Potter

Changes in Meadow Vegetation Cover in Yosemite National Park (California) Based on Three Decades of Landsat Image Analysis

Meadow ecosystems can serve as sensitive indicators of climate change impacts on the Sierra Nevada region. Landsat 30-m resolution image data over the past 25 years in Yosemite National Park was analyzed to track changes in the normalized difference vegetation index (NDVI) in all meadow units of Yosemite National Park. Results showed that NDVI values from the wet year of 2010 were significantly lower than NDVI values from the comparatively dry year of 2013 in the majority of meadow areas in the National Park. This finding implied that higher surface water levels could be detected in wet years using Landsat imagery. A sequence of NDVI changes in consistently dry years over the past three decades (1990, 2001, 2007 and 2013) showed progressively higher green plant cover in the majority of meadow areas, suggesting that some encroachment of woody vegetation since the early 1990s was detectable, especially at sub-alpine meadow elevations.