Climate Driven Vegetative Composition Changes in the Big Pine Creek Watershed Using Spectral Mixture Analysis and Time Series Analysis ofLandsat Surface Reflectance Data over a 30 Year Period

摘要

This paper presents a time series study of vegetative composition change in an alpine?ecosystem in the Big Pine Creek watershed in California’s Eastern Sierra Nevada Mountain’s. Sixteen sample sites that demonstrated same directional trends in their visible and near-IR responses were examined for changes species composition over the last 30 years using spectral mixture analysis to evaluate how warming temperatures have altered the vegetative mix of those sites. These findings are used to establish the relationship between trends in spectral reflectance and changes in vegetative composition. We found that changes in the compositional make up of a site can result in changes to the spectral response that contradict the trends in vegetative indices and Tasseled Cap transformations. At one particular site, we show that Tasseled Cap indices are all consistent with a statistically significant decline in surface cover while spectral mixture analysis demonstrates statistically significant increases in vegetative cover.