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Title: Tracking Greening of Alpine Watersheds: Classifying Landcover Change Via Remote Sensing
Abstract: Climate change is affecting mountain watersheds to a greater degree than other environments. Rising temperatures are increasing the ratio of rain to snow, as well as lengthening the growing season. These changes are promoting the loss of permanent snow and ice. This change is also altering the distribution, density, and type of plant cover, typically increasing biomass, known as greening. Currently, we see this greening in alpine environments mostly as new growth of tundra plants and shrubs moving up slope into previously uninhabited environments. Greening and upslope vegetation movement are well documented phenomena at broad scales, but we have less understanding of the mechanisms and distribution of greening at the watershed scale. This research will compare climate change effects on vegetation and snow persistence in a maritime montane ecosystem in south central Alaska with a dry alpine ecosystem in central Idaho. This study uses supervised classification of Landsat data to generate a time series of landcover change in the Nellie Juan Watershed in Alaska and the headwaters of the South Fork of the Payette River in Idaho from 1984 to present. We will use these data to compare the effects of climate change on the two climatically different watersheds and determine the effects of topography on vegetation and perennial snow distribution, as well as the interactions between changing vegetation and snow patches. We hypothesize that vegetation is moving upslope and densifying at a rapid rate due to more intense climate change effects at high elevations. We expect to see these changes manifest as new growth of tundra vegetation at high elevations and replacement of tundra vegetation by shrubs at middle elevations. We also expect to see snow persist longer on new shrub stand edges due to snow drifting and shading, and an earlier onset of melt at the highest elevation snow patches due to increased temperature, which will promote more vegetation growth directly below these snow patches. This research will show how key components controlling hydrologic partitioning, namely vegetation and snowpack, are changing in mountain watersheds, giving insight to how water is stored in a changing climate.
Advisor: Anna Bergstrom
Committee Members: Ellyn Enderlin, Jim McNamara, Joshua Koch