Quantifying the Effects of the Mountain Pine Beetle on Melt Morphology and Timing in the Colorado River Basin, USA
Student: Danielle O. Perrot
Advisor: Noah P. Molotch, University of Colorado at Boulder: Geography | INSTAAR Dr. Gregory S. Okin, University of California, Los Angeles: Geography
The mountain pine beetle epidemic in the Colorado River Basin has resulted in widespread tree mortality in lodgepole pine stands across the Colorado Plateau. Due to the complex interactions between vegetation and snow, it is likely that changing vegetation structure will impact water yield, as snow represents the dominant input of water into these semi-arid mountain ecosystems. We hypothesize that the affected stands will experience a change in sub-canopy hydrolometeorological fluxes and surface albedo, thus influencing snowmelt rates. The result of these impacts on the basin scale hydrology is largely unknown given the complexity of these micro-scale interactions. We developed a mechanistic approach to resolve the spatio-temporal evolution of snowmelt and snowpack characteristics at the micro-scale (i.e. < 10 cm) for stages of beetle-related tree mortality using distributed hydrologic instrument clusters, hyperspectral snowpack characterization techniques, a distributed snowpack model (SNTHERM), and hemispherical photography. Our modeling results exhibit melt rates 1.1 and 3.4 times that of rates in unaffected stands for affected stands in intermediate and advanced stages of mortality, respectively. With the aid of remotely sensed snow and vegetation information, these results will provide the basis for larger scale simulations of the hydrologic impacts of beetle infestation across the Colorado River Basin.