Spatial relationships between snow and ecosystem properties in a Wyoming alpine treeline ecotone: linking simulations and observations

Interactions among wind, topography, vegetation, and snow create a heterogeneous snow distribution in uppertreeline ecotones. These repeating patterns affect vegetation and biotic processes by determining the localabundance of water and growing season length. Spatial patterns of environmental variables determine aspects ofecosystem structure and function. These ecosystem components feed back and modify physical environmentalcharacteristics. Understanding spatial patterns of ecosystem properties requires simulation of physical processes ina spatially distributed manner, validation of these simulations, and exploration of how changes in driving variablesalter spatial patterns on this landscape. Simulation of snow redistribution by wind, subsequent melting of thesnowpack, and meltwater flow was performed for a 6.25 km2 area during the 1999-2000 water year. Ecosystemproperties'(e.g., snow depth and density, soil moisture, soil temperature, vegetation cover) were measured along aseries oftransects during spring and summer 2000. These properties were used to estimate model error andevaluate the possibility of accounting for the importance of moisture movement (snow and liquid) and growingseason length in this landscape.