| Fifty to eighty percent of the precipitation in a Wyoming alpine treeline ecotone arrives in the form of snow that accumulates from October to May. During this period, snow is transported by high, westerly winds to portions of the landscape where wind speeds are reduced (e.g., lee side of trees and hills), resulting in a heterogeneous snow cover. The distribution of snow cover affects ecosystem properties by determining the local abundance of water, temperature regime, and growing season length.; Understanding the underlying causes of heterogeneously distributed ecosystem properties in this landscape required simulation of physical processes in a spatially distributed manner, validation of these simulations, and exploration of how changes in driving variables alter patterns on this landscape. Simulation of snow redistribution by wind, subsequent melting of the snowpack, and meltwater flow were performed for a 6.25 km2 treeline modeling domain in south-central Wyoming during three years (1997--2000). In addition, snow depth and density, soil moisture, soil temperature, plant species composition and cover, biomass, gross decomposition, and gopher activity were measured along a series of transects. These properties were used to estimate model error and evaluate the importance of water movement and growing season length.; Four main research arenas were spatially detailed: snowpack and resultant meltwater distribution, cover types, decomposition, and gopher activity. Model simulations successfully represented the general spatial patterns of snow redistribution and ablation, but field measurements of snow depth, ablation, and soil properties indicated the need for model improvements. Cover types varied with snow depth, meltwater flow, and soil temperature in this landscape. Decomposition rates changed with litter type, soil moisture, soil temperature, snow depth, and length of time buried beneath snow. Gopher activity was inversely related to soil moisture and positively related to soil depth, soil temperature, snow water equivalent, and graminoid biomass. |
