HR: 10:50h
AN: C41D-03    [PDF]
TI: Vegetation and Variable Snow Cover: Spatial Patterns of Shrubland, and Grassland Snow
AU: * Liston, G E
EM: liston@atmos.colostate.edu
AF: Department of Atmospheric Science, Colorado State University, 1371 Campus Delivery, Fort Collins, CO 80523-1371 United States
AU: Hiemstra, C A
EM: hiemstra@atmos.colostate.edu
AF: Department of Atmospheric Science, Colorado State University, 1371 Campus Delivery, Fort Collins, CO 80523-1371 United States
AU: Strack, J E
EM: jstrack@atmos.colostate.edu
AF: Department of Atmospheric Science, Colorado State University, 1371 Campus Delivery, Fort Collins, CO 80523-1371 United States
AB: Regions that experience long winters with snowfall and high winds frequently exhibit heterogeneous snow distribution patterns that arise from interactions among snow, wind, topography, and vegetation. Variable snow cover and resultant heterogeneities in albedo and growing season length can affect local weather patterns and energy budgets, and produce spatially co-variable ecosystem properties. While snow influences local atmospheric processes and ecosystems, an important and underappreciated feedback exists between vegetation and snow cover. Plant size, canopy density, and rigidity determine how much snow accumulates on the lee side of individual plants (e.g., shrubland vs. grassland). In addition, the canopy can also influence how much energy reaches the snowpack, thereby hindering or accelerating snowmelt. An overhanging canopy reduces incoming solar radiation while providing a source of turbulent sensible and longwave radiative energy. Historically, most snow vegetation interaction studies have been limited to areas that experience an abundance of snow (e.g., mountainous areas) where trees have a large influence on seasonal snow-cover. In contrast, snow cover patterns associated with shrublands and grasslands have received little attention, despite covering vast expanses (53%) of the seasonally snow-covered globe. In this study, snow depths were measured every two weeks from December through March in a small, 0.25 km$^{2}$ study area located in North Park, Colorado. The study area possesses little topographic relief and consists of shrub patches, dominated by greasewood ({\it Sarcobatus vermiculatus}) and sagebrush ({\it Artemisia tridentata}), embedded in a matrix of graminoids (sedges, rushes, and grasses). Snow cover patterns and spatial statistics were dramatically different in graminoid-dominated cover compared with shrub cover. The graminoid snow cover was thinner, less variable, and more ephemeral than the shrub snow pack. Snow was readily eroded by wind from graminoid areas and deposited into the shrub patches, where drifting on the lee sides of individual shrubs was apparent. As a result, the snow cover over graminoid species was shallow and ablated quickly. In contrast, shrubs accumulated deeper snow that persisted longer. Variable snow accumulation patterns, their respective effects on snowpack characteristics, ecosystem properties, and the implications of these variable snow regimes for climate models and in terms of vegetation cover change are described.
DE: 1851 Plant ecology
DE: 1863 Snow and ice (1827)
DE: 1878 Water/energy interactions
DE: 3322 Land/atmosphere interactions
SC: Cryosphere [C]
MN: 2003 Fall Meeting