HR: 1340h
AN: B33D-1062    [Abstracts]
TI: Spatial patterns of ecohydrologic properties on a hillslope and alluvial fan transect, Sevilleta Long Term Ecological Reserve, New Mexico
AU: * Bedford, D R
EM: bedfordd@colorado.edu
AF: Department of Geological Sciences, University of Colorado, Boulder, CO 80309 United States
AU: * Bedford, D R
EM: bedfordd@colorado.edu
AF: U.S. Geological Survey, 345 Middlefield Rd MS973, Menlo Park, CA 94025 United States
AU: Small, E E
EM: Eric.Small@colorado.edu
AF: Department of Geological Sciences, University of Colorado, Boulder, CO 80309 United States
AB: Spatial patterns of ecohydrologic properties allow researchers to examine spatial interactions between hydrologic, ecologic, soil, and climate parameters. Arid ecosystems are generally water limited, therefore the distribution of available moisture is extremely important. We use the spatial patterns of ecohydrologic properties to understand plant strategies to increase their water supply. In particular, we are interested in the degree of spatial self-organization of vegetation and its effects to maximize plant water availability. Small-scale measurements of surface microtopography (n~8,000 total), infiltration rate (n~400), soil texture (n~800), and vegetation have been made on six 100 m² plots along a transect within the Sevilleta Long Term Ecological Reserve. The transect is located in the shrubland ecotone and spans a hillslope and alluvial fan landform. These data have been collected to investigate how spatial patterns change along the transect to understand the relationships between hydrology, vegetation, soils, and geomorphology. We use statistical and geostatistical techniques to analyze the data. Preliminary results show that relationships between ecohydrologic properties are strongly dependant on vegetation and landscape position. In general, vegetation cover decreases while the number of species increases with higher slope and drainage area. Microtopography and infiltration rates are higher under vegetation and decrease away from plant centers. Microtopographic relief tends to increase as landscape slope and drainage area increase. Significant differences in soil texture (amounts of sand, silt, clay, organic matter, bulk density) exist under vegetation compared to vegetation interspaces. Microtopography, infiltration rate, and texture are all spatially correlated with vegetation pattern (quantified as the distance from nearest shrub). The magnitude of geostatistic correlations and correlation distances both tend to decrease with increasing landform slope and drainage area. All variables analyzed showed significant anisotropy, with the direction of maximum continuity in the general direction of maximum slope of the plot. Our data suggests that vegetation is responsible for much of the spatial variability in ecohydrologic properties. Ecohydrologic properties are also anisotropic in the direction of slope, suggesting that slope-driven processes are also driving variation. The relative effects of vegetation tend to decrease with slope and drainage area. This suggests that effects of vegetation are moderated by other processes such as overland flow and erosion.
DE: 0439 Ecosystems, structure and dynamics (4815)
DE: 0476 Plant ecology (1851)
DE: 1809 Desertification
DE: 1813 Eco-hydrology
DE: 1838 Infiltration
SC: Biogeosciences [B]
MN: Fall Meeting 2005