HR: 0800h
AN: H51D-1169    [Abstracts]
TI: Soil Hydrologic Response and Nutrient Movement in Three Small Tropical Catchments
AU: * Pullen, N H
EM: hoalst@colorado.edu
AF: University of Colorado, Department of Geography Campus Box 260, Boulder, CO 80309 United States
AU: * Pullen, N H
EM: hoalst@colorado.edu
AF: INSTAAR, Campus Box 450, Boulder, CO 80309 United States
AU: Hamann, H B
AF: Colorado College, 14 E. Cache la Poudre St., Colorado Springs, CO 80903 United States
AU: Stallard, R F
AF: US Geological Survey, 3215 Marine St. E127, Boulder, CO 80303-1066 United States
AU: Stallard, R F
AF: Smithsonian Tropical Research Institute (STRI), Apartadao 2072, Balboa Ancon, 99999 Panama
AB: The movement of water over and through soils by storm-generated flowpaths in tropical forests not only mediates nutrient movement and physical weathering, but also potentially influences vegetation growth and dynamics with seasonally dry or saturated soil conditions. However, few small-scale catchment studies (10-1000ha) have produced a comprehensive, standardized dataset on soil hydrologic properties among tropical forest catchments, due in part to complexities within tropical systems, and to inconsistencies in methods, data collection, and/or analyses. In response, this study has utilized the global, standardized network of forest dynamics plots of the Center for Tropical Forest Science (CTFS) for the rapid assessment of soil saturated hydraulic conductivity (Ks) and the water chemistry from storm-generated flowpaths. Ks measurements at varying depths help in testing Elsenbeer's (2001) functional classification continuum of tropical forest soilscapes and resulting hydrologic flowpaths. In Barro Colorado Island, Panama, Ks decreased rapidly with soil depth where horizontal surface and near-surface flowpaths were most prevalent. Ks measurements in Yasuni National Park, Ecuador indicated limited vertical movement of water at depths $>$15cm due to an impermeable soil layer. Ks measurements from Lambir Hills National Park, Malaysia, represented both ends of the continuum due to variability in soil type and lithology. In relation to soil hydrology and hydrological flowpaths, runoff chemistry at Yasuni reveals a general pattern of increased nutrient export as water moves through the canopy and over the soil surface, with concentrations of K+ increasing significantly in throughfall, and concentrations of both K+, and NO3- remaining high in overland flow. The results from the composite overland flow samples may indicate a more open nutrient cycle in tropical forest environments than has been suggested from earlier studies using radioactively labeled isotopes.
DE: 1806 Chemistry of fresh water
DE: 1860 Runoff and streamflow
DE: 1866 Soil moisture
DE: 0400 Biogeosciences
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting