HR: 11:00h
AN: H22A-03    [Abstracts]
TI: Soil Zone Ecohydrology of a Semiarid Woodland at the Canopy-Intercanopy Scale
AU: * Newman, B D
EM: bnewman@lanl.gov
AF: Los Alamos National Laboratory, Earth and Environmental Sciences Division, MS J495, Los Alamos, NM 87544 United States
AU: Gard, M O
EM: mgard@lanl.gov
AF: Los Alamos National Laboratory, Earth and Environmental Sciences Division, MS J495, Los Alamos, NM 87544 United States
AU: Breshears, D D
EM: daveb@ag.arizona.edu
AF: University of Arizona, School of Natural Resources PO Box 210043, Tucson, AZ 85721-0043 United States
AB: Semiarid ecosystems are often characterized by patchy vegetation distributions. The pinon-juniper (Pinus edulis and Juniperus monosperma) woodlands of the southwestern U.S. are a good example of this patchiness where grassy/bare intercanopy patches are mixed with woody, pi¤on-juniper canopy patches. In this study, we examined how these two patch types influence ecohydrological factors such as evaporation, downward water fluxes, and nutrient (nitrate) distributions. Examination of & δD values of soil waters show statistically significant differences between canopy and intercanopy patches indicating increased evaporative removal of water in the intercanopy patches. In contrast to the isotope/evaporation data, chloride based downward water fluxes are not significantly different, suggesting that while evaporation to transpiration ratios vary between canopy and intercanopy patches, total evapotranspiration may be similar (as implied by the lack of a difference in downward fluxes). This interpretation indicates the importance of understanding the partitioning of evaporation and transpiration, and how this ratio shifts within ecosystems. It may also help explain why patchy vegetation distributions develop and persist. Patchiness also appears to be important for understanding nutrient distributions. Nitrate concentrations were drastically different between the patch types, with higher nitrate concentrations and inventories occurring in the intercanopy patches. These results highlight the importance of the canopy-intercanopy scale for understanding the ecohydrology of patchy, semiarid woodlands.
DE: 0400 Biogeosciences
DE: 1818 Evapotranspiration
DE: 1866 Soil moisture
DE: 1875 Unsaturated zone
SC: Hydrology [H]
MN: 2005 Joint Assembly