HR: 10:20h
AN: H52C-01 INVITED     [Abstracts]
TI: Integration of ecohydrological processes in space and time: insights from stable isotope measurements in the soil-plant-atmosphere continuum
AU: * Williams, D G
EM: dgw@uwyo.edu
AF: University of Wyoming, Dept. 3354 1000 E University Ave., Laramie, WY 82071 United States
AB: Isotope hydrology has helped to crystallize our understanding of the origin, flow, age and fate of water in terrestrial landscapes. Within an ecohydrological context, stable isotope measurements are providing new insight into interactions and feedbacks between vegetation and the water cycle. Subtle variations in isotopic signatures within the soil-plant-atmosphere continuum provide unique information about how plant ecophysiology controls the hydrologic cycle and on the spatial and temporal integration of these processes. Beyond the fairly routine application of isotopes to identify source water used by plants, the approach is rapidly expanding in ecohydrological studies for investigations of carbon-water cycle interactions and biosphere-atmosphere gas exchange processes. The isotopic signature of water vapor released by transpiration often is very distinct from that derived from soil and open water evaporation allowing the partitioning of evapotranspiration fluxes at ecosystem and larger scales. Partitioning of these fluxes provides key insight into biosphere-atmosphere interactions and a clearer understanding of the drivers of ecosystem change. The oxygen isotope ratio of leaf and soil water are becoming increasingly important for understanding patterns and dynamics of photosynthesis and respiration at ecosystem to global levels. Carbon dioxide that exchanges with leaves and soil carries an oxygen isotope signature of the water present in those ecosystem components, and thus provides a powerful tool for resolving sources and sinks of CO2 exchange. However, there are still many uncertainties in the application of isotopes in these types of studies. In parallel with recent advances in modeling, several international monitoring efforts are underway to characterize variation in these isotopic signals, eventually leading to a better understanding of vegetation-hydrology interactions at ecosystem to global scales.
DE: 1813 Eco-hydrology
DE: 1818 Evapotranspiration
DE: 1836 Hydrological cycles and budgets (1218, 1655)
DE: 1843 Land/atmosphere interactions (1218, 1631, 3322)
SC: Hydrology [H]
MN: Fall Meeting 2005