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Ecohydrology in the Great Basin: Plants and Water in Arid Ecosystems
Bob Nowak, Professor, University of Nevada-Reno, Reno, NV
Ecohydrology is the scientific discipline that examines interactions between the hydrologic cycle and ecosystems. Ecohydrology explicitly recognizes that the hydrologic cycle affects plants and that plants influence system hydrology. Using the Great Basin and its predominantly arid plant communities as a backdrop, I examine how hydrologic cycles influence plants at continental, regional, and localized scales. Both the amount and timing of both precipitation and potential evapotranspiration influence how the hydrologic cycle influences plants. Plants also influence water cycling and balance through plant influences on water redistribution in the soil profile and through species and microsite effects on soil water balance.
In the arid Great Basin environment, three ecohydrologic patterns emerge. First, with few exceptions, plants extract all available water from the soil profile during the growing season. Second, peak soil moisture occurs relatively early in the growing season, well before peak standing crop. Third, maximum rooting depths are often greater than mean annual wetting depths of the soil profile. Hydrologic and ecologic implications of these patterns, including those related to restoration, groundwater recharge, and global environmental change, are discussed.