Evapotranspiration from a saltcedar-dominated desert floodplain: A scaling approach

摘要

The purpose of this study was to investigate evapotranspiration (ET) from a variety of scales (leaf to landscape) in saltcedar-dominated floodplain vegetation along the lower Virgin River of southern Nevada. Leaf-level gas exchange indicated that saltcedar exhibits similar stomatal conductance as the sympatric phreatophytes arrowweed, mesquite, and willow. However, sap flow in saltcedar was higher per unit sapwood area than the other species, suggesting that it maintains higher leaf area per unit sapwood area. At the stand level, saltcedar ET was found to exceed potential ET early in the summer when soils were moist and the water table was near the surface, but by late summer, after floodplain soils had dried and the water table had dropped, saltcedar ET was well below potential rates. Summer irrigation did not result in increased conductance of saltcedar for at least four weeks, suggesting that saltcedar does not utilize summer rainfall under normal conditions in the arid Mojave Desert.