Wide-area ratios of evapotranspiration to precipitation in monsoon-dependent semiarid vegetation communities

Journal of Arid Environments
By: , and 

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Abstract

Evapotranspiration (ET) and the ratio of ET to precipitation (PPT) are important factors in the water budget of semiarid rangelands and are in part determined by the dominant plant communities. Our goal was to see if landscape changes such as tree or shrub encroachment and replacement of native grasses by invasive grasses impacted ET and ET/PPT and therefore watershed hydrology in this biome. We determined ET and ET/PPT for shrublands, grasslands and mesquite savannas in southern Arizona at five moisture flux towers and determined the environmental factors controlling ET in each plant community. We then scaled ET over areas of 4–36 km2, representing homogeneous patches of each plant community, using the Enhanced Vegetation Index (EVI) from MODIS sensors on the Terra satellite. Over wide areas, estimated ET/PPT projected from MODIS EVI ranged from 0.71 for a sparsely-vegetated shrub site to 1.00 for grasslands and mesquite savannas. The results did not support hypotheses that encroachment of mesquites into grasslands or that replacement of native grasses with introduced Eragrostis lehmanniana (lehmann lovegrass) have increased rangeland ET.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Wide-area ratios of evapotranspiration to precipitation in monsoon-dependent semiarid vegetation communities
Series title Journal of Arid Environments
DOI 10.1016/j.jaridenv.2015.02.010
Volume 117
Year Published 2015
Language English
Publisher Elsevier
Contributing office(s) Southwest Biological Science Center
Description 12 p.
First page 84
Last page 95
Country United States
State Arizona
Online Only (Y/N) N
Additional Online Files (Y/N) N
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