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Advances in Meteorology
Volume 2015, Article ID 935060, 14 pages
http://dx.doi.org/10.1155/2015/935060
Research Article

Flooding Regime Impacts on Radiation, Evapotranspiration, and Latent Energy Fluxes over Groundwater-Dependent Riparian Cottonwood and Saltcedar Forests

1Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA
2Australian SuperSite Network and Terrestrial Ecohydrology Research Group, School of Life Sciences, University of Technology Sydney, P.O. Box 123, Broadway, NSW 2007, Australia
3USDA Agricultural Research Service, Grazinglands Research Laboratory, 7207 West Cheyenne Street, El Reno, OK 73036, USA
4U.S. Fish and Wildlife Service, National Wildlife Refuge System, Division of Water Resources, 500 Gold SW, Albuquerque, NM 87102, USA
5Department of Plants, Soils and Biometeorology, Utah State University, Logan, UT 84322, USA
6National Centre for Groundwater Research and Training, University of Technology Sydney, P.O. Box 123, Broadway, NSW 2007, Australia

Received 2 March 2015; Accepted 19 April 2015

Academic Editor: Marcos Heil Costa

Copyright © 2015 James Cleverly et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Radiation and energy balances are key drivers of ecosystem water and carbon cycling. This study reports on ten years of eddy covariance measurements over groundwater-dependent ecosystems (GDEs) in New Mexico, USA, to compare the role of drought and flooding on radiation, water, and energy budgets of forests differing in species composition (native cottonwood versus nonnative saltcedar) and flooding regime. After net radiation (700–800 W m−2), latent heat flux was the largest energy flux, with annual values of evapotranspiration exceeding annual precipitation by 250–600%. Evaporative cooling dominated the energy fluxes of both forest types, although cottonwood generated much lower daily values of sensible heat flux (<−5 MJ m−2 d−1). Drought caused a reduction in evaporative cooling, especially in the saltcedar sites where evapotranspiration was also reduced, but without a substantial decline in depth-to-groundwater. Our findings have broad implications on water security and the management of native and nonnative vegetation within semiarid southwestern North America. Specifically, consideration of the energy budgets of GDEs as they respond to fluctuations in climatic conditions can inform the management options for reducing evapotranspiration and maintaining in-stream flow, which is legally mandated as part of interstate and international water resources agreements.