Long‐term variability in the water budget and its controls in an oak‐dominated temperate forest |
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| Authors: | Jing Xie Ge Sun Hou‐Sen Chu Junguo Liu Steven G McNulty Asko Noormets Ranjeet John Zutao Ouyang Tianshan Zha Haitao Li Wenbin Guan Jiquan Chen |
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| Institution: | 1. College of Soil and Water Conservation, Beijing Forestry University, Beijing, China;2. Department of Environmental Sciences, University of Toledo, Toledo, OH, USA;3. Eastern Forest Environmental Threat Assessment Center, Southern Research Station, USDA Forest Service, Raleigh, NC, USA;4. College of Nature Conservation, Beijing Forestry University, Beijing, China;5. Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC, USA;6. Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China;7. International Center for Ecology, Meteorology and Environment (IceMe), School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing, China |
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| Abstract: | Water availability is one of the key environmental factors that control ecosystem functions in temperate forests. Changing climate is likely to alter the ecohydrology and other ecosystem processes, which affect forest structures and functions. We constructed a multi‐year water budget (2004–2010) and quantified environmental controls on an evapotranspiration (ET) in a 70‐year‐old mixed‐oak woodland forest in northwest Ohio, USA. ET was measured using the eddy‐covariance technique along with precipitation (P), soil volumetric water content (VWC), and shallow groundwater table fluctuation. Three biophysical models were constructed and validated to calculate potential ET (PET) for developing predictive monthly ET models. We found that the annual variability in ET was relatively stable and ranged from 578 mm in 2009 to 670 mm in 2010. In contrast, ET/P was more variable and ranged from 0.60 in 2006 to 0.96 in 2010. Mean annual ET/PET_FAO was 0.64, whereas the mean annual PET_FAO/P was 1.15. Annual ET/PET_FAO was relatively stable and ranged from 0.60 in 2005 to 0.72 in 2004. Soil water storage and shallow groundwater recharge during the non‐growing season were essential in supplying ET during the growing season when ET exceeded P. Spring leaf area index (LAI), summer photosynthetically active radiation, and autumn and winter air temperatures (Ta) were the most significant controls of monthly ET. Moreover, LAI regulated ET during the whole growing season and higher temperatures increased ET even during dry periods. Our empirical modelling showed that the interaction of LAI and PET explained >90% of the variability in measured ET. Altogether, we found that increases in Ta and shifts in P distribution are likely to impact forest hydrology by altering shallow groundwater fluctuations, soil water storage, and ET and, consequently, alter the ecosystem functions of temperate forests. Copyright © 2013 John Wiley & Sons, Ltd. |
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| Keywords: | evapotranspiration water budget interannual and seasonal variability climatic warming eddy‐covariance temperate deciduous forest |
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