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Comparison of water vapour, heat and energy exchanges over agricultural and wetland ecosystems
Author(s) -
Li Yijun,
Zhou Li,
Xu Zhenzhu,
Zhou Guangsheng
Publication year - 2009
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.7339
Subject(s) - evapotranspiration , eddy covariance , wetland , environmental science , ecosystem , growing season , transpiration , canopy , hydrology (agriculture) , leaf area index , latent heat , atmospheric sciences , ecology , geography , photosynthesis , botany , biology , geotechnical engineering , geology , meteorology , engineering
Abstract Wetland and maize farmland are main ecosystems in Northeast China, which play important roles in water, heat and energy exchanges between land and atmosphere. In this study, we used the eddy covariance system to examine the characteristics of water, heat and energy exchanges over a rain‐fed maize agricultural ecosystem and a reed wetland ecosystem. The results showed that water and heat exchanges had significant differences between the two ecosystems, which were attributed to obvious distinction in their surface properties. Heat exchange ( H ) was stronger over reed wetland, while water vapour exchange (LE) was greater over maize farmland. Wetland has great thermal capacity that tends to slow down the energy exchange; therefore, half‐hour peak values of LE and H over the wetland delayed for half an hour compared to the maize farmland. The ratio of evapotranspiration (ET) to potential evapotranspiration (ET p ) indicated that ET over the reed wetland was most of the time close to ET p in the non‐growing season, while ET over the maize farmland was closer to ET p in the growing season. A weak linear relationship was found between ET and leaf area index (LAI) over the reed wetland in the growing season, indicating that the transpiration from canopy provided few contributions to ET. In addition, uncertain water resources brought external energy into reed wetland, resulting in poor energy closure, which provided some uncertainty to the partition of available energy. Copyright © 2009 John Wiley & Sons, Ltd.