Characterizing evapotranspiration over a meadow ecosystem on the Qinghai-Tibetan Plateau

• Main Authors: Gu, Song, Tang, Yanhong, Cui, Xiaoyong, Du, Mingyuan, Zhao, Liang, Li, Yingnian, Xu, Shixiao, Zhou, Huakun, Kato, Tomomichi, Qi, Peitong, Zhao, Xinquan
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2008
• Subjects: Carbon-dioxide; Energy-balance; Boreal Forest; Water-vapor; Environmental Controls; Stomatal Conductance; Temperate Grassland; Arctic Tundra; Exchange; Evaporation; 生物科学; Science & Technology; Physical Sciences; Meteorology & Atmospheric Sciences; Arctic; Priestley; Tundra
• Online Access: http://ir.nwipb.ac.cn/handle/363003/1218

To characterize evapotranspiration (ET) over grasslands on the Qinghai-Tibetan Plateau, we examined ET and its relevant environmental variables in a Kobresia meadow from 2002 to 2004 using the eddy covariance method. The annual precipitation changed greatly, with 554, 706, and 666 mm a(-1) for the three consecutive calendar years. The annual ET varied correspondingly to the annual precipitation with 341, 407, and 426 mm a(-1). The annual ET was, however, constant at about 60% of the annual precipitation. About 85% annual ET occurred during the growing season from May to September, and the averaged ET for this period was 1.90, 2.23, and 2.22 mm/d, respectively for the three consecutive years. The averaged ET was, however, very low (< 0.40 mm/d) during the nongrowing season from October to April. The annual canopy conductance (gc) and the Priestley-Taylor coefficient (a) showed the lowest values in the year with the lowest precipitation. This study first demonstrates that the alpine meadow ecosystem is characterized by a low ratio of annual ET to precipitation and that the interannual variation of ET is determined by annual precipitation. To characterize evapotranspiration (ET) over grasslands on the Qinghai-Tibetan Plateau, we examined ET and its relevant environmental variables in a Kobresia meadow from 2002 to 2004 using the eddy covariance method. The annual precipitation changed greatly, with 554, 706, and 666 mm a(-1) for the three consecutive calendar years. The annual ET varied correspondingly to the annual precipitation with 341, 407, and 426 mm a(-1). The annual ET was, however, constant at about 60% of the annual precipitation. About 85% annual ET occurred during the growing season from May to September, and the averaged ET for this period was 1.90, 2.23, and 2.22 mm/d, respectively for the three consecutive years. The averaged ET was, however, very low (< 0.40 mm/d) during the nongrowing season from October to April. The annual canopy conductance (gc) and the Priestley-Taylor coefficient (a) ...