Analysis of Evapotranspiration and Water Balance of Typical Vegetation in the Sanjiangyuan Area
Vegetation evapotranspiration has a direct effect on energy conversion and water balance of ecosystem.In order to explore the time-range distribution of evapotranspiration of different vegetation and its water balance characteristics in the Sanjiangyuan area,from November 2019 to October 2020,the actual evapotranspiration of shrub(bush cinqefoil,berberis dubia,caragana jubata,salix cheilophila)and grassland(stinkgrass flower,stipa capillata,blue grass,elymus nutans,splendid achnatherum,wheatgrass,carex caespititia and kobresia pygmaea)was measured by means of lysimeter.Ang-strom′s solar empirical formula and Penman-Monteith formula were applied to estimate the condensate,and its evapotrans-piration and time-range distribution laws were investigated.The water balance characteristics of the underlying surface of different vegetation were discussed.The results are as follows.Firstly,condensation is widespread and occurs throughout the year in the Sanjiangyuan area.The annual condensation water volume ranges from 28.47 to 56.88 mm in each region,and the probability of daily occurrence of condensation water ranges from 75.68%to 95.90%.Secondly,the spatial distribu-tion of annual evapotranspiration from vegetation is uneven.The annual evapotranspiration volume ranges from 396.20 to 707.69 mm,with summer(June-August)evapotranspiration accounting for 41.69%to 70.74%of the annual evapotranspira-tion.Thirdly,the spatial heterogeneity of water balance characteristics was obvious.The water balance characteristics of bush cinqefoil,berberis dubia,caragana jubata,and salix cheilophila were basically the same,and the water balance characteris-tics were inconsistent among different forages.Overall,vegetation evapotranspiration volume was higher than the sum of pre-cipitation and condensation,and all vegetation types consumed soil water to varying degrees(8.04 to 67.68 mm).
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