Study On Water Consumption Characteristics Of Typical Forests In Loess Alpine Region,in Datong County,Qinhai Province

In order to provide proof for tree species selection in loess alpine region,In this study,four typical plantations of Picea crasslia,Larix principis-rupprechtii,Populus cathayana,and Betula platyphylla were used as research objects.32 Plant Stem Flow Observation System and Davids Portable Automatic Weather Station for long-term continuous observation of the growing season of each forest land,combined with the positioning flux method to analyze the water consumption characteristics of several typical tree species and their forest land Water consumption.Main research results are as follows:(1)The empirical models for the calculation of canopy net radiation,canopy extinction coefficient,and canopy overall stomatal resistance in different forests were determined,combined with the Penman-Monteith equation model to derive the transpiration of several typical forests in the growing season of 2019 in the test area,and Picea crasslia measured transpiration data is taken as an example,and the calculated and measured values are verified by simulation.The results show that the relative error between the two is within 12%,indicating that the calculated results are more reliable.(2)Each month from forest transpiration seasonal variation,from June to August of the year forest transpiration maximum period of more than 60% of the growing season transpiration.(3)15 to 30 years of Picea crasslia growing season transpiration is 337.70 mm-370.69 mm;20-30 years of Larix principis-rupprechtii transpiration is 373.27mm-395.78 mm;30 years of Populus cathayana transpiration is 399.71mm-405.34 mm;20 years of The transpiration of Betula platyphylla ranges from 384.02 mm-406.6 mm.Transpiration differences among 4-aged little,but the same stand,the greater the age of the forest stand growing season transpiration higher water consumption.(4)The soil moisture changes between different forest lands are obviously different,but the characteristics of soil moisture profiles are generally the same,showing that the soil moisture content increases and decreases first with the increase of soil depth.When soil depth of 0-40 cm,dramatic changes in soil water content with depth,the depth to which the change significantly decreased,and the depth in the soil when 120 to 200 cm,soil moisture tends to change stable with depth of the soil.(5)According to Penman's formula,growing season evapotranspiration study area and surface evaporation are 708.13 mm and 993.93 mm,and both consistent trend curve,Comprehensive meteorological factors are reflected.