柴达木盆地灌木林地和高寒草甸蒸散发特征研究

Evapotranspiration Characteristics of Shrub Land and Alpine Meadow in Qaidam Basin

柴达木盆地属于高寒干旱内陆盆地,水资源短缺,生态环境十分脆弱,蒸散发是生态系统水分耗散的主要方式,研究其变化特征对区域水资源合理开发与生态环境保护具有重要意义。本研究以柴达木盆地灌木林地和高寒草甸为观测点,采用涡动相关仪观测的2020年通量资料计算实际蒸散发量,分析不同下垫面实际蒸散发量在不同时间尺度的变化特征,并探究了气象因子与实际蒸散发量的相关性。结果表明:(1)灌木林地和高寒草甸蒸散发过程主要集中在生长季,呈正态分布,但变化范围有一定差异,高寒草甸实际日蒸散发量和实际月蒸散发量大于灌木林地。其中,灌木林地日平均蒸散发量为0.48 mm,高寒草甸日平均蒸散发量为1.28 mm;灌木林地蒸散发量8月达到峰值,为40.47 mm,高寒草甸蒸散发量7月达到峰值,为88.92 mm。(2)对于不同下垫面,气温和土壤温度变化趋势大致相同,饱和水汽压差和风速有一定差异,实际日蒸散发量与气温、土壤温度、饱和水汽压差显著相关,但是与风速相关性不大,各季节蒸散发量对各气象因子敏感程度不同,此外高寒草甸蒸散发量与土壤含水量呈显著相关。(3)不同下垫面水分消耗变化特征表明灌木林地各月水汽交换以下垫面水分消耗为主,7-8月下垫面水分消耗最为严重,高寒草甸4、6、11月下垫面以水汽吸收为主,并在6月达到水分吸收高峰期,其余月份下垫面以水分消耗为主,7月水分消耗最大。本研究通过探讨柴达木盆地灌木林地和高寒草甸实际蒸散发特征,以期为该地区水循环研究提供一定的参考。

Qaidam Basin belongs to the alpine arid inland basin,which is short of water resources and fragile in ecological environment.Evapotranspiration is the main way of water dissipation in the natural ecosystem.The study of its variation characteristics is of great significance to the rational development of regional water resources and ecological environment protection.In this study,the shrub land and alpine meadow in Qaidam Basin were taken as observation stations,and the actual evapotranspiration was calculated by using the flux data observed by eddy covariance in 2020.The change characteristics of actual evapotranspiration of different underlying surfaces in different time scales were analyzed,and the correlation between meteorological factors and actual evapotranspiration was explored.The results showed that:(1)The evapotranspiration process of shrub land and alpine meadow mainly concentrated in the growing season,and the distribution was normal,but the variation range was different,and the actual daily and monthly evapotranspiration of alpine meadow was greater than those of shrub land.Among them,the average daily evapotranspiration of shrub land was 0.48 mm,and that of alpine meadow was 1.28 mm.The evapotranspiration of shrub land peaked at 40.47 mm in August and evapotranspiration of alpine meadow peaked in July at 88.92 mm.(2)For different underlying surfaces,the variation trend of air temperature and soil temperature were roughly the same,but the vapor pressure deficit and wind speed had some differences.The actual daily evapotranspiration was significantly correlated with air temperature,soil temperature,and vapor pressure deficit,but not much related to wind speed,and the sensitivity of evapotranspiration to meteorological factors was different in each season.In addition,the evapotranspiration of alpine meadow was significantly correlated with the soil water content.(3)The variation characteristics of water consumption of different underlying surfaces showed that the underlying surface of shrub land was mainly characterized by water consumption in each month,and the water consumption was most serious in July and August.The underlying surface of the alpine meadow was mainly characterized by water absorption in April,June,and November,and reached the peak of water absorption in June.The underlying surface of the alpine meadow was dominated by water consumption in other months,with the largest water consumption in July.This study discussed the actual evapotranspiration characteristics of shrub land and alpine meadow in Qaidam Basin,in order to provide certain reference for the study of water cycle in this area.