祁连山不同坡向草地蒸散量及其影响因子的分析

Study on grassland evapotranspiration at different slope orientation and its impact factors in Qilian Mountains

为了揭示祁连山山区草地的蒸散量变化规律,利用小型蒸渗仪(Micro-lysimeter)对祁连山西水林区不同坡向草地的蒸散量进行实测,并基于样地土壤调查数据和同期气象数据,对祁连山不同坡向草地的蒸散量变化规律及其有关影响因子进行了综合分析。结果表明:(1)不同坡向草地蒸散量季节动态规律均表现为单峰型,在7、8月达到蒸散量的峰值。(2)草地蒸散量变化规律:对照裸地蒸散量>草地蒸散量,阴坡草地蒸散量>阳坡草地蒸散量。(3)草地蒸散量以土壤蒸发为主;草地降水的绝大部分消耗于草地蒸散。(4)对草地蒸散量与影响因子的相关性进行分析,按相关系数排序,阳坡为:降水量(P)>气温(T)>空气相对湿度(HR)>风速(u2)>土壤含水量(θm)>太阳辐射(Ra);阴坡为:降水量(P)>气温(T)>太阳辐射(Ra)>空气相对湿度(HR)>风速(u2)>土壤含水量(θm);降水量、气温与草地蒸散量之间具有较高的线性相关(R2=0.861)。

In order to reveal the change rules of grassland evapotranspiration in Qilian mountains, the micro-lysimeter was used to measure the grassland evapotranspiration at different slope orientation. Based on the soil survey and meteorological data, the changing rules of grassland evapotranspiration and theirs impact factors were investigated. The results are as follows：（1） the seasonal dynamic patterns of grassland evapotranspiration both in sunny and shady slope showed a single peak type, reaching a peak in July or August. （2） the grassland evapotranspiration changed according to the following rule：bare land evapotranspiration〉grassland evapotranspiration, and grassland evapotranspiration at shady slope〉grassland evapotranspiration at sunny slope. （3） the grass evapotranspiration was mainly consumed at soil evaporation;grassland rainfall most consumed by grassland evapotranspiration. （4） the correlated coefficients between grassland evapotranspiration and theirs impact factors were sorted as： precipitation （P） 〉 air temperature （T） 〉 air relative humidity （HR）〉wind speed （u2）〉soil water content （θm）〉solar radiation （Ra） at sunny slope;precipitation （P）〉air temperature （T）〉solar radiation （Ra）〉air relative humidity （HR）〉wind speed （u2）〉soil water content（θm） at shady slope;the precipitation and air temperature has a significant linear relationship with grassland evapotranspiration （R2=0.861）.