Experimental Study on Natural Vegetation Evapotranspiration in Hyperarid Region

Long-term experimental study on single/community evapotranspiration of different vegetation in hyperarid region was conducted by using automatic observation instruments.Some results were given out as following: the monthly maximum evapotranspiration of Populus euphratica leaves is in August,the minimum evapotranspiration in October.In the growing season,the diurnal variation of evapotranspiration of Populus euphratica is single peak pattern,and the unit area stem water flow amount is 0.13~0.15 L·cm-2·d-1 in April and May,0.294 L·cm-2·d-1 in June.In clear sky condition,the diurnal variation of evapotranspiration of Tamarix ramosissima is single peak pattern,and daily evapotranspiration in growing season is 63.48 L,mean is 0.349 L.Daily evapotranspiration of Haloxylon ammodendron is strong related with oil moisture;the total evapotranspiration is 344.66 L in the whole growing season.Monthly evapotranspiration variations of Alhagi spassifolia,Sophora alopecuroides and Karelinie caspia appear similar regulation.Monthly and yearly evapotranspiration decreased from Alhagi spassifolia,Sophora alopecuroides to Karelinie caspia.It was calculated that the yearly vegetation evapotranspiration in the Ejin oasis is 2.43×108 m3,which provide the basic data for calculating the regional water requirement and ecological water need in future.