Abstract: Maowusu sandland is a typical dry and semi dry sandland in China.Water is the most important limited factor there.It is greatly affected for distribution pattern of terrestrial ecosystem and natural environment with great global change,especially global precipiatation change.The response of transpiration is investigated for seedlings of S.psammophylla, a dominant shrub in Maowusu sandland,to the global precipitation change by artificially controlling four water supply levels of 157.5 mm、315 mm、472.5 mm and 630 mm.The results show that evapotranspiration of S.psammophylla seeding increased with the increase in water supply in Maowusu sandland.The average daily evapotranspirations for four levels of water supply were 1.63 mm、3.11 mm、4.37 mm and 5.66 mm,respectively.And the evaporation contributed the main part in evapotranspiration.Transpiration rate of the seedlings showed strongly midday depression under low water supply,but not under full water supply.Correlation analysis showed that meteorological variables,such as containing water rate of sandland,photosynthetic available radiation,air temperature,saturated water vapour pressure difference,and physiological variables,such as leaf area index,leaf temperature,stomatal conductance,affected transpiration of S.psammophylla seedlings.

Key words: Simulated precipitation, Mawousu sandland, S.psammophylla seedlings, Evapotranspiration

摘要： 选择毛乌素沙地优势灌木沙柳为对象,研究15.5、315、42.5和630mm4种人控年降水量,对沙柳幼苗蒸发蒸腾作用的影响.结果表明,沙柳蒸发蒸腾量随着降水量的增加而逐渐增大,从15.5mm增至630mm,日蒸散量分别为1.63、3.11、4.3和5.66mm,其中沙地蒸发量占主要部分.少量降水时,幼苗蒸腾速率明显呈现"午睡”现象,而充足降水则能消除"午睡”现象.相关分析结果表明,环境因子,如沙地含水率、太阳有效辐射、大气温度和饱和水汽压差,以及植物因素,如叶面积指数、叶片温度和气孔导度等,均能显著影响沙柳的蒸腾作用.

关键词: 模拟降水量, 毛乌素沙地, 沙柳幼苗, 蒸发蒸腾作用