中文摘要：

对黄土高原丘陵沟壑区不同立地条件下的达乌里胡枝子群落水分特征及生物量进行了研究.结果表明：（1）不同立地下的达乌里胡枝子蒸腾日变化均呈单峰型,上午呈上升趋势,于13：00达到峰值,之后均呈不同程度下降趋势.（2）不同立地达乌里胡枝子群落0-200 cm土层平均含水量为阴坡12.34%,半阳坡11.29%,半阴坡11.15%,阳坡8.96%.不同立地达乌里胡枝子叶片相对含水量和饱和亏与各立地土壤含水量关系密切.（3）不同立地下各个时期的达乌里胡枝子群落的地上生物量表现为阴坡〉半阴坡〉半阳坡〉阳坡,地下生物量则表现为阳坡（447.39 g/m^2）〉半阳坡（409.12 g/m^2）〉半阴坡（344.92 g/m^2）〉阴坡（217.01 g/m^2）.可见,达乌里胡枝子群落的水分生理特性及生物量的积累与立地条件密切相关.

英文摘要：

This paper studied the characteristics of water physiological ecology and community biomass of Lespedeza davurica under four different habitats of the Loess Plateau in North Shaanxi. The typical habitats were classified with Sunny, Semi-sunny, Shade, Semi-shade. The results showed that the daily transpiration intensity of Lespedeza davurica changed into the unimodal curve in all four habitats. The curves are stronger in the morning and reached the peak at 13：00, during the afternoon, these values of transpiration all reduced in different extents. The mean water content in 0-200 cm soil layer was 12. 34% （Shade）, 11.29 % （Semi-sunny）, 11.15 G （ Semi-shade）, 8.96 G （ Sunny）, respectively. Remarkable relationships were found 5etween leaf RWC,WSD and soil water content. The aboveground biomass of Lespedeza davurica in different stage was in order of Shade〉Semi-shade〉Semi-sunny〉Sunny, but the root biomass was in order of Sunny（447.39 g/m^2）〉Semi-sunny（409. 12 g/m^2 ）〉Semi shade（344.92 g/m^2 ）〉Shade（217.01 g/m^2 ）.There is a close relationship between the site type and the eco physiology character such as the water using and biomass of Lespedeza davurica.