中文摘要：

利用Dynamax茎流测量系统,于2006年对科尔沁沙地一处20年生樟子松和小叶锦鸡儿人工混交林的液流动态进行监测。在液流测定的基础上,分别选择边材面积和叶面积为纯量进行尺度扩展来推算樟子松和小叶锦鸡儿林分蒸腾耗水量,分析林分蒸腾耗水量与沙地水分动态关系。结果表明：植物蒸腾耗水量的大小与太阳有效辐射和水蒸气压亏缺显著相关;在土壤水分严重匮缺的月份,樟子松日蒸腾耗水量呈现明显的下降趋势,变化范围为0.21~1.17 mm/d,平均0.81 mm/d;小叶锦鸡儿在低土壤含水量条件下对水分利用能力较强,表现出良好的耐旱性和稳定性,其蒸腾耗水的变化范围为0.51~2.79 mm/d,平均1.98 mm/d;8月份樟子松和小叶锦鸡儿蒸腾耗水量为86.5 mm,是同期降水的137.7%,水分条件是限制人工林存活状况的最主要因素。

英文摘要：

Sap flow rates were determined using sap flow methods in August, 2006 from a 20-year-old mixed plantation of Pinus sylvestris var. mongolica and Caragana microphylla at a sandy site located in the Horqin Region of northeastern China. Sap flow rates were then used to estimate transpiration of individual trees based on their sapwood areas and leaf areas. Furthermore, the relationship between water use and soil moisture dynamics was also analyzed. The results showed that variations in transpirations of both tree species were significantly related to the changes in photosynthetically active radiation and vapor pressure deficit. The transpiration rates for P. sylvestris var. mongolica showed a declining trend over the study period, ranging from0.21 to 1.17 mm per day with an average value of 0.81 mm per day. The transpiration from C. microphylla was relatively high and stable in semi-arid environment, and its daily transpiration values were 0.51-2.79 mm per day, with an average of 1.98 mm per day. The total transpiration from the mixed forest in August amounted to 86.5 mm, which represented 137.7% of the precipitation over the same period.