策勒绿洲前沿两种植物的水分生理生态特征

20 0 3年夏季 ,在策勒绿洲前沿地区同一生境条件下 ,研究了骆驼刺 (Alhagisparsifolia)、多枝柽柳(Tamarixramosissima)水势和蒸腾作用的日变化及其与环境因子的关系。结果表明 :在相同土壤水分条件下 ,多枝柽柳的水势低于骆驼刺的水势。多枝柽柳的蒸腾作用与得到充分水分供应的植物一致 ,而骆驼刺则表现为中午限制供水的植物类型。多枝柽柳和骆驼刺气孔导度的变化是影响蒸腾速率最主要的因子 ,环境因子中气温、大气相对湿度与蒸腾速率的相关性最显著 ;有效光合辐射与水势的相关性最高。大气相对湿度与水势呈正相关 ,与蒸腾速率呈负相关。从两种植物表现出的水势和蒸腾作用的特点看 ,多枝柽柳较骆驼刺更适应所处的生境条件

The Physiological and Ecological Characteristics of Moisture in Two Plant Species at the Foreland of Qira Oasis

Qira Oasis is located at the southern fringe of the Taklamakan Desert, the aridest region in northwest China, where the mean annual precipitation is less than 40 mm but the potential evaporation is as high as about 2 600 mm. The perennial Alhagi sparsifolia Shap. and Tamarix ramosissima Lebed. are dominant, which are the important endemic species in the foreland between vast desert and the Qira Oasis. In the same habitat, the daily course of transpiration and water potential in A. sparsifolia and T. ramosissma are studied in summer at the foreland of Qira Oasis, and the relationship between the plants and the environmental factors is analyzed. The results show that the water potential of T. ramosissma is lower than that of A. sparsifolia under the same soil moisture content. The transpiration of T. ramosissima accords with that of the plants which can get enough moisture supply, but the transpiration of A. sparsifolia is similar to that of the plants that the moisture supply is restricted at the noon. Change of the stomatal conductance is the most significant factor affecting the transpiration of both A. sparsifolia and T. ramosissima. In the environmental factors, the correlation between both air temperature and relative air humidity and the transpiration of T. ramosissima and A. sparsifolia is the most significant.