塔克拉玛干绿洲外围胡杨林的水分特征研究

Characteristics of Water Status in Populus euphratica Outside the Oases in the Taklamkan Desert

塔克拉玛干沙漠南缘地区年均降水量不足50mm,胡杨在这一地区绿洲外围自然植被中占有重要地位.对塔克拉玛干沙漠绿洲外围胡杨林水分特征的研究表明,在生境地下水含量较稳定的条件下,胡杨林受到的水分胁迫程度不大,干旱胁迫未对胡杨林的持续存在构成主要威胁.胡杨的水分生理特点显示植物更加依靠稳定的水分供应来应对极端干旱的环境条件,并且在蒸腾作用中形成了细胞水平上的生理适应策略.因此,保持地下水的稳定是维持绿洲前沿天然胡杨林持续存在的关键因素.

In the extremely arid area of the southern Taklamakan Desert in Xinjiang, NW China, the mean annual precipitation is less than 50 mm. Outside the river oases in this region, Populus euphratica Oliv. is a dominant woody plant in indigenous vegetation. The water status of P. euphratica was studied in the southern Taklamakan Desert. The results showed that with the stable soil water content in habitat resulting from permanent ground water table, the water stress of P. euphratica was not severe and drought stress was not the main factor to threaten the long-term survive of P. euphratica. The characteristics of water status in P. euphratica indicated that the plant depended mainly on constant sufficient water supply to cope with the extremely drought environment at its growing sites. At the same time, this species developed its physiological adaptation at cell level in transpiration. Therefore, the key factor to guarantee a sustainable survival of P. euphratica in the peripheral area of the oases is to keep the groundwater table stable in different depths.