梭梭(Haloxylon ammodendron)生理与个体用水策略对降水改变的响应

随着全球变化的加剧，降水改变正导致荒漠生态系统中植物用水策略的适应性变化；对降水变化响应的种间差异性影响着荒漠植物群落组成。研究将生理生态与个体形态尺度相结合，调查中亚荒漠关键种梭梭Haloxylon ammodendron对降水变化导致的自然生境中水分条件改变的响应与适应。实验于2005年生长期开展，在古尔班通古特沙漠南缘原始盐生旱生荒漠中设置3个降水梯度（自然、双倍和无降水）；观测并比较不同降水条件下光合作用、蒸腾作用、叶水势、水分利用效率、地上生物量累积和根系分布的变化。结果表明，梭梭主要利用降水形成的浅层土壤水维持生存；有效的形态调节和较强的气孔控制是其维持光合能力以及适应降水变化的主要机制；降水增多对其产生正效应，预示着梭梭可能在未来种间竞争和群落演替中占有优势。

Ecophysiological response and morphological adjustment of Haloxylonammodendron towards variation in summer precipitation

As part of global climate change,variation in precipitation in arid ecosystems is leading to plant adaptation in water use strategies;significant interspecific differences in responses will change the plant composition of desert communities.This integrated study on the ecophysiological and individual morphological scales investigated the response,acclimation,and adaptation of a native dominant desert shrub,Haloxylon ammodendron,to variation in water conditions.The experiments were carried out under three manipulated precipitation treatments(natural,double and no precipitation),in its original habitat on the southern periphery of Gurbantonggut Desert,during the growing season in 2005.Changes in its photosynthesis,transpiration,leaf water potential,water use efficiency,above-ground biomass accumulation,and root distribution were examined and compared under the contrasting precipitation treatments.The results indicate that its efficient morphological adjustment,combined with strong stomatal control,contributes to its maintenance of photosynthesis and acclimation to variation in precipitation.On account of its positive responses to increased precipitation,H.ammodendron is predicted to succeed in interspecific competition in a future,moister habitat.