不同生境梭梭对降水变化的生理响应及形态调节

Physiological Response and Morphological Adjustment of Haloxylon ammodendron in Different Habitats against Precipitation Variation

以中亚荒漠关键种梭梭为研究对象,对比2006年生长季土壤水分状况和生长在沙土及黏土中梭梭对3个降水处理的生理响应与同化枝面积的累积变化,分析不同质地土壤生长的梭梭在生长季对降水变化的生理响应及其形态调节。结果表明,沙土中生长梭梭对降水响应明显,生长季同化枝水势较高,且不同降水处理下蒸腾速率和瞬时水分利用效率差异显著,同化枝形态调节幅度不大。黏土不利于降水入渗,梭梭同化枝水势、蒸腾速率和瞬时水分利用效率对降水变化的响应不敏感,同化枝面积和生长速率在不同降水处理间差异显著,同化枝脱落较早。生理响应与形态调节的综合研究表明,不同质地土壤生长的梭梭通过有效的同化枝形态调节保证了其在降水处理下稳定的光合碳同化作用。在全球气候变化的背景下,沙土更有利于梭梭的生长。

Haloxylon ammodendron,a native dominant desert shrub,was chosen as the study object,and the variation of soil moisture content,plant physiological response and branch biomass change in sandy soil and heavy textured soil under three precipitation treatments（no,natural and double precipitation,respectively） were monitored during the growing season in 2006.The similarity and difference of physiological response and morphological adjustment of H.ammodendron to precipitation treatment were analyzed.The results indicated that the branch water potential,transpiration and photosynthetic water-use efficiency of H.ammodendron in sandy soil differed significantly under three precipitation treatments,but these parameters of H.ammodendron in heavy-textured soil did not appear a high sensitivity to precipitation variation.Under the three precipitation treatments,the branch growth rate of H.ammodendron differed significantly in heavy textured soil,but not in sandy soil.The integrated analysis of physiological response and morphological adjustment indicated that biomass allocation,or morphological acclimation at individual plant scale maintained photosynthetic stability and the survival of H.ammodendron in different textured soils under different precipitation treatments.H.ammodendron in sandy soil will be favored over those in heavy-textured soil in the natural background of climatic change.