塔克拉玛干沙漠南缘风沙活动十分频繁,风蚀和沙埋是该地区自然植被生长发育的重要影响因子。该文以塔克拉玛干沙漠南缘策勒绿洲-沙漠过渡带为研究区,以该区域主要建群种植物骆驼刺(Alhagi sparsifolia)为研究对象,对一次强沙尘天气过后沙丘表面5种不同风蚀沙埋状况的骆驼刺植物进行标定(包括10 cm风蚀、5 cm风蚀、不蚀不积、10 cm沙埋、30 cm沙埋),天晴后测定其叶水势、叶片含水量、光合参数和叶绿素荧光等参数,分析研究自然环境条件下风蚀和沙埋对骆驼刺水分和光合作用的影响。结果表明:(1)风蚀显著降低了骆驼刺叶水势和叶片含水量,进而导致植物气孔导度降低,并引起植物光合速率和蒸腾速率的下降。风蚀的植物水分利用效率低于沙埋,特别是在10 cm风蚀深度明显降低。(2)沙埋增加了骆驼刺的叶水势、叶片含水量和气孔导度,并引起植物光合速率和蒸腾速率的上升,水分利用效率也得到提升。(3)风蚀条件下骆驼刺所受胁迫增加,但可以通过增加活性反应中心的数量和光化学效率来抵消胁迫造成的不利影响。沙埋条件下骆驼刺受胁迫减轻,反应中心吸收的光能和用于光化学反应的能量随着沙埋程度增加而减小,这是骆驼刺适应风沙环境的一种生存策略。(4)与5 cm风蚀以及10 cm沙埋相比,10 cm风蚀显著抑制骆驼刺的生长,30 cm沙埋则会显著促进骆驼刺的生长。
Aims The objectives of this study were to investigate the effects of disturbance through wind erosion and sand burial on water relations and photosynthesis in Alhagi sparsifolia, and to determine the best habitat for the growth of A. sparsifolia in the southern edge of the Taklimakan Desert. 〈br〉 Methods We set up five treatments, including wind erosion depth of 10 cm, wind erosion depth of 5 cm, control, sand burial depth of 10 cm, and sand burial depth of 30 cm. Measurements were made on the concentration of photosynthetic pigments, chlorophyll fluorescence parameters, leaf water potential, and leaf water content in A. sparsifolia under different treatments on a sunny day. 〈br〉 Important findings Leaf water potential and leaf water content in A. sparsifolia m significantly decreased fol-lowing the wind erosion treatments, thereby causing a reduction in the stomatal conductance, which in turn re-sulted in declining photosynthetic rate and transpiration rate. The water use efficiency in plants under the wind erosion treatments was lower than that under the sand burial condition, especially in the treatment of wind erosion depth of 10 cm. In addition, leaf water potential and leaf water content in A. sparsifolia were higher in the sand burial treatments than in the wind erosion treatments, which were associated with higher values of stomatal con-ductance, photosynthetic rate, transpiration rate, and water use efficiency. The maximum photochemical efficiency (Fv/Fm) in A. sparsifolia was suppressed under the wind erosion treatments, indicating increased stress suffered by the plants. However, A. sparsifolia may resist the adverse effects of wind erosion through increases in the number of active reaction centers and photochemical efficiency. The Fv/Fm in A. sparsifolia was higher under the sand burial treatments, indicating that the stress of A. sparsifolia suffered was alleviated. The absorption of light quantum yield and energy used for the photochemical reaction in the reaction center decre