降雪对荒漠生物土壤结皮光合生理特性的影响

生物土壤结皮（BSC）广泛分布在干旱、半干旱区，对荒漠生态系统的稳定、平衡等具有重要意义。初步探讨了降雪量对腾格里沙漠东南缘藻类、地衣和藓类结皮叶绿素荧光参数、光合色素、丙二醛（MDA）及可溶性蛋白含量的影响。结果表明：结皮光合生理特性对降雪量的响应有显著差异。适量降雪激发3种结皮PSⅡ反应中心，引起光合色素、可溶性蛋白合成升高，MDA含量降低；过量降雪导致藻类和地衣结皮光合电子传递受阻，光合色素、可溶性蛋白合成减少，MDA含量升高，产生光抑制现象。适量冬季降雪对结皮具有一定的促进作用，而藓类结皮更能适应极端降雪环境，但相关分子机制还需深入研究。

Effects of Snow on the Photosynthetic Physiological Characteristics of Biological Soil Crusts in A Desert Region

Biological soil crusts (BSC) are widespread in arid and semi-arid regions, and play significant roles in ecosystem stability maintenance and ecological balance. With successional stages of BSC (algae, lichen and moss) in the southeastern fringe of the Tengger Desert as test objects, and studies preliminarily the effects of snow on chlorophyll fluorescence parameters, photosynthetic pigments, malondialdehyde (MDA), and soluble protein of different types of crusts. Results show that different BSC species exhibit different responses to snow on photosynthetic physiological characteristics. A moderate amount of snow stimulates photosystem Ⅱ reaction center, and increases contents of photosynthetic pigments and soluble protein, decrease MDA content, while excess amount of snow prevents photosynthetic electron transport of algae and lichen crusts, and photosynthetic pigments contents and soluble protein synthesis decreases, MDA content increases, which cause photoinhibition. Our study indicates a moderate amount of winter snow is favorable to BSC at the photosynthetic physiological level, while moss crusts are more suitable to excess amount of snow, its relative molecular mechanisms still need further research.