中文摘要：

灌丛和生物土壤结皮镶嵌分布是古尔班通古特沙漠一种重要的地表覆被类型,灌丛的存在不仅为小型动物提供了庇护场所,也为隐花植物及部分草本植物创造了良好的生存条件。然而在初冬时期移除灌丛是否会影响这些隐花植物的越冬及生长还不得而知。该研究通过模拟放牧及鼠害,移除50%双穗麻黄（Ephedra distachya）灌丛、移除全部双穗麻黄灌丛及自然对照,测定齿肋赤藓（Syntrichia caninervis）植株脯氨酸、可溶性糖和可溶性蛋白含量,以及丙二醛（MDA）含量和超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）3种抗氧化酶活性,并测定原位光化学效率,探讨初冬灌丛丧失对荒漠藓类植物越冬的影响。结果表明,在积雪期3种处理下齿肋赤藓的游离脯氨酸和可溶性糖含量之间差异并不显著,但去灌丛后其MDA含量、POD、SOD和CAT 3种抗氧化酶活性均显著高于自然灌丛下齿肋赤藓的相关生理指标。即使是在融雪期,去灌丛下齿肋赤藓的可溶性糖含量及POD和CAT活性仍显著高于自然灌丛,而可溶性蛋白明显较低,这可能是由于灌丛的丧失造成的温度波动加剧了冬季低温对藓类植物的伤害。灌丛的部分移除（50%）对齿肋赤藓的生理生化特性影响不显著,就积雪融化期叶绿素荧光活性持续时间而言,与自然灌丛和移除50%灌丛相比,完全移除灌丛的齿肋赤藓植株叶绿素荧光活性持续时间显著缩短。这可能是由于灌丛移除导致其UV-B辐射增加及＂湿岛效应＂消失所致,UV-B辐射的增加加剧了对植物的伤害,而春季融雪期保水能力的下降也是其叶绿素荧光活性时间缩短的重要原因。

英文摘要：

Aims Patchily distributed biological soil crusts and shrubs is one of the main vegetation cover types in Gurbantünggüt desert. The existence of shrubs in desert areas serves not only as a shelter for small animals, but also a good living condition for cryptogams and some herbs. Syntrichia caninervis, a dominant moss species in Gurbantünggüt desert, is patchily distributed under shrub canopy and open spaces between vascular plants. To our knowledge, the impacts of the removal of shrub canopy on physiological and biochemical characteristics of S. caninervis during the winter is still unknown. Methods We simulated grazing of animals on Ephedra distachya at various rates（shrubs left intact, 50% shrubs removed, and shrubs removed completely） by cutting different percent of above-ground shoots of E. distachya. The shoot water content, chlorophyll fluorescence, proline content, soluble sugar content, soluble protein content, malonyldialdehyde（MDA） content, peroxidase（POD） and superoxide dismutase（SOD） activity were compared. Important findings The results show that, as for proline and soluble sugar contents of tested S. caninervis, there were no significant differences among three treatments of shrub canopy. However, the MDA content, and the activities of POD, SOD, CAT were significantly higher than nature shrubs in snow cover periods. During ——snow-melting periods, soil moisture and temperature did not served as limiting factors on the growth of S. caninervis. The soluble sugar content, and the activities of POD, CAT with shrub removal were significantly higher than shrubs left intact. This may indicate that the decline of the function of maintaining constant soil temperature due to shrub canopy increased the damage of temperature on moss plants. In addition, as for physiological and biochemical characteristics, there were no significant differences between two treatments of 50% shrub canopy and shrub canopy left intact. In snow covered periods and snow melting periods, the MDA content, the acti