新疆古尔班通古特沙漠生物结皮绿藻研究

Study on Chlorophytes of Microbiotic Crusts in the Gurbantonggut Desert,Xinjiang

通过对古尔班通古特沙漠中39块样地253份生物结皮土样的分析,研究了古尔班通古特沙漠中绿藻的区系组成、生态分布特点和结皮不同发育阶段绿藻的种类组成的动态变化。结果表明:该沙漠中有绿藻门植物10科14属26种,其中以单细胞种类占优势;绿藻在该沙漠不同地貌部位的分布,以背风坡的种数最多(9种),迎风坡、丘间低地和垄顶逐渐降低;在结皮的不同层次中,绿藻主要分布在结皮层,而在结皮层以下种类很少;在生物结皮的几个不同发育阶段中,绿藻的物种多样性差别不大,其种类组成略有差别。

The Gurbantonggut Desert （44°11＇-46°20＇N, 84°31＇-90°00＇E） is located in the central area of the Junggar Basin in north Xinjiang, it is the largest fixed and semi-fixed desert in China, and its area is about 4.88×10^4 km^2. In the hinterland of the desert, dune-chains are dominant, and their area occupies about 80 % of the fixed and semi-fixed desert. Annual precipitation in the desert is about 150 mm and only 70-100 mm in the hinterland of the desert; the annual temperature varies in a range of 6-10℃, the extremely maximum temperature is over 40℃, and the annual accumulated temperature ≥10℃ is as high as 3000-5000℃ ; the relative humidity varies in a range of 50%-60% in average and below 45% during the period from May to August. In this paper, chlorophytes collected from 253 microbiotic crust samples in the Gurbantonggut Desert are studied based on field investigation and microscopical observation in laboratory. The flora composition and ecological distribution of chlorophytes in the desert and the change of species composition of chlorophytes at different developing stages of microbiotic crusts are preliminarily analyzed. The results show that there are 26 species belonging to 14 genera and 10 families of chlorophytes, in which unicellular chlorophytes are dominant. There are some differences in distribution of chlorophytes at different dune positions. The taxa of chlorophytes at lee- ward of dunes are the most, and they reduce gradually at windward, inter-dune lowlands and top of dunes. Chlorophytes are mainly distributed within microbiotic crusts, and the taxa of chlorophytes decrease obviously under microbiotic crusts. The change of the species diversity of chlorophytes at the different developing stages of microbiotic crusts is not so significant, but there are some differences in species composition. Chlorococcum humicola, Chlorella vulgaris, Chlamydomonas ovalis and Chlamydomonas sp. exist nearly at all the developing stages of microbiotic crusts. At several earlier stages of microbiotic crusts there are coccal chlorophytes and filamentous ones. When moss crusts forme, filamentous chlorophytes, such as Microspora and Ulothrix, disappear.