关键词: 腾格里沙漠, 固定沙丘, 生物结皮, 苔藓植物, 土壤理化性质

Abstract: Mosses of three families, eleven genera and twenty-four species were found in the soil crusts of fixed dunes in the Shapotou region during several years of studying in fields, among which one genus and eight species were newly recorded in this region. The moss Acaulon C. M. was a newly recorded genus, and Crossidium crassinerve (De Not.) Jur. and Acaulon muticum (Hedw.) C. M. were two newly recorded species in China. Of all the genera, Pottiaceae of nine ones accounts for 81.82% of all species, Didymodon of six ones, 25%. Only seven moss species distributed in artificial-fixed dunes, whereas there were altogether twenty-four moss species in natural fixed dunes, which had high species diversity and constituted complex mosses communities in this region. The research revealed that the coverage of mosses decreased, while the coverage of the algae increased with gradient ascending. The coverage of mosses in natural fixed dunes was significantly less than that in enclosed artificial-fixed dunes. The biomass of the same moss species remarkably increased over time after re-vegetating in dunes. Different moss species had distinctive biomass in artificial-fixed dunes: the biomass of D. vinealis had a high proportion, but in consideration of the total coverage, the biomass of Bryum argenteum was the highest in the region; others had small coverage and biomass, but they played a very important role in maintaining soil stability and species diversity and in promoting micro-environmental evolvement. There were remarkably correlated relationships between the thickness and the height of different species with types of mosses (P < 0.01). The total amount of salinity, cation and anion were higher in different types of moss soil crusts than that in alga soil crusts and shifting sand. The Mg/Ca ratio was higher in plants than in soils. The Ca²⁺ content in soil crust was significantly higher, while Na⁺ and K⁺ content was the lowest in all cations. There were positive correlated relationships between the biomass of plants with P content and organic matter in soil (P < 0.05), and negative between soil pH with P content in soil and biomass in plants (respectively, (P < 0.01), P < 0.05), P content was also relative to N content (P < 0.05), which all indicated P content was one of the principal factors for moss growth in this region. In moss crust, organic matter, total N, total P, rapidly available N and rapidly available P contents were also higher than those in alga crusts, especially organic matter content in moss crust was over 1%. It was significantly important to maintain soil stability and to promote the establishment and reproduction of vascular plants in such a region where the organic matter was less than 1%.

Key words: Tengger Desert, fixed dune, biotic crust, mosses, soil physical and chemical characteristics