腾格里沙漠固定沙丘结皮层藓类植物的生态功能及与土壤环境因子的关系

Ecological Function of Mosses in Biotic Crusts on Fixed Dunes on Tengger Desert and Its Relation with Soil Factors

通过1998—2001年的野外调查,沙坡头地区固定沙丘结皮层藓类植物共3科、11属、24种,新发现 8 个本地区新记录种。人工固定沙丘仅分布有7种藓类,而自然固定沙丘包括了所有的 24 种藓类,具有较高的物种多样性,构成了复杂的苔藓植物群落。沿坡向随高度的上升,藓类植物的盖度减少,而藻类植物的盖度却有上升的趋势。自然固定沙丘藓类植物盖度明显小于围封的人工固定沙丘。人工固定沙丘随着固定年限的增加,藓类植物的生物量明显增高,不同种类藓类植物的生物量明显不同,综合盖度因素,真藓拥有该地区最大的生物量。不同类型、不同种类的藓类植物结皮厚度和株高之间都存在显著的相关性(P<0 01)。不同固定沙丘藓类结皮土壤的总盐量、阴、阳离子总量都明显高于藻结皮和流沙,苔藓结皮中苔藓植物体内Mg/Ca率在0 50~0 98之间,结皮土壤Ca2+含量明显高于其他3种离子,Na+、K+ 离子含量较少。苔藓植物生物量与土壤磷、土壤有机质呈明显正相关(P<0 05),土壤pH值与土壤磷含量和苔藓植物生物量呈显著负相关(P 分别为<0 01 和<0 05),表明高的 pH值显著影响土壤磷含量和植物生物量。磷含量还与氮含量显著相关(P<0 05),充分表明磷是荒漠生态系统苔藓植物生长发育首要的限制因子。藓类结皮土壤中的有机质、全磷、全氮、速磷。

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 Ca^(2+) 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%.