摘要:若尔盖高原沼泽区土壤沙化过程中植物群落的变化及其成因机制是亟待解决的区域关键科学问题之一。在若尔盖高原红原县沙化沼泽区，研究了土壤沙化梯度上植物群落种类组成、物种多样性、地上生物量的变化及其与土壤湿度、容重和孔隙度的关系。随着土壤沙化程度增加，群落特征种组替代顺序为华扁穗草（Blysmus sinocompressus）种组→高山嵩草（Kobresia pygmaea）种组→四川嵩草（K.setchwanensi）种组→黑褐穗苔草（Carex atrofusca subsp.minor）种组→粗壮嵩草（Kobresia robusta）种组；植物种数（单位样方物种丰富度和总种数）和地上生物量均表现为单峰变化格局，但植物种数峰值出现在极轻度沙化的高山嵩草群落，地上生物量峰值出现在中度沙化的四川嵩草-黑褐穗苔草群落；β多样性表现为"U"型变化格局，最高值出现在未沙化的华扁穗草群落，最低值出现在极轻度沙化的高山嵩草群落；土壤湿度对植物种多度影响最大，可解释总方差的24.8%，其次为土壤容重，可解释总方差的1.4%；沙化过程中土壤湿度是影响植物群落生态分布和种类构成的关键因素之一，尤其影响群落特征种的多度和分布。粗壮嵩草可考虑作为沙化土地植被恢复的先锋物种。



Abstract:The vegetation community change and associated mechanism is one of the pressingly key scientific issues during soil desertification in the swamp area of the Zoigê plateau. Along soil desertification gradients, changes of species composition, species diversity and aboveground biomass and their relation to soil physical properties, i.e. soil moisture, volume weight and porosity, were studied in the desertified swamp area, Hongyuan County, the Zoigê plateau. As the increasing of the degree of soil desertification, the replacement order of community characteristic species group was Blysmus sinocompressus species group→Kobresia pygmaea species group→K. setchwanensi species group→Carex atrofusca subsp. minor species group→Kobresia robusta species group. Both the number of plant species (species richness per quadrate and total number of species) and above-ground biomass showed unimodal patterns. The highest number of plant species occurred in K. pygmaea community with extremely mild desertification, whereas the highest value of above-ground biomass occurred in K. setchwanensis-Carex atrofusca subsp. minor community with moderate desertification. The β diversity showed U-shaped pattern, which was the highest in Blysmus sinocompressus community with non-desertification, whereas the lowest in Kobresia pygmaea community with extremely mild desertification. Soil moisture was most correlated with the variation of plant abundance and explained 24.8% of total variance, followed by soil volume weight and explained 1.4%. Soil moisture was considered a key factor in regulating the ecological distribution and species assemblage of plant community during the process of desertification, especially for the abundance and distribution of characteristic species. K. robusta was considered a pioneer species of vegetation restoration in desertificated land in the Zoigê plateau.





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