古尔班通古特沙漠生境对植物群落格局的影响

Impact of Ecoenvironment on Vegetation Community Pattern in Gurbantunggut Desert

沿87°37′09″～88°24′04″E纵穿古尔班通古特沙漠,对44°14′04″～45°41′52″N的范围进行11个样地的地貌景观调查、植被分布参数采集和土壤取样.研究区统计到的植物种数占古尔班通古特沙漠文献资料中植物种数的1/3,出现的植物群落构建了该沙漠大面积成片分布的荒漠植被景观.调查发现,随着宏观生境的空间变化,植物群落作相应的演替.在此基础上,利用因子分析(PCA)和相关分析(CA)查明了沙漠风沙土理化属性,如土壤养分、盐分、水分、碱性(pH)等微生境的异质性仅对沙漠植被草本层片的多样性(PIE 草)产生显著影响.同时,这些微生境因相互拮抗使沙漠环境处于暂时的脆弱平衡之中.

Vegetation investigation and soil sampling of 14 sites, across the Gurbantunggut Desert along the range of 87o37'09'-88o24'04'E and in the range of 44o14'04'-45o41'52'N, were carried out. Eight species of low tree and shrubs, 5 of perennial herbs, 8 of annual plants, 48 of ephemeral and ephemeroid plants were recorded. These species of the plants occupy 1/3 species of Gurbantunggut Desert plant indices and their communities form vast patches of desert vegetation with great landscape significance. In the investigation we found that the vegetation communities are accordingly succeeded with the spacial variation of macro-ecoenvironment. On the basis of counting the frequency and important values, we chose Sinpson dominance index (C) and Herlbert diversity index (PIE) to describe the composition and structure characteristics of tree-shrub and herb synusiae. Using Principal Component Analysis (PCA) and Correlation Analysis (CA) we found that the micro-ecoenvironment heterogeneity of aeolian soil physio-chemical properties, such as soil nutrient, soil moisture, soil salt, pH, etc., only exerts significant impact on the diversity of herb synusia (PIEherb), with a negative correlation. Meanwhile, the micro-ecoenvironments, which take a form of antagonistic interaction, have composed a fragile equilibrium of the desert environment. In case this equilibrium is disturbed by artificial and natural factors, the ecological distribution pattern of Gurbantunggut Desert would change.