中文摘要：

在科尔沁阿古拉生态水文试验区沿着3条经线布设了19个50 m×50 m的自然植被样地，依据调查的12个生境因子及48种植物的重要值，选用多元回归树（MRT）和除趋势典范对应分析法（DCCA）对调查样地、主要科植物种、不同生活型植物种与生境因子的相应关系进行了探讨，并通过前向选择结合Monte Carlor检验，筛选出对植物群落分布格局产生显著影响的生境因子。结果表明：（1）采用MRT数量分类方法，将植被划分为4个群类型，与样地在DCCA二维排序图上的散布格局具有一致性，将4个群落分别命名为：狗尾草（Setaria viridis）＋沙米（Agriophyllum squarrosum）-差巴嘎蒿（Artemisia halodendron）群丛，大籽蒿（Artemisia sieversiana）＋花苜蓿（Medicago ruthenica）＋羊草（Leymus chinensis）群丛，叉分蓼（Polygonum divaricatum）-木岩黄芪（Hedysarum fruticosum）＋小叶锦鸡儿（Caragana microphylla）群丛，走茎灯心草（Juncus amplifolius）＋芦苇（Phragmites australis）群丛。（2） DCCA排序结果表明，菊科植物和禾本科植物在研究区的4个群落中均有分布，而豆科植物多出现在固定程度较好的沙丘群落中，随着沙丘固定程度的提高,植物种生活型演变过程为：一年生→一年生＋多年生→一年生＋多年生＋灌木、半灌木→一年生＋多年生；（3）对群落产生显著影响的生境因子主要有土壤电导率、黏粒含量、有机质含量和毛管上升含水率4个变量，DCCA排序图明显反映出排序轴的生态意义，第1轴从左到右突出反映了沙丘群落和草甸群落间断分布，主要梯度影响因子是土壤电导率和黏粒含量，第2轴反映了土壤有机质含量和毛管上升含水率对不同固定程度状态下沙丘群落的分布起决定性作用。

英文摘要：

Based on the 12 habitat factors and the importance value of 48 plant species surveyed, the relationships between environmental factors and vegetation patterns in the semiarid desertification area were explored. A research area of Agula Ecohydrological Experimental Station which is located in the southern Horqin Sandy Land in China was selected to set up 19 plots along three lines of longitude. The types of plant community, the plant of main families and the plant of different lifeforms in this region were investigated in relation to environmental factors using MRT and DCCA. In order to eliminate redundant environmental variables, the environmental factors which significantly influence plant community composition were chosen by forward selection and Monte Carlo tests. Results showed that： 1） The plant communities in this region could be divided into 4 types by MRT, which was in accordance with the spreaddimensional pattern on the DCCA ordination diagram. The four associations were Setaria viridis ＋ Agriophyllum squarrosum-Artemisia halodendron association, A. sieversiana ＋ Medicago ruthenica ＋ Leymus chinensis association, Polygonum divaricatum-Hedysarum fruticosum ＋ Caragana microphylla association, Juncus amplifolius＋ Phragmites australis association; 2） Results of DCCA ordination indicated that Compositae and grasses were distributed in four communities in the study area, while legumes were more likely to be found in the better fixed dunes. With the improvement in the level of fixed dunes, the evolutionary process of the life forms about species was： the annual herb→ the annual and perennial herb→ the annual and perennial herb ＋ shrubs, subshrub →the annual and perennial herb; 3） Four environmental variables were used in the species-environment correlation analysis. The first axis indicated that the dune community and the meadow community were discontinuously distributed, and the electrical conductivity and clay content o