松嫩平原南部植物群落的分类和排序

 松嫩平原南部的气候具有温带半湿润大陆性的特点。地带性植被为草甸草原。由于小地形起伏，土壤盐碱和水分含量有差异，影响植物的分布和组合，形成不同的群落。本文采用定性和定量相结合的方法，对该地区的植物群落进行了分类和排序，划分了11个群落类型，归为5类生态组合。通过样地和群落的排序说明植被既是连续的，又是间断的，同时明显看出植物群落随着土壤盐碱和水分含量的变化。

CLASSIFICATION AND ORDINATION OF PLANT COMMUNITIES IN THE SOUTH OF SONG-NEN PLAIN

In the south of the Song-Nen plain there is a temperate semimoist continental climate. The zonal vegetation in this region is meadow steppe. The distribution and combination of plants appear to be controlled mainly by the edaphic condition.Using qualitative and quantitative analyses, the vegetation can be divided into 11 communities. Based on ordination and biotope analyses, the 11 communities may be grouped into 5 ecological combinations: (1) The salt-alkali tolerant and hygrophilous combination, including the Sueada corniculata, the Sueada glauca and the Puccinellia tenuiflora communities; (2)The slightly salt-alkali tolerant and mesophilous combination, including the Leymus chinensis community; (3) The moisteutrophilous combination, including the Calamagrostis-Leymus, the Leymus-Potentilla and the Leymus-Hemarthria communities; (4) The Stipa baicalensis community on drainage rich soil; (5) The ammophilousxerophilous plant combination, including the Stipa grandis-Filifolium, the S. grandis and the Ulmus communities.As a example, a 2-dimensional ordination of 23 releves shows that the vegetation in the field is a mixture in varying proportions of continuity, and discontinuity In 2-dimensional ordination, the communities may be plotted according to the axes related to the saline content and alkalization of soil as well as soil moisture gradients in ordination field. The positions on each axis and the distance values between communities can quantitatively reflect the difference and relationship between communities.