呼伦贝尔沙质草甸草原洼地植物群落变化分析

选择呼伦贝尔沙质草甸草原上的干洼地,采用系统取样方法对不同微地貌部位的植物群落变化进行研究。发现,草原区微地貌变化对生境异质性的控制作用明显。在洼地中旱生植物和旱生植物占优势,中旱生植物在阴(N)坡和下坡位或坡底占优势,旱生植物在阳(S)坡最占优势。下坡位或坡底的多年生植物比例最高,其次是阴(N)坡和中坡位,上坡位和阳(S)坡最少。洼地内出现了12个不同类型的群落。同一坡向的植被覆盖度、地上生物量、草层高度呈现下坡位＞中坡位＞上坡位的趋势。主要物种的重要值波动很大,表明洼地内的地形因子分配不均匀。SW上坡位植物群落特征各项指标均出现低值,导致局部恶劣环境的微地貌产出部位,与风蚀坑集中分布区耦合。表明SW坡上部风蚀沙漠化的高发生率与该微地貌部位植被发育差有关。

Analysis on Plant Communities in a Depression in Hulunbuir Sandy Meadow Grassland, Inner Mongolia, China

A study was carried out on the relationship between the changes of micro-relief and the changes of plant communities as well as their spatial distribution patterns, by systematic sampling in a dry depression and its adjacent flat background grassland in the Hulunbuir sandy meadow grassland, Inner Mongolia, China. It was discovered that the changes of micro-relief has a great influence on the variety, composition, and the distribution pattern of plant communities in the depression. There are significant differences about the species composition, the community biotype and ecotype. Heterogeneity of the dominant species and sub-dominant species in different micro-relief were also observed. Plant community characteristics of coverage, ground biomass, and height were high on lower slopes, medium on the middle of slopes, and low on upper slopes. The important value differentiation of dominant specie at different places on slopes facing different directions was also significant. Overall status of plant community on upper SW slope was the poorest, compared with that on the depression and on background grasslands, coinciding with the mass occurrence of blowouts, which indicated that the poorness of vegetation coverage should be an important reason for the mass development of sandy grassland blowouts on upper SW slope in Hulunbuir sandy meadow grasslands.