呼伦贝尔退化草地植被演替特征研究

由于气候环境条件的变化和人类长期不合理的草地利用方式,致使呼伦贝尔草原退化、沙漠化趋势加剧,草地的退化严重威胁着当地的生态环境,制约着畜牧业的发展。对草甸草原、典型草原和沙地植被三种草地类型的植被退化演替特征研究结果表明:随着草地退化(沙化)程度加大,群落结构与多样性逐渐丧失,草层高度、植被盖度、株丛密度、地上部生物量等,都呈现不同程度的递减趋势,草地退化过程中,群落物种组成逐渐单一,数量逐渐减少,物种组成发生显著的变化。未退化草地以禾本科植物占主导地位,随着退化程度的加大,退化指示类的菊科植物的重要地位得到提升,中度退化阶段蔷薇科植物不断增加,并占据优势地位,重度退化阶段,多以耐践踏的蔷薇科植物和小型禾草为优势种,其中重度沙化草地,多年生植物几乎全部消失,而被一年生植物替代。

A Study on Vegetation Succession of Degradation Grassland in Hulunbeier Steppe

Resent years,because of the influences of nature factors and human activities,the eco-environment of the Hulunbeier steppe was gradually worsen.Grassland degradation seriously threaded to the local ecological environment,which restricted the development of husbandry.This study was conducted on the mechanisms and characters of vegetation successions with the degradation or desertification of three types of grasslands.Result showed that vegetation degradation of grassland was a process of decrease of species quantity,simplification of community structure,lose of diversity,the height of plants,percent plant cover,above-ground biomass were all correspondingly showed to decrease with increased of degradation levels.Graminoids played main roles at the normal grassland.While the importance values of compositaes were increased and were become dominant plants at lightly degradation levels,and at moderate degradation levels those of Rosaceaes significantly increased.Resistance trampling rosaceae and small Graminoids tended to became the main dominant species at extreme degradation levels,especially at the extreme desertification grassland the perennial herbs almost disappeared and were replaced by annuals.