朝阳地区不同植被退化阶段划分及植物群落特征研究

Division of vegetation degradation stages and their characteristics of plant communities in Chaoyang

为研究朝阳地区的植被退化现状,提供退化植被恢复及生态工程建设的参考依据,该文采用聚类分析法,在对朝阳市5个县市区不同植被退化阶段的植物群落特征调查研究的基础上,依据植被生长指标划分出4个植被退化阶段,分别为未退化阶段、轻微退化阶段、轻度退化阶段和中度退化阶段。未退化阶段和轻微退化阶段的植物群落具有明显的乔木层,植被类型以天然次生混交林为主,立地条件较好的植物群落会出现山杨、白桦、椴树、落叶松、暴马丁香等树种,稍差些的主要以柞树、小叶白蜡、黄榆、油松、山杏、花曲柳等树种为主。轻度退化阶段和中度退化阶段的植物群落无明显的乔木层,植被类型以天然次生混交灌丛为主,乔木更新幼树混生于灌木层中。树种组成灌木主要以绣线菊、荆条、榛子、胡枝子为主,乔木更新幼树主要以黄榆、山杏、小叶白蜡、暴马丁香、花曲柳为主。不同植被退化阶段的植物群落,灌木和草本的生长差异不明显,尤其是草本层。未退化区和轻微退化区植被群落的显著差异在于乔木层整体的生长状态,最直观的区别在于乔木的密度和郁闭度,轻度退化区和中度退化区植物群落的显著差异在于灌木层的生长状态,最直观的区别在于灌木的盖度。

The clustering analysis method was adopted in this paper,and the vegetation characteristics of different stages of vegetation degeneration in five counties in Chaoyang City were investigated.On the basis of vegetation growth indicators,they were divided into four stages of vegetation degeneration,including non-degraded stage(L1),slight degradation stage(L2),mild degradation stage(L3)and moderate degradation stage(L4).The vegetation community of non-degraded stage and slight degradation stage had obvious tree layers,and the vegetation type were dominated by natural secondary mixed forests.In the plant community with better site conditions,there were Populus davidiana,Betula platyphylla,Tilia tuan,larch,Syringa reticulata var.mandshurica,et al.While with the worse site conditions,there were oak,Fraxinus sogdiana,Ulmus macrocarpa,Pinus tabulaeformis,prunus sibirica,Fraxinus rhynchophylla,et al.The vegetation community of mild degradation stage and moderate degradation stage had no obvious tree layers,and the vegetation type were dominated by natural secondary mixed shrubs,and the regeneration young trees intermixed in the shrub layer.In terms of the composition of tree species,the main shrubs were Spiraea salicifolia,Vitex negundo,Corylus heterophylla and Lespedeza davurica,and the main regeneration young trees were Ulmus macrocarpa,prunus sibirica,Fraxinus sogdiana,Syringa reticulata var.mandshurica,Fraxinus rhynchophylla,et al.Among different stages of vegetation degeneration,the differences of growth in shrub and grass were not obvious,especially in grass layer.The significant difference of vegetation community of non-degraded stage and slight degradation stage were the overall growth condition of tree layer,and the most obvious differences were stand density and canopy density of trees.The significant difference of vegetation community of mild degradation stage and moderate degradation stage were the growth condition of shrub layer,and the most obvious differences were coverage of shrubs.