长江三峡地区退化生态系统植物群落物种多样性特征

PLANT SPECIES DIVERSITY OF THE DEGRADED ECOSYSTEMS IN THE THREE GORGES REGION

以三峡地区退化生态系统植物群落样地资料为基础，研究了不同退化类型、不同退化程度植物群落的物种多样性特征，分析了植物群落物种多样性与人为干扰和演替的关系。结果表明：受干扰较轻的退化类型，群落物种多样性比自然生态系统高，受干扰较严重的退化类型，群落物种多样性比自然生态系统低。随着生态系统的退化，群落物种丰富度先升高后又逐渐降低。从不同层次来看，乔木层物种多样性逐步减低，灌木层和草本层物种多样性则表现出先升高后又逐渐降低。退化森林生态系统各层次的物种多样性表现为灌木层、草本层＞乔木层，和地带性生态系统常绿阔叶林的灌木层（包括乔木幼苗和幼树）＞乔木层＞草本层的格局有显著差别。若以空间代替时间，则表现出随着演替进程群落物种多样性升高后又降低。从群落各层次来看，乔木层随着演替进程物种多样性逐步升高，灌木层、草本层则先升高后又降低。

Plant species diversity of different types and different level of degraded ecosystems,and their correlation with human disturbance and succession were studied through field investigation The results showed that slightly degraded communities had a higher species diversity,while the serious degraded ones had a lower diversityIn the course of degradation,plant community richness slightly increased and then decreased.In respect of different layer, species diversity of tree layer,shrub layer and herb layer decreased with a slight increase in shrub layer and herb layer in the first phase.Species diversity of shrub layer and herb layer was larger than that of tree layer in the degraded forest types.This pattern was different from that for zonal evergreen broadleaf forest in which species diversity of shrub layer (including seedling and sapling) was large than that of tree layer.The specics diversily of herb layer was the smallest.If different place of different stage instead of time course was used,community species diversity could increase and then decrease in the succcession of communities.In the light of different layers,the species diversity of tree layer largly increased with succession,while those of shrub layer and herb layer increased first,and then decreased.