Vegetation and plant species richness on six pre-islands, the Three Gorges Reservoir
三峡水库岛屿成岛前的植被特征与物种丰富度

We studied the vegetation on six pre-islands (land areas which will become islands as a result of flooding) in the Three Gorges Reservoir with a focus on plant species richness for each community. A total of 28 community types were found on these pre-islands,comprising of 12 hassocks,7 shrubs,and 9 forests. The results showed that natural vegetation was characterized by intense degradation,implied low vegetation cov-erage,restricted distribution of forests,low community diversity and high ratio of ruderal community types. The species richness of wild vascular plants on the six pre-islands was 126,157,175,189,242,and 254,re-spectively. The average species richness was 42.9 for forest,15.96 for shrub,and 17.89 for hassock commu-nities. In all hassock communities,species richness was high in ruderals but was low in typical degraded hassocks. Species richness was generally low in all shrub communities. In the process of secondary succes-sion from conifer-broadleaf forest to broadleaf forest,species richness fluctuated remarkably. Exotic plants significantly impacted the landscape,resulting in degradation of the natural vegetation. These pre-islands are valuable for scientific research,we suggest establishing some nature reserves on them.