Abstract: In this research, field surveys of species composition and vegetation community structure of 22 gullies in the hot-dry valley region of Yuanmou County in Yunnan Province were carried out using standard vegetation sampling methods to study the plant community structure in gullies with different activity levels. As the gully stability increased, the number of plant species also increased. Twenty-eight species of plants belonging to 28 genera of 12 families, were found in active gullies. Twenty-nine species of plants belonging to 29 genera of 16 families, were found in semi-stable gullies. Thirty-seven species of plants belonging to 35 genera of 15 families were discovered in stable gullies. Based on plant form, the gully vegetation communities could be divided into three layers (herb layer, shrub layer and tree layer) which varied with the activity level of the gullies. No tree layer was found in the active gullies. The dominant species in the herb layer was Heteropogon contortus, with Bothriochloa pertusa and Aristida adscensionis as sub-dominant species. The dominant species in the shrub layer was Dodonaea viscosa, with Leucaena leucocephala as the sub-dominant species. The dominant species of the tree layer was Azadirachta Indica, with Eucalyptus robusta as the sub-dominant species. As the gully stability increased, so also did the coverage of its vegetation community. The plant communities in gullies with differing activity levels were all dominated by perennial herbs and shrubs, with a smaller number of tree species of trees, in which the dominant species were the same and played similar roles in the plant communities. However, with increasing stability of gullies, the number and diversity of trees gradually increased. For active gullies, semi-stable gullies and stable gullies, the plant community similarities were comparatively similar in the herb layer, extremely similar in the shrub layer, and extremely different in the tree layer. As the stability of a gully changed, the tendency for the plant community matured without species change in the shrub layer was evident. However, for the herb layer and tree layer, as the gully stability increased with time the species composition of the vegetation community evolved. These results indicate that the activity status of a gully plays an important role in determining the community structure of the tree layers, while the community structure of the shrub layer was less affected by the activity status of the gully. In summary, an obvious difference in vegetation structure was evident between gullies with different activity status, and this information could provide a scientific basis for gully ecological restoration decisions and for formulation of future studies.

Key words: gully, community structure, important value, diversity index, community similarity, vegetation restoration