Species Composition And Diversity Of Plants In Rural Settlements Of Wuhan

Today, urbanization has becoming an inevitable tendency in most of the areas near big cities. The effects of urbanization had also been focused unprecedently. The rapid expansion of the main urban area facilitates the disappearance of rural settlements. People paid more and more attention to the completeness of the transformation of rural settlements, since the management of rural areas couldn't meet the standards of the modern cities. Some of the studies focus on the social problems and the mode of transformation of the rural settlements. However, there are still few studies on the rural ecosystems in China, especially in an ecological perspective. Evaluating the ecological values of urban plant communities would provide invaluable information for plant conservation plans.In this study, the species composition were examined at 32 villages in Wuhan.There were 477 species (varieties or forms) falling in 321 genera,133 families, in 279 plots scatted in 32 rural settlements ares. Speices in Poaceae, Compositae and Fagaceae are among the most frequent. Among which,356 species are native,83 species cultivated and 38 species invasive. Native plants belonged to 96 families,244 Genera. Poaceae is the top that has native species, which include 43 species.There are 70 genera,39 families, with the 9 species in Fagaceae as the richest family. The invasive species falled into 32 genera and 16 families, with the dominant family Compositae.The mean value of alpha diversity between different types of communities, soil types, habitats, and the types of human disturbance was compared. There are significant difference has been found between the diversity of trees and herbs in semi-natural and artificial communities, but not found from shrubs. Species richness are significantly different among the habitat types, especially for the herbs. Additionally, differences of richness in tree and herb species were significant among the 6 types of human disturbance.The packages fossil and vegan in R were employed to calculate the pairwised distances among the geographical distances and species relatedness for each paire of plots. A linear model has been build to examine the relationship between geographical distance and species relatedness in a distance decay context. The species dissimilarity increased while the geographical distance increased.A phylogenetic tree for each species appeared in the 279 plots was built using online software Phylomatic. The phylogenetic diversity(PD), Net Related Index (NRI) and Nearest Taxon Index was calculated using Phylocom. It is found that none significant linear relationship between NTI and species richness. However the NRI index was positively related with species richness. The species co-occurred in one plot tend to be distantly related while the plot has only a few species. As the number of species co-occurred in one plot increases, the relationship of species tend to be more nearer than random. NRI and NTI are not affected by the richness of cultivated species. However, NRI and NTI was positively correlated with the richness if invasive species. The species tend to be nearer than random as the number of invasive species increases.Remote rural settlements harbor the richest species richness, than in central city and urban areas, while the central city has the poorest species richness. There are significant differences between the three regions (central city, urban areas and remote rural settlements) for number of families, genera and species. It is concluded that the process of urbanization has negative effects on the plant communities.The relative frequency of each species were calculated and were divided into three groups:the native species, cultivated species and invasive species. Native species became more dominant from central city to remote rural settlements, possibly because of the increasing number of species. The urban area harbors the richest number of invasive species, possibly due to periodic weed elimination.The ratio of cultivated species constantly decreased as the from the central city to remote urban areas. Large number of ornamental species cultivated in central city and urban areas has led this high ratio.It is suggested that the native plant species should be first considered in the transformation process of rural settlements. So as stable plant communities could be reconstructed.The shrubs should be considered as ground cover in priority. An comprehensive checklist of plants were given for further application.