Exploring land-use legacy effects on taxonomic and functional diversity of woody plants in a rapidly urbanizing landscape

Abstract

Urban vegetation is influenced by prior land use due to the dynamic nature of urban landscape. However, limited information is available on how strongly the land-use legacy impacts the diversity of urban vegetation, especially in areas of rapid urbanization. This study quantified the land-use legacy effect on taxonomic and functional diversity of woody plants in Haikou, China. We collected data on land use, percentages of woody vegetation cover, and abundance of woody plants from 461 randomly distributed sample plots. The influence of land-use legacy was examined by analyzing the land-use history of sample plots and taxonomic and functional α- and β-diversity of woody plants. The relative importance of the land use and the percentage of woody vegetation cover on the diversity of woody plants were analyzed using the boosted regression tree model. The result showed that the land-use legacy effect caused significant divergence in taxonomic and functional diversity of woody plants and the effect was most obvious in sites where the lands were currently used as residential areas. Remnant trees, shrubs, and possibly shrubs growing from seed banks and roots contributed to this legacy effect. We also found that taxonomic and functional α-diversities of trees in a site were influenced by how frequent the land use of the place was changed and what type of land use that the place ended up with. Based on our findings, we recommend conservation programs in rapidly urbanizing regions give more attention to vegetation in residential areas and particularly species with low utilitarian value.