Impervious surface area is a key predictor for urban plant diversity in a city undergone rapid urbanization.

Urban biodiversity has increasingly been recognized by the scientific community and environmental policymakers as a part of conservation efforts worldwide. However, most studies on urban biodiversity focus on cities in developed countries. An information gap exists for urban biodiversity of cities in developing countries. Here we focused on variability in plant diversity, a major component of biodiversity, in a Chinese city that has undergone rapid urbanization in recent time. The influence of urbanization was determined by comparing plant diversity and proportion of exotic/endemic plant species with the intensity of urbanization across the study area. We used percentage of total impervious surface area (PTIA) as an indicator of urbanization intensity, ranging from 5% to 95% across the study area. In the study area, a total of 321 plant species was recorded, totaling 83 trees, 113 shrubs and 125 herbs. Plant diversity, measured by number of plant taxa and other indices, was driven by PTIA; an increase in PTIA reduced plant diversity. In addition, the ratio of exotic to endemic plant species increased as PTIA increased. Among the exotic species, most of the tree and shrub species were purposely introduced. Above 40% PTIA, plant diversity decreased sharply and the proportion of exotic species rose. As a valuable predictor of urban biodiversity, PTIA can thus be used as a key criterion for urban planning to ameliorate urban biodiversity. Further, our findings extend current understanding of urban biodiversity for cities in developing countries.