Socioeconomic Factors And Green Space Management Influence Plant Diversity Pattern Along Urban-rural Gradient In Shanghai,China

Urbanization is accelerating worldwide,especially in developing countries.Urbanization not only fragmented natural landscapes,but also posed a serious threat to biodiversity.The plant diversity investigation combined with the questionnaire were conducted along two 18km-width transects in east-west and north-south directions run across urban center of Shanghai to identify the spatial pattern of plant diversity along urban-rural gradient and to explore the mechanisms of how socioeconomic factors and green space management influence plant species diversity.My main findings are as following:(1)In five areas with different urbanization degree along urban-rural gradient,plant species richness of the total,exotic,woody,herbaceous,annual and perennial herbaceous species in urban area was significantly higher than those in rural area.The Simpson index and evenness index in urban area was lower than those in rural area.Shannon-Wiener index and native species richness had no significant difference between the areas.(2)Socioeconomic factors were the important drivers of plant species diversity in Shanghai.Both single factor analysis and Partial Least Squares Regression showed that there were correlations between socioeconomic factors and plant diversity.There were quadratic relationship between population density and Simpson index,Shannon-Wiener index and evenness index,respectively.Positive linear relationship existed between Simpson index,Shannon-Wiener index,evenness index and housing price and greening rate.Annual herbaceous species richness decreased with the increase of population density.With the rising of housing price,the species richness of the native,herbaceous and annual species increased first,and then decreased.In addition,woody species richness had a positive linear relationship with housing price.The species richness of the total,native,exotic,annual herb and perennial herb had a quadratic relationship with green coverage of the residential areas.(3)Green space management manners also affect plant species richness.Different weeding manners were found to have no significant effect on the species richness of the total,herbaceous and perennial herb.While the species richness of the native,exotic,woody and annual herb had significant difference with weeding methods.Manual combined with chemical weeding was a suitable manner which can not only remove weeds effectively,but also maintain plant diversity of the community.(4)Different weeding cycles had no significant effect on plant species richness.Meanwhile,the species richness of the total,native,herbaceous and perennial herb also had no significant difference with pruning cycle.Both exotic and woody plant richness decreased as the increasing of pruning cycle.The maximum species richness of annual herb was appeared in the no-pruning manner,and the minimum richness existed in the way of pruning cycle with 8-16 weeks.