| Biodiversity is the foundation of structural stability and function of urban ecosystem,and plays a key role in the improvement of urban ecological environment and the sustainable development of cities.Currently,urban biodiversity has become a hotspot in urban ecological research.With the acceleration of global urbanization,urban biodiversity faces many challenges.Urban biodiversity is influenced by natural environment,as well as human activities,which makes it much more complicated than that in natural conditions.The spatial distribution pattern and the underlying mechanisms of urban biodiversity are still unclear.Residential area is a place where human and environment interact frequently,so the plant diversity in its green space reflects the comprehensive consequences of society,economy and culture.In this study,residential area,one of the typical land use type in urban areas,was selected to explore the spatial pattern of urban plant diversity and the underlying mechanism of anthropogenic driving factors.These results can provide insights for management and conservation of plant diversity,as well as urban landscape planning and design in Shanghai.The specific questions were addressed 1)Whether there are differences among the plant diversity in residential green space on different build time? 2)Whether and how socioeconomic factors impact on plant diversity in residential green space? 3)Whether and how green space management and maintenance methods impact on plant diversity in residential areas? Total 121 residential areas were randomly selected by grid method within Shanghai outer ring road to examine the proposed questions.The following indexes were quantified: Firstly,αdiversity and β diversity were calculated based on field survey by further Modified-Whittaker plot.Besides,the indexes reflex socioeconomic level and green space management were analyzed based on the questionnaire survey,data collection and remote sensing image interpretation.Ultimately,the status quo of plant diversity in residential areas,and its anthropogenic driving forces were explored supported by the methods of variance analysis,univariate regression and partial least squares regression analysis.The main results are as follows:(1)Totally 466 vascular plant species,belonging to 116 families and 329 genera,were recorded in residential areas in Shanghai.Shannon-Wiener index and Pielou index of total species,native species and perennial herbaceous species showed an parabolic trend over time.For the beta diversity across residential areas of different ages,the rates of species accumulation ranged from 0.4 to 0.55.Compared with other groups,the residential areas built from 1980 to1994 and 2010 to 2015 had higher species accumulation rate.There was high similarity of species composition between the residential areas built from 2000 to 2004 and those from 2005 to 2009,but low similarity between the older ones(built up before 1994)and the newer ones(built up after 2010).We suggest that proper consideration should be given to the protection and improvement of the original plant resources in old residential areas in the urban renewal planning.(2)Socioeconomic factors do influence plant diversity in urban residential areas in Shanghai.However,The influences vary with plant taxa.Total species richness showed a binomial relationship with population density and greenspace coverage.Shannon-Wiener index and Pielou index both showed a binomial relationship with house age.Annual herbaceous plant richness had a negative linear correlation with house price,property fee,floor-area ratio,respectively.On the contrary,woody plant species richness exhibited a positive linear correlation with these factors,respectively.Native species richness showed a binomial relationship with greenspace coverage.Exotic species richness had a positive linear correlation with population,but had an inverse correlation with greenspace coverage.Comprehensive multifactor regression analysis revealed that population density,floor-area ratio and house price were the major anthropogenic drivers on most plant taxa.Furthermore,the hypotheses of "luxury effect" could only hold for woody plant,and the hypotheses of "legacy effect" could hold for Shannon-Wiener index and Pielou index of total species in Shanghai.(3)The frequency and method of greenspace management could influence species diversity of different plant taxa in different ways.The richness of total species,exotic species and woody plant species reached a peak when pruning frequency exceed 3 times per year.Besides,the richness of annual herbaceous plants significantly decreased with the increase of weeding frequency.Fertilizing and irrigating had no significant effect on plant species richness.We suggested that the intensity and method of greenspace management should be adjusted so as to achieve the purpose of maintaining and protecting urban biodiversity under moderate anthropogenic disturbance. |
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