Research On The Dominant Species And Habitat Characteristics Of The Hilly Zonal Plant Community Around Shanghai

The urban ecological environment is a hot issue that the government and residents are concerned about.The rational planning,scientific management and sustainable development of urban green space play an active role in promoting the construction of ecological cities.Natural-based Solution gradually advocated and implemented in urban green space construction shows that restoring and rebuilding urban vegetations with natural characteristics is inseparable from the understanding of natural characteristics and laws.And this indicates that the research and application of regional zonal vegetation is the basis of urban biodiversity protection and the construction of urban regional characteristic plant landscapes,and it is also an important way to improve the structure and function of urban ecosystems.In this paper,through the investigation of zonal plant communities with 29 samples occupying 400 m2 each in the suburban hills of Shanghai,Suzhou,Hangzhou and other places,using technical methods such as plant community science and quantitative ecology,the aspects of zonal plant community species composition,community structure,dominant population structure dynamics and distribution pattern,interspecific niche and habitat factor correlation,etc were studied.In terms of plant diversity in zonal plant communities:(1)244 species of vascular plants were found in 89 families,198 genera and 221 species of angiosperms in 77 families,180 genera,accounting for 90.57%of the total species;(2)Herbaceous plants and arbors in the survey area are the most,with 84 species and 79 species,respectively.Among them,perennial herbs are ranked first,with 59 species in 27 families and 51 genera,34 species of evergreen trees,and 45 species of deciduous trees.The statistics shows that there are more species of deciduous trees than evergreen trees but a greater number of evergreen trees than deciduous trees.(3)155 species of native species were investigated,accounting for 63.52%of the total species,and the species has a significant zonal advantage.The proportion of naturalized species and invasive alien species is relatively small,18 and 9 species respectively,and the interspecific competition between them is weak and they occupy less space.(4)The flora of the genera of seed plants is mainly distributed in the Pantropic and the North Temperate.Except for Temperate Asia,the rest of the flora are distributed.The flora composition is slightly inclined to the temperate zone,which is in line with location features of the geography of Shanghai and its surrounding areas.In terms of zonal plant community structure:(1)The zonal vegetation types in the suburban hills of Shanghai are mainly evergreen broad-leaved forest and evergreen deciduous broad-leaved forest.(2)The arbor layer of the community is mainly composed of evergreen trees such as Schima superba,Machilus thunbergii and Cyclobalanopsis glauca,and deciduous trees such as Celtis sinensis,Pinus massoniana and Quercus fabri;the shrub layer of the community is mainly composed of regenerated seedlings in arbor layer;Herb layer are mainly consisit of herbaceous plants which are easy to grow in pieces such as Trachelospermum jasminoides,Lygodium japonicum and Oplismenus undulatifolius.(3)The herb layer has the most abundant species,with 199 species,accounting for 81.89%of the total,and the arbor layer has the least species,with 87 species.Simpson index and Shannon-Weiner index show that the community species diversity is shrub layer>herb layer>arbor layer,and Pielou index shows shrub layer>arbor layer>herb layer.Relatively speaking,the species diversity of shrub layer is higher.In terms of the structural dynamics and ecological niche of the zonal dominant populations,five zonal dominant populations were selected for analysis:Schima superba,Machilus thunbergii,Cyclobalanopsis glauca,Castanopsis sclerophylla and Phoebe chekiangensis.The results are as follows:(1)The DBH class structure distribution of the dominant populations showed different degrees of progress,and the population structure was stable;the dynamic index of individual number change between adjacent DBH classes showed that each community belonged to a stable growth population.(2)Except for Phoebe chekiangensis population,the survival curves of the other populations are between Deevey-Ⅰ and Deevey-Ⅲ,and the survival curves all show vigorous growth in the early stage,obvious changes in the middle stage,and gradual stability in the later stage;according to the prediction on time series,the number of seedings of each dominant population is abundant,and the large-DBH-class individuals are increasing.In the short term in the future,each dominant population can still maintain its dominant position in the community.(3)The distribution pattern of dominant populations in most samples is cluster distribution,and only 4 samples are discretely distributed.(4)Plants with a higher niche in the dominant species communities are basically zonal plants.The dominant tree species and other major tree species have high similarity in resource utilization and strong inter-species correlation.In addition,there are also high interspecific associations between the zonal associated species in the communities.The habitat characteristics of the zonal plant biotopes in the suburbs of Shanghai:(1)The slope factor and aspect factor in the terrain factor have a high explanatory amount,and have a significant correlation with the CCA ranking axis.Species distribution is more inclined towards gentle sunny slopes.(2)Among the climatic factors,the factor of light intensity has the highest interpretation amount.Atmospheric moisture and photosynthetically active radiation are the main factors affecting the distribution of zonal species.(3)There is little difference in the values of soil factors in each community.Generally speaking,soil factors have little effect on the distribution of zonal plant communities and species,and they can all be adapted to the soil conditions of the survey plots.Relatively speaking,the total nitrogen content can explain more high.Therefore,in the process of ecological restoration of urban vegetation in Shanghai,it is necessary to consider:(1)Recommendations for zonal species selection and community structure such as increasing the type selection and frequency of dominant species,and finding the ornamental characteristics of zonal plant communities,and optimizing the spatial structure of zonal species by increasing the utilization rate of environmental resources.(2)Following the growth laws of zonal plant communities,protecting and renewing vegetation,improving forest density,adopting natural planting methods and other management and protection measures,and creating a suitable habitat for the growth and development of zonal tree species(Habitat creation)to optimize Shanghai’s urban green space system.