Study On Survival Natural Vegetation And Its Dynamics During The Past Ten Years In Sheshan Area,Shanghai

Survival natural vegetation is the natural legacy of a valuable asset in the urban backdrop of the rapid expansion of. As the Shanghai Sheshan one of the only two survival natural vegetation,its comprehensive and systematic analysis of research has important significance for the local zone aspects of vegetation,urban forest management and protection of urban landscaping provide a theoretical basis and practical advice.The thesis makes study of the vegetation in11hills of Sheshan area,Shanghai,in2012-2013.In order to find out the structure,species composition and distribution characteristic of the vegetable community,42tree communities’ cases have been investigated by identifying and measuring all trees in quadrants established in the forest,in which plot area is20m×20m. On this basis,analyzed by PC-ORD, combined with the plot of each species relative dominance clustering divided community types,and to calculate the various diversity index.By using"space replacing time"method,seven main tree species’population age structure was analyzed,in order to speculate the dynamic development of the local vegetation in Sheshan. Bray-Curtis cluster and CCA ordination analysis has been used to reflect the relationship betweenthe herb community and environment. And refer to the existing results,studied the sheshan area community dynamics characteristics in10years.Some mainly results are given as follows:(1)42plant communities have been investigated and compiled.There are162species,78genus and143family plants recorded in this area. Via PC-ORD software, tree communities were grouped into15types in the method of Cluster analysis,in which there were1evergreen broad-leaved forests(EBLF).Deciduous broad-leaved and mixed forests occupy obvious advantage in Sheshan area. Select the soil total nitrogen(TN),soil total phosphorus(TP),soil organic matter(OMC)and soil pH value(pH)four environmental factors,CCA ordination analysis has been used to reflect the relationship between the community and environment. The results show that the chosen four soil factors on the tree layer species composition and distribution have obvious effect.(2)Calculate the various diversity index of the tree layer and regeneration layer by PC-ORD. Using species richness(S),Simpson index(D),Shannon-Wiener index(H),evenness index(E)as an indicator to measure the diversity of the various places within the different layers. In the tree layer,species richness and evenness of the mixed forest are significantly higher than the single dominant species communities. The richness of regeneration layer species was significantly higher than the tree layer. The Simpson index and Shannon-Wiener index of the community types whose structure are more stable are higher. The diversity indexes of regeneration layer are higher than tree layer.(3)By using "space replacing time"method,seven main tree species’population age structure was analyzed,including Cinnamomum camphora,Celtis sinensis,Quercus aliena,Broussonetia papyrifera,Quercus fabri,Robinia pseudoacacia and Firmiana simplex,in order to speculate the dynamic development of the local vegetation in Sheshan..The7species have been divided into2types:Unimodal Quercus aliena and Firmiana simplex,Sporadic Broussonetia papyrifera,Quercus fabri,Robinia pseudoacacia,Cinnamomum camphor a and Celtis sinensis.(4)The comparation between tree layer and regeneration layer has been studied.The number of species in regeneration is larger than it in tree layer;deciduous trees accounted for the largest proportion in both the tree layer and regeneration layer; evergreen tree accounted for a smaller proportion in regeneration layer,the proportion of deciduous shrub an evergreen shrub in regeneration layer were significantly higher than the distribution of tree layer; overall,the deciduous trees in the community are clearly advantageous.Select the soil total nitrogen(TN),soil total phosphorus (TP),soil organic matter(OMC),soil pH value(pH),total BA value of the tree layer and the coverage of the tree layer6environmental factors,CCA ordination analysis has been used to reflect the relationship between the regeneration layer community and environment. The results show that the chosen six soil factors on the regeneration layer species composition and distribution have obvious effect,except the soil organic matter(OMC).(5)Refer to the existing results,the evergreen broad-leaved species increased in almost ten years,as same as the deciduous broad-leaved tree species;deciduous broad-leaved shrubs and lianas has little changed,the conifer species increased;the annual herbaceous species reduced as the perennial herbaceous species increased. Tree communities were grouped into15types in the method of Cluster analysis,in which there were only1evergreen broad-leaved forests(EBLF).Deciduous broad-leaved and mixed forests occupy obvious advantage in Sheshan area. Cinnamomum camphora changed from Inverse-J to Sporadic,Cltis sinensis changed from L to Sporadic. Broussonetia papyrifera,Quercus fabri,Robinia pseudoacacia little changed. Castanopsis sclerophylla is Sporadic in2004,it is not able to be the dominant specie in Sheshan now,because of the discontinuous and fluctuated upgrade.