Dynamics Of Plant Community In 1hm~2 Plots Of Shanghai Bay Forest Park And Its Enlightenment

With the acceleration of global urbanization,urban vegetation is becoming more and more important.In order to study the dynamic changes of woody plants,we established a 1 hm2 permanent fixed dynamic monitoring plot in the Bay National Forest Park.We summarized and discussed The dynamic characteristics of the woody plant community in the dynamic monitoring plot of the Bay Forest Park from the aspects structure characteristics,the dynamic comparison of different communities and thedynamic characteristics of dominant populations.Based on the analysis of the community dynamics,some suggestions on the construction of urban greenland community structure were put forward.The results from this study not only provide the theory basis for construction and maintenance management of Shanghais urban forest,but also strengthen urban forest biodiversity monitoring network in Shanghai.Main conclusions are as follows:(1)Community species composition and important value dynamics:There were 72 species of vascular plants in the plot,which belonged to 31 families and 67 genera,and a total of 12 species of woody plants were recorded,belonging to 11 families and 12 genera in 2011.A total of 48 species of vascular plants were recorded in the plot in 2016,includ 20 species of woody plants,belonging to 15 families and 18 genera.The important values of Ligustrum lucidum,Toona sinensis,Melia azedarach,Bischofia polycarpa,Michelia chapensis and Photinia davidsoniae were reduced,and the reductions were 2.26,2.08,1.1,0.69,0.45 and 0.07.The important values of Sapium sebiferum,Cinnamomum camphora,Koelreuteria bipinnata,Swida wilsoniana and Camptotheca acuminata were increased,increased by 3.84、1.43、0.87、0.69 and 0.29 over the past five years.(2)Study on Community Structure Dynamics:The population structure and vertical structure of the plot community were single peak type in 2011.The vertical structure of the plot community was intermittently grown,and the population diameter structure showed a single peak growth in 2016.The distribution pattern of Koelreuteria bipinnata and Sapium sebiferum gradually showed a trend of random distribution in 5 years.The pattern of other population points is basically the same as that of 5 years ago.(3)Study on Density and Community Update of Different Communities:The density of Melia azedarach-Ligustrum lucidum community was the largest decreased in seven communities,and the number of plant deaths was the highest.Other followed by the Ligustrum lucidum community>Koelreuteria bipinnata-Toona sinensis-Cinnamomum camphora Community>Photinia davidsoniae-Camptotheca acuminata-Swida wilsoniana community>Photinia davidsoniae-Sapium sebiferum-Camptotheca acuminate community>Camptotheca acuminata-Ligustrum lucidum community>Swida wilsoniana-Camptotheca acuminata-Ligustrum lucidum community.The update of different community plants was as follows:Swida wilsoniana-Camptotheca acuminata-Ligustrum lucidum community>Camptotheca acuminata-Ligustrum lucidum community>Photinia davidsoniae-Sapium sebiferum-Camptotheca acuminata community>Photinia davidsoniae-Camptotheca acuminata-Swida wilsoniana community>Ligustrum lucidum community>Melia azedarach-Ligustrum lucidum community>Koelreuteria bipinnata-Toona sinensis-Cinnamomum camphora community.(4)The trend of species diversity index of different communities was significantly different,and the trend of index was basically the same.The results showed that the Photinia davidsoniae-Camptotheca acuminata-Swida wilsoniana community>Photinia davidsoniae-Sapium sebiferum-Camptotheca acuminata community>Swida wilsoniana-Camptotheca acuminata-Ligustrum lucidum community>Koelreuteria bipinnata-Toona sinensis-Cinnamomum camphora community>Melia azedarach-Ligustrum lucidum community>Camptotheca acuminata-Ligustrum lucidum community>Ligustrum lucidum community.(5)Effects of Soil Physical Properties on Vegetation Regeneration in Communities:In the soil layer 0-30cm,the soil capillary porosity was significantly correlated with the average number of seedlings per 100m2 in the P>0.01 level,while the total soil porosity and soil maximum water holding capacity with the average number of seedlings per 100m2 in P>0.01 Level,both showed negative correlation.In the soil layer 30-60cm,the correlation between the soil physical index and the average number of seedlings per 100m2 of the community didn’t reach the significant level(P>0.05).(6)Effects of Community Density and Soil Physical Properties on Community Species Diversity:The correlation between community density and community diversity index was not significant(P>0.05),but the trend was consistent.In the soil layer 30-60cm,the Simpson index was significantly correlated with soil capillary porosity at P>0.05 level,and the Shannon-Wiener index and Pielou evenness index were significantly correlated with soil total porosity at P>0.05 level.All indexs are negatively correlated.(7)The dynamics of woody plant regeneration:The evergreen shrubs Elaeagnus pungens,Pittosporum tobira occupy the advantage in the woody plant regeneration seedlings.A total of 1246 seedlings were recorded,and Swida wilsoniana,Photinia davidsorniae and Ligustrum lucidum total number of seedlings was 89.4%in the construction of species.Other species update ability is poor or no update,the proportion is below 10%.(8)Density and Crown dynamics of dominant populations:The density of dominant population showed that the density of other populations showed a decreasing trend,except for the Swida wilsoniana population.The density reduction of Ligustrum lucidum population was the largest,followed by the Koelreuteria bipinnata,Bischofia polycarpa,Camptotheca acuminata,Sapium sebiferum,Photinia davidsoniae and the Cinnamomum camphora population.The number of the plant,s crowns decreased more than that of increased in the dominant population.The Sapium sebiferum、Cinnamomum camphora and Ligustrum lucidum population was most obvious.The results about the correlation between the population dynamics and the population density showed that:The reduced number of the population crowns in dominant population was significantly correlated with population density reduction at the P>0.05 level,And the population crowns plants with the population density was significant correlation the P>0.01 level.(9)Construction of urban greenland plant community:Based on the dynamic study of plant community in 1hm2 plots of Bay National Forest Park,the following suggestions were put forward.First,a good site conditions are the basis of plant growth.Secondly,the plants selection and allocation should be reasonable.Finally,the staging strategy should be adopted in the process of community growth.