Study On The Relationship Between Plant Species Diversity And Landscape Pattern Change In Chongming Island From 2009 To 2018

The change of landscape pattern causes the change of biodiversity,and the change of landscape fragmentation degree has an impact on plant species diversity.In order to study the relationship between plant species diversity and landscape pattern change under human disturbance in Chongming Island of Shanghai,this study focused on the Chongming Island of Shanghai,selected the field survey data in 2009 and 2018,and analyzed the plant composition,structure and species diversity of sample sites in 2009 and 2018;At the same time,seven landscape indices,which reflect the fragmentation,diversity,regularity and convergence-divergence of the landscape,are selected to analyze the dynamic and spatial variation characteristics of landscape elements and landscape patterns in Chongming Island;Finally,correlation analysis and redundancy analysis(RDA)are used to explore the relationship between landscape pattern change and plant community species diversity.The main conclusions are as follows:(1)From 2009 to 2018,the diversity of different land use types is different.In2009,the most abundant land use type of species was cultivated land,followed by woodland and construction land.In 2018,the species of woodland were the most abundant,followed by construction land and cultivated land.From 2009 to 2018,with the construction of ecological island in Chongming Island,the species diversity of cultivated land,woodland and construction land increased,and the growth rate of species diversity of woodland reached 70.64%.(2)From 2009 to 2018,the main land use types of Chongming Island have changed in varying degrees,and the spatial differences of land use types in the east,west and central parts of Chongming Island are very large.On the whole,the area of construction land increased by 21.22%,which was the largest in Chongming Island;The area of unused land reduced by 16.46%;The second land use type is woodland,and the second land use type is farmland;Generally speaking,the area of construction land and forest land increased,and the area of unused land and cultivated land decreased most obviously.From the small scale of local area,the change of western region is the biggest,the construction land into cultivated land is the most obvious in the western region,and the area of unused land is decreasing;The increase of water area is most obvious in the central region.(3)From 2009 to 2018,the landscape pattern has changed in different degrees at different scales.At the scale of Chongming Island,the patch density(PD)of water area,forest land and unused land all decreased from 2009 to 2018;The connectivity(CONNECT)also decreased,indicating that the degree of fragmentation of water,forest and unused land decreased,on the contrary,the fragmentation of arable land and construction land increased.From 2009 to 2018,generally speaking,Chongming East Beach and West Beach were obviously disturbed by human activities,and the degree of landscape fragmentation increased significantly,but the change range of East Beach was smaller than that of West Beach;The change of landscape fragmentation in the central region was not significant;Construction land became the dominant patch type in the three land use types.(4)The impact of landscape fragmentation on plant species diversity in Chongming Island is increasing from 2009 to 2018.On the whole,the landscape index had an impact on plant species diversity of 28.8% in 2009 and 35.6% in 2018.The biggest change from 2009 to 2018 is that maximum patch index(LPI),which reflects the direction and strength of human activities,has the greatest impact on species diversity index,and landscape shape index(LSI)has changed from positive correlation to negative correlation.In 2009,the number of patches(NP)had the greatest impact on the species diversity index(H);In 2009,the landscape division index(DIVISION)had the greatest impact on the species evenness index(E);2018 average area(AREA-MN)has the greatest impact on species diversity index(H),and these three landscape pattern indices represent the degree of landscape fragmentation.At the local sub-scale,the impact of landscape index on species diversity in Chongming Xitan area changed from 61.6% in 2009 to 85.1% in 2018,which became the fastest changing area in the past ten years;From the perspective of time,the landscape index of the central region had the greatest impact on plant species diversity,reaching 80.8% in 2009 and 85.1% in 2018,The species diversity in the central region was more affected by the intensity and direction of human disturbance and landscape fragmentation index.(5)From 2009 to 2018,the correlation coefficient between the change ofShannon-Wiener index(H)and the change of landscape shape index was 0.328.The correlation coefficients of Simpson index(D)and species evenness(E)with patch number were 0.364 and 0.341,respectively.Negative correlation bet ween the three indices and COHESION was-0.377,-0.35 and-0.323,all of th em passed the significant positive correlation test at 0.01 level.