Plant And Bird Diversities In The Lakeside Of Dianchi Lake Under Diferent Land Management Intensity Levels

Wetland is one of the most diverse and dynamic ecosystems in the transition zone between terrestrial and aquatic ecosystems.In China,the wetland ecosystem is rapidly changing due to human activities,especially urbanization.The changes in land management are the key drivers of biodiversity change.Analysis and understanding of the relationship between them is the basis for rational natural resource management in the current urbanized environment.Most studies showed that the wetland area is an important variable to explain the diversity and abundance of plant and bird.Some studies have regarded wetlands as homogeneous objects,but there are often different types in an urban wetland environment,for example,the proportion of artificial vegetation,the intensity of human management and so on.The difference in the ecological process caused by them has an important impact on the wetland park which focused on maintaining biodiversity in the urban environment.In this study,we chose the Dianchi Lake to represent urban wetland.According to the management intensity levels,I classified the 31 sample sites into 4 types(high management intensity wetland(UP),medium-high management intensity level wetland(HM),medium management intensity level wetland(LM),low management intensity level wetland(RP)).I studied the effect of different land management intensity levels on plant diversity,community structure,and bird diversity.I selected 31 100 hm2 sample sites in the lakeside of Dianchi Lake,Kunming,Yunnan province,China.I studied the relationship between land management intensity levels,vegetation diversity,and bird diversity by using the RS and GIS technology,the dissimilarity index,NMDS analysis,one-way ANOVA analysis,and averaging the linear regression model based on Information-Theoretic approach.I got the following results.(1)In the past 35 years(from the 1980 s to 2015),the area of the built land and the forest land in the drainage basin of Dianchi Lake showed an upward trend,while the area of the grassland and the cultivated land showed a downward trend.In the past five years(2013-2018),in the 31 sample sites of the lakeside area of Dianchi Lake,the area of built land increased most dramatically,and forest land is the second most fast-growing land-use type.Among the four types of wetlands,the area of forest land,built land,cultivated land and river/pond was significantly different.At the same time,the submerged plant area,floating plant area,cultivated land area and the bare land area of LM and RP are higher.The area of pond/river,and grassland is higher in HM,and the built area and road area of UP are higher.(2)I record 410 vegetation species that belonged to 111 families and 293 genera in the 31 sample sites.In general,the proportion of exotic species in HM is the highest,followed by UP,RP,and LM.The distribution gradient of NMDS analysis showed that species in UP and HM are highly similar,and the characteristic vegetation species of Dianchi Lake are mostly distributed in RP and LM.There were 11 aquatic plant associations and 4 woody plant associations.The Trapa natans-Myriophyllum spicatum-Potamogeton lucens association mainly distributed in LM and RP.I analyzed the proportion of exotic species in 5 major aquatic plant associations and 4 woody plant associations.The result showed that the proportions of exotic species in LM and RP were mostly lower than HM.(3)The alpha diversity(species richness)and beta diversity of all birds and water birds were significantly different between different land management intensity levels.I used linear regression to analyze the relationship between the richness of the bird species and the land use/cover factor.According to my research,the land cover patterns that influenced bird species richness were the area of built land,submerged plant,pond,and the edge density of the emergent plant.The distribution gradient in NMDS of all birds and water birds indicates that the species in RP are quite different from the other three types,and LM is similar to RP type,while,birds of UP and HM type are very similar.The results showed that RP can maintain a higher beta diversity than LM,HM,and UP.This study showed that in urban wetlands represented by Dnchi Lake,different management intensity levels affect plant diversity,community structure,and bird diversity.The proportion of exotic plant species in UP and HM is higher than that in LM and RP.The local characteristic species are mostly distributed in the latter two types.Birds in LM and RP both showed higher alpha and beta diversity.Plant diversity is complex in an urban environment,and bird diversity is a better index to evaluate the impact of urbanization on the ecosystem.