Study On The Impact Of River And Lake Connectivity Projects On Waterbird Diversity And Their Habitat Stability

Jilin Xianghai National Nature Reserve is located in the Songnen Plain and is an important transit point on the East Asia-Australia migratory bird migration route.In recent years,a series of ecological engineering constructions have been carried out in the reserve,and changes in land use types,hydrological patterns and vegetation conditions have occurred.This study hypothesized that the ecological engineering construction in the region has brought about an impact on waterbird habitat stability,and waterbird diversity has responded to the habitat instability.In order to reveal the mechanism of ecological engineering construction on waterbird diversity and habitat stability,this project takes ecological engineering construction as the background,takes waterbird population diversity and distribution pattern as the object,and focuses on two wetland types,lakes and marshes,to carry out research on the impact of river-lake connectivity project on waterbirds in western Jilin,in order to measure the impact of ecological engineering construction on the stability of wetland habitat function,for the construction of Songnenhexiang National Park.The study will provide scientific guidance and basis for the planning of national wetland conservation and the construction of major wetland conservation projects.The main results are as follows.(1)During the period from 2010 to 2012 before the project,the diversity index of waterbird populations in the sanctuary showed a decreasing trend year by year,and waterbird populations were seriously degraded.After the construction of the ecological project in 2012,the biodiversity of waterbird populations recovered,but the number of waterbird species increased from 2010 to 2020,and the number of waterbird reached about seven times of the number before the project,among which the number of rare birds on the national key protection list increased significantly;the spatial distribution pattern of waterbird populations in the reserve changed.The spatial distribution pattern of waterbird populations in the reserve has changed,and the habitat type selection has changed from mainly lake and reservoir wetlands to mainly marsh wetlands.(2)The construction of ecological projects led to significant changes in land use types in the Xianghai Nature Reserve between 2010 and 2020.The area of arable land,forest land and settlements showed a decreasing trend;the land area of marshland,water bodies,grassland and saline land all expanded.The area of water bodies in the reserve showed an overall increasing trend,and water bodies were distributed in the central and southeastern part of the study area and in the section of the Huolin River,and the water bodies spread from the central lake reservoir to the southeastern and southwestern parts of the reserve.There are differences in the trend of NDVI index between different months.From the spatial distribution of vegetation,the vegetation cover in most areas showed an increasing trend from 2010 to 2020.The vegetation degradation in the study area was found to be mainly concentrated in the upper reaches of the Huolin River through the significance test.(3)Interannual variation in regional water diversions influenced water levels and waterbird populations in the reserve.The interannual water diversion threshold for maintaining waterbird habitat stability was 5.00×10~7 m~3,and waterbird populations were at a stable level when interannual water diversions were maintained at this level.The response trends of waterbird groups with different habitat preferences to water level differed,but the overall water level threshold for maintaining habitat stability of waterbirds in the region was about 1.5-2.0 m,when the water level depth is favorable for waterbird conservation in the region.The increase in the area of wetland water bodies and marsh habitats would increase the number and diversity of waterbirds;the increase in the area of cultivated land,woodland,grassland and saline land would produce stress on rare waterbirds.Two latent variables,habitat availability and heterogeneity,were found to have direct positive effects on waterbird diversity through structural equation modeling,with habitat availability having a more significant effect.The ecological projects implemented in the Xianghai Reserve provided a positive effect on waterbird population conservation in the early stages of construction,meeting their needs for habitat availability and heterogeneity.The appropriate amount of engineering diversions created heterogeneous water levels,created a variety of microhabitats,and met the habitat needs of different waterbird groups;in the later stages of construction,the increase in engineering diversions created stress on the waterbird populations in the reserve.Therefore,in the ecological engineering construction,water diversions should reasonably regulate wetland replenishment,optimize wetland hydrological patterns,and strengthen wetland water level regulation to maintain good habitat quality conditions for waterbirds.