Study On Waterbird Ecological Corridor Identification And Ecological Corridor Coastal Area Construction Model In Guangdong-hong Kong-macao Greater Bay Area

The trend of global biodiversity decline has not been curtailed effectively,and the sustainable development of biodiversity has become a shared objective of the world.Ecological corridor construction is a key measure for biodiversity conservation.The Guangdong–Hong Kong–Macao Greater Bay Area(GBA)is the wintering site and transit station of the “East Asia–Australia” migration route of global migratory birds,which plays an exceptional role in the protection of global waterbird diversity.Nevertheless,rapid urbanization has intensified habitat fragmentation and shrinkage of waterbirds,threatening the sustainable development of waterbird diversity.However,the application of ecological corridors to the improvement of urban biodiversity is faced with great difficulties,which are mainly reflected in the following aspects: first,how to identify the conservation network of waterbird ecological corridors in small spatial scale mega-cities;Second,how to build an ecological corridor in a megacity with highly homogenous habitats?Therefore,this study takes the identification of waterbird ecological corridors and the construction model of ecological corridors in the Coastal area of the Guangdong-Hong KongMacao Greater Bay Area as an example to explore the identification and construction methods of ecological corridors under the condition of small spatial scale and highly homogenous habitat of mega-cities,so as to provide reference for the improvement of urban biodiversity.Thus,based on the long-term survey and monitoring distribution data of waterbirds in the GBA,this study first constructs the waterbird ecological corridor conservation network in the GBA by combining the habitat suitability evaluation model,minimum resistance model,kernel density analysis,and priority principle.Finally,we determine the factors driving waterbird diversity using redundancy analysis.Accordingly,this study also discusses the effect of the ratio of beach area to mangrove area on waterbird diversity.The findings of this study will contribute to the design of waterbird ecological corridors in the GBA and the construction of coastal corridors.The main research results are as follows:1.Design of waterbird ecological corridor in the GBA(1)The GBA is a crucial habitat for waterbirdsThere are 127 species of waterbirds in 18 families and 7 orders,among which 11 species are listed in China’s National Key Protected Species List.Different types of various grades of water birds habitat area is small,the space distribution there are remarkable space differences,but overall,good(suitable,more suitable)distributed in wetland habitat suitability of rich resources and good cover small area,human interference,and not strong suitability area are mainly distributed in human activities,such as forest area in the city proper.(2)Screening of focus species of waterbird ecological corridor in the GBAThe focus species primarily included: shorebirds,wading birds,open water waterbirds,and waterfowl,accounting for 44.09 % of the total number of waterbirds(127 species).(3)Selection of waterbird ecological corridor nodes in the GBAWaterbird ecological corridors had 113 corridor nodes,which were primarily important habitat sites of waterbirds;22 of these corridor nodes were located in adaptive habitats(19.47%),36 in more suitable habitats(31.86%),and 55 in generally suitable habitats(48.67%).Among the 113 corridor nodes,14 were source nodes,accounting for 12.39% of the total,47 were stepping stones,accounting for 41.59%,and 52 were sinks,accounting for 46.2%.(4)Determination of a hierarchical conservation network for waterbird ecological corridors in the GBAThe hierarchical conservation spatial network of waterbird ecological corridors(main corridor,secondary corridor,and sub-corridor)connects coastal beaches,estuaries,lakes,rivers,reservoirs,ponds,and other habitats to fulfill the needs of waterbird diffusion.There are 214 conservation networks,with a total of 4855.67 km,among which 47 are main corridors,with a total of 1153.31 km,which are primarily distributed in coastal tidal flats,Pearl River Estuary,Tong Lake,Baipanzhu Reservoir,Liuxi River,and other areas outside the built-up area.There are 103 secondary corridors(2389.65km),primarily distributed in the Dongjiang River,Xijiang River,and other rivers in the built area,as well as Liuxi River,Danshui River,and western coastal beach outside the built-up area.Furthermore,there are 65 branch corridors(with a total of 1406.23 km),mainly distributed in the Dongjiang River,Xijiang River,and Pearl River tributaries in the built area.2.Coastal area construction of the ecological corridor in the GBA(1)Important factors driving the diversity of coastal waterbirdsIn the coastal region,water area,mangrove area,tidal flat area,aquaculture area,road density,and construction land area were critical factors driving waterbird diversity.Two factors,mangrove area and tidal flat area,were the main driving factors of waterbird diversity,especially shorebirds,wading birds,and waterbirds living in open water,while road density and construction land were the negative driving factors of waterbird diversity.(2)The area ratio between beach and mangrove should be regulated scientifically in the construction of coastal waterbird ecological corridorIn the mangrove ecosystem,)the relationship between the ratios of tidal flats area to mangrove area [x] and shorebird richness [f(x)] and abundance [g(x)] satisfied the cubic function equation f(x)= 0.106x3-2.147x2 + 11.269x(0.0265≤x ≤ 13.8100)(R2 = 0.714,P =0.000),g(x)= 0.008x3-0.189x2 + 1.124x(0.0265≤ x ≤ 13.8100)(R2 = 0.713,P = 0.000).The optimal ratio of mudflat to mangrove area was 3.5662 or 3.9785,under which mangrove planting and management could improve the diversity of waterbirds.Hence,in the construction of the coastal corridor of the GBA,mangrove planting should be adopted,and the ratio of mudflat to mangrove area should be considered.