Ecological Security Assessment Of Coastal Wetland Ecosystems In Fangchenggang, Guangxi Under Climate Change

The Sixth Assessment Report of the Intergovernmental Panel on Climate Change(IPCC)pointed out that under the background of anthropogenic climate change,the global climate will continue to warm,the sea level will rise to an unprecedented height,and have a significant impact on the structure and function of the global coastal ecosystems.China is a large maritime country with a long coastline.Coastal wetland is a special ecosystem located at the junction of land and sea.It is extremely sensitive to the sea level rise caused by global warming and is a typical ecologically fragile area.Therefore,the impact of sea level rise on coastal wetlands under climate change is studied,the vulnerability index system of coastal wetlands under sea level rise is constructed,and the ecological security of coastal wetlands is evaluated in space to provide an important basis for ensuring the security of coastal ecosystem.This study took the coastal wetland of Fangchenggang City,Guangxi as the research object,using field visits combined with qualitative and quantitative research methods,and based on the IPCC vulnerability definition and the theoretical basis of the "source-pathway-receptor-consequence"(SPRC)conceptual model,By analyzing how the sea-level rise caused by climate change acts on the coastal wetland ecosystem and causes sensitive results,a process-based vulnerability assessment index system of coastal wetland is constructed,which provides a method for reference for quantitative assessment of coastal wetland ecological security.According to the predicted results,the spatial and temporal distribution of vulnerability of coastal wetlands in Fangchenggang City is as follows:(1)In the short term,under the SSP5-8.5 scenario,sea level rise has a great impact on the plain and mangrove habitats,and the vulnerability levels are Ⅲ and Ⅳ,mainly concentrated in the Qisha Peninsula.(2)In the medium term,under the scenarios of SSP1-2.6 and SSP2-4.5,part of the plain habitat was Ⅳ,and the affected areas spread to the East Bay of Fangchenggang,Beilun estuary and the lower part of Zhuzhu Bay,while under the scenarios of SSP5-8.5,some mangrove habitat vulnerability levels were Ⅲ and Ⅳ,and the affected areas were concentrated in Qisha Peninsula,East Bay of Fangchenggang and Zhuzhu Bay.(3)In the long term,the highly vulnerable coastal wetland area is located in Qisha Peninsula and East Bay of Fangchenggang,while the moderately vulnerable coastal wetland area is mainly located in Pearl Bay and Beilun estuary.4)To sum up,the spatial distribution of vulnerability levels of coastal wetlands in Fangchenggang of Guangxi is as follows from high to low: Qisha Peninsula >Fangcheng East Bay > Zhuzhu Bay > Fangcheng West Bay > Beilun Estuary.Therefore,the spatial and temporal distribution of coastal wetland ecological security from high to low in Fangchenggang City is as follows: Beilun Estuary,Fangcheng West Bay,Pearl Bay,Fangcheng East Bay,Qisha Peninsula.According to the prediction results of different sea level rise scenarios(SSP1-2.6,SSP2-4.5 and SSP5-8.5 scenarios)and different periods,strategies and mitigation measures for coping with sea level rise of Fangchenggang coastal wetland were proposed,and suggestions were put forward for Fangchenggang coastal wetland:(1)For mangrove wetlands: Firstly,mangrove wetlands should be restored through seedling cultivation and afforestation to expand the area of mangrove forests;Secondly,in order to better protect and utilize mangrove wetlands,we should combine fishery and aquaculture,ecotourism and biodiversity restoration.Thirdly,in view of the severely degraded wetlands,wetland ecosystem functions should be strengthened by planting plant communities in the buffer zone,restoring and regulating wetland hydrological conditions,controlling the invasion of alien species,and creating suitable habitat for wild birds.Finally,the non-Yilin shoal is effectively used to transform the bare shoal into mangrove wetland.(2)For the Guangtan wetland that has sunk into the sea: Firstly,through scientific sediment management,such as engineering measures,planting green to promote sedimentation,to promote sediment deposition,to achieve the purpose of expanding the new wetland;Secondly,to prevent coastal erosion again,combined with ecological engineering to protect and restore it,to provide a new idea for the protection of waterfowl habitat.