Research On The Carbon Footprint Of Coastal Wetlands Under The Interference Of Human Activities

As an important ecosystem in coastal areas,coastal wetland is not only affected by the interaction between land and ocean,but also by human activities.Special vegetation,animal,hydrological and soil conditions make coastal wetland having higher natural productivity and succession rate,which makes it an important carbon source and sink area.Under the influence of human activities such as reclamation and urban traffic construction,the land-use pattern of coastal wetland has gradually changed from natural to artificial,and the rate of change is increasing,nevertheless,the landscape transformation of coastal wetlands plays an important role in the increase and decrease of carbon emissions and carbon absorption,and the change of carbon will have corresponding reaction to human activities and ecological environment.The study and assessment of the evolution and carbon footprint of coastal wetlands under different human interference intensities is conducive to the promotion of in-depth research on the development and protection of coastal wetlands,and the assessment of the impact of the development and protection of coastal wetlands,which is of great significance to the carbon emission reduction,carbon trading and carbon compensation of coastal wetlands and even the whole region.Therefore,Based on the landscape data of 8 periods in 1987,1991,1996,2000,2004,2008,2013 and 2017,using landscape pattern index,spatial analysis and other methods,this study analyzes the spatial-temporal evolution characteristics of Yancheng National Nature Reserve in 30 years.On the basis of landscape change,combined with carbon emission coefficient,this paper analyzes the temporal and spatial evolution characteristics of carbon emission and carbon footprint in Yancheng National Nature Reserve,and then discusses the correlation between landscape change and carbon footprint.At the same time,IDRISI software is used to simulate and predict the results of landscape and carbon footprint of Yancheng National Nature Reserve under the interference of different human activities in 2026,and the Protection Countermeasures of Yancheng National Nature Reserve are put forward from the perspective of carbon compensation,providing theoretical reference for the subsequent development and protection of Yancheng National Nature Reserve.The main conclusions are as follows:(1)In terms of the landscape evolution of Yancheng National Nature Reserve,large changes occurred between various landscape types under the interference of human activities from 1987 to 2017.Natural wetlands gradually transformed into artificial wetlands and nonwetland types.The degree of artificial and fragmentation had gradually increased.From the perspective of dynamic degree,the overall trend was decreasing,which indicated that the change rate was slowing down.Among them,the dynamic degree of fish pool,dry pool,building and Cordgrass land changes greatly,and the dynamic degree of seawater and tidal flat was the smallest.From the perspective of landscape type transformation,The seawater and tidal flat,aquafarm and dry pool had obvious mutual transformation,Three types of vegetation landscape mainly focused on internal transformation;Farmland,aquafarm and dry pool mainly occurred in Dafeng District and Dongtai City,the conversion of saltwork was concentrated in Xiangshui County,and the conversion of cordgrass was concentrated in Dafeng District and Dongtai coastal area,with less conversion of building spatial location,but its distribution area was gradually expanding.From the perspective of landscape index changes,the number and density of patches,diversity index and evenness index were all increased,the natural wetland landscape presented a centralization,while the constructed wetland landscape and non-wetland landscape showed a trend of fragmentation.(2)In terms of change of carbon footprint in Yancheng National Nature Reserve,the carbon absorption was always higher than the carbon emission,but the carbon absorption surplus decreased rapidly.From the perspective of dynamic degree of carbon emission,the dynamic degree of carbon emission of Seawater,tidal flat,reedbed and Seepweed saltwork and farmland had little changed and kept relatively stable,while other landscape types were large.From the perspective of carbon emission change characteristics,from 1987 to 2013,the distribution area of-999.99—-500 t and-499.99—0 t carbon emissions were dominant,while the area of net carbon emissions below-1000 t was gradually reduced,and the area of over 500 t was gradually increased.In 2017,because of the decrease of building and the expansion of cordgrass land,there were different changes.From the perspective of the change characteristics of carbon footprint,in addition to the slight decline in 2013—2017,the carbon footprint kept the overall increase trend,and its spatial distribution was very consistent with the spatial distribution of carbon emissions.From the perspective of correlation analysis,it can be found that NPP was significantly related to edge density(ED),shape index(LSI),diversity index(SHDI),evenness index(SHEI)and carbon footprint.Carbon footprint was significantly related to diversity index(SHDI),evenness index(SHEI)and NPP.(3)In terms of carbon footprint simulation and prediction of Yancheng National Nature Reserve,there were obvious differences in landscape,carbon emissions and carbon footprint changes under four different scenarios,especially under two scenarios of policy planning and ecological protection.From the perspective of landscape simulation,the trend of change of four different scenarios was the decrease of seawater,tidal flat and saltwork,While the area of other landscape types increased,but the changing area had its own characteristics.From the perspective of carbon emission simulation,carbon absorption was greater than carbon emission under the ecological protection scenario,current utilization scenario and natural development scenario,and the reserve still played a role of carbon pool,while carbon emission was greater than carbon absorption under the policy planning scenario.In terms of carbon footprints,the carbon footprints under the three scenarios of current utilization,natural development and ecological protection were all negative.Compared with 2017,in 2026,the areas with positive carbon footprints increased significantly,while the areas with carbon footprints of below-500 hm2 decreased,but the change of carbon footprints in the core area was very small.(4)In terms of carbon compensation,it involved many elements such as the object,standard,method and amount of carbon compensation.Therefore,this study discussed the basic framework,subject and object,principle,standard and method of carbon compensation from the theoretical level.Under the two compensation methods of government and market,the compensation model was used to calculate the carbon compensation obtained by Yancheng National Nature Reserve in 2017.The compensation amount was 12.71 million yuan.In view of some problems faced by carbon compensation and nature reserves,this paper put forward six countermeasures and suggestions:improving the laws and regulations of carbon compensation,establishing carbon compensation calculation standards and systems,giving full play to the dominant position of government carbon compensation,improving carbon trading market,implementing carbon compensation zoning and limiting the development and utilization of wetlands.The above carbon compensation framework could also be applied to other nature reserve areas.