Ecological Restoration Potential Of Mangroves In Guangdong Province Under Different Land-use Scenarios

Mangrove ecosystem is an important coastal wetland ecosystem with high ecological and economic value.Because mangrove forests are mainly distributed in the coastal intertidal zone,land use changes caused by anthropogenic activities such as aquaculture and urban expansion are constantly threatening the survival of mangroves.Ecological protection and restoration of mangroves is the current hot direction of ecological system protection and restoration in China.Selecting suitable areas for restoration is the key to improving the efficiency of mangrove restoration.Therefore,identifying the spatial distribution of potential mangrove restoration areas under different land use scenarios and exploring the impact of land use changes on mangrove restoration potential will provide important scientific basis for mangrove protection and restoration.In this study,the Max Ent model and the Dyna-CLUE model were coupled to establish a quantitative estimation method for the ecological restoration potential of mangroves under different land use scenarios.Taking Guangdong Province as the study site,15 true mangrove plants in Guangdong Province were divided into 7 groups according to the cold-tolerance of different true mangrove plants.Each group was carried out separately to analyze the ecological restoration potential of mangroves.Max Ent model was used to simulate the theoretical suitable distribution areas of mangrove groups under natural conditions.Base on the dominant factors determined mangroves suitable distribution ranges distribution maps of different groups were draw.Secondly,the Dyna-CLUE model was used to predict 2030 Guangdong Province coastal area land use potential under the current trend scenario(CTS),sustainable development scenario(SDS)and ecological protection scenario(EPS).The simulated land use patterns were used as constrains to estimate the actual space available for restoration of 7 groups of mangrove in the future,in order to analyze the scale and distribution of potential mangrove restoration areas in Guangdong Province.The main findings were as follows:(1)The main environmental factors affecting the distribution of mangroves in Guangdong Province were air temperature,sea surface temperature,precipitation and salinity.The G1(Kandelia obovata,Aegiceras corniculatum,Avicennia marina,Acanthus ilicifolius,Bruguiera gymnorhiza,Excoecaria agallocha)and G4(Acrostichum aureum)had the widest niche distribution range and the strongest adaptability to the environment;the G6(Acrostichum speciosum,Acanthus ebracteatus,Bruguiera sexangular,Bruguiera sexangula var.rhynchopetala)and G7(Sonneratia caseolaris)had the narrowest niche distribution range with the worst environmental adaptability,and they were more sensitive to precipitation and salinity.The prediction results about distribution of mangrove in Guangdong Province showed that theoretically suitable area of G1 was the most widely distributed between Zhanjiang City and Chaozhou City.However,the potential suitable area of G6 was the narrowest and located in South of Zhanjiang City.The area of potential mangrove habitats in the prefecture-level cities in Guangdong Province generally showed a gradual decrease from southwest to northeast.Among them,Zhanjiang City had the largest mangrove distribution,followed by Yangjiang City and Jiangmen City.(2)The prediction results of land use scenarios in Guangdong Province in 2030 showed that land use policies would have a strong impact on land use patterns.Under the CTS scenario,cultivated land and natural land were converted to construction land and aquaculture,and the area of wetland would be reduced.Under the SDS scenario,artificial land was mainly converted to forest land and construction land,and part of aquaculture was restored to wetland.Under the EPS scenario,cultivated land and aquaculture were restored to natural land,and the area of wetland would be increased significantly.(3)The results of the mangrove potential restoration area in Guangdong Province showed that G1 had the largest potential restoration area and G6 had the smallest potential restoration area under all scenarios.Under the CTS scenario,the area of the potential restoration area of mangroves would be reduced by 30%,the growth potential of it under the SDS scenario was between 3～16%,and 3%～49% under the EPS scenario.In all scenarios,the area of true mangrove species between 6-11 had the largest distribution in Guangdong Province.Under CTS scenario,the area with the distribution of species between 6 and 11 had a faster reduction rate.Under SDS and EPS scenarios,the area with the distribution between 8 and 11 species had a higher growth potential.The area of mangrove potential restoration and species diversity in Guangdong Province generally showed a gradual decrease from southwest to northeast.Among them,Zhanjiang City had the largest potential restoration area with the highest species diversity.In summary,this study assessed the ecological restoration potential of mangroves under the influence of land use by using the models coupled method.This method can effectively predict the spatial changes of mangrove potential habitats driven by coastal land use.The conclusion could provide scientific support for the spatial planning and policy formulation of regional mangrove protection and restoration.