| Coastal zone ecosystem is a typical ecological fragile zone,which is a multi-functional,multi-interface and multi-process ecosystem.The coastal zone ecosystem is rich primary productivity,but is disturbed from the ocean and land frequently and has poor stability.The coastal ecosystem is often affected by typhoons,storms,floods,droughts,pollution and other disasters.Theses disasters and the secondary disasters caused by them,and the interaction among them constitute a very complex disaster system.Ecosystem capacity of disaster bearing capacity and the ability to rebuild after the disaster can reflect the acceptable risk of ecosystem and the ecosystem health under the complex disaster system.Since twenty-first Century agenda for the United Nations Conference on environment and development in 1992 put forward that coastal states are committed to the comprehensive management and sustainable development of coastal and marine environment under the jurisdiction of its state,how to coordinate the relationship between regional comprehensive carrying capacity and sustainable development of economy and society,and to strengthen and implement the coastal zone integrated management and sustainable development strategy have been focused by the government and the society.The complexity and function of disaster system are discussed,ecosystem capacity of disaster bearing capacity and the ability to rebuild after the disaster are researched through the in-depth study on the continued evolution of coastal ecosystem under the complex disaster risk,which will explore the risk level and health status of coastal zone ecosystem and provide a scientific basis for the development of comprehensive management and disaster management in the coastal zone.In this paper,when Dongshan Island in Fujian province is selected as the research area,the three key periods(1994,2003 and 2011)of the human ecological process of Dongshan Island are taken as research time.Ecosystem capacity of disaster bearing capacity and ecosystem health of Dongshan Island are explored on the basis of the basic data,remote sensing images,social economic data and previous research results.Firstly,the landscape change in Dongshan Island from 1994 to 2011 is analyzed.The overall objective of the analysis is to characterize the temporal and spatial pattern of change and to explore its potential ecological impact.Secondly,using remote sensing images of Dongshan Island in 1994,2003 and 2011,the geographically weighted model is selected to analyze the dynamic changes and the driving factors of land use in Dongshan Island And thirdly,large patch index(LPI)and patch density(PD)have been chosen as landscape fragmentation index.26 buffer zones,each being 500m wide,are divided from the coast to inland.Meanwhile,we select four sample lines,which extend 200m,500m,1000m from coastline and across the center of the town.With GIS and FRAGSTATS,the landscape spatial patterns of each buffer zone and sample lines were analyzed.Fourthly,a comprehensive protection efficiency index(CPEI)has been proposed in conjunction with the development of a comprehensive assessment index system.Values of CPEI for 31 reaches are obtained by projection of a pursuit model.Based on normalized data from the evaluation index and CPEI,ANOVA analysis has been used to test the influence of various bays and forms of land use on coastal shelterbelts.Fifthly,ecological connectivity at regional scale is supported by remote sensing images of 1994,2003 and 2011 in Dongshan island,China.Using GIS,the method allows the elaboration of a diagnose of the connectivity of landscape ecosystems,on the basis of a previously defined set of ecological functional areas,and a computational cost-distance model which includes the barrier effect.Sixthly,the assessment of disaster ecological risk are investigated by means of selecting typhoon,rainstorm and gale as major disaster on the basis of assessing disaster risk probability and establishing ecological risk indices from disaster vulnerability,disaster bearing capacity and disaster restoring force.Spatial correlation analysis and statistical analysis methods are used to analyze ecological risk dynamics.Finally,from the perspective of the ecosystem service function of heavy rainfall regulation,the ecosystem of Dongshan Island is divided into the ecological service providing areas and service benefiting areas linked up by riversystem which is extracted by the hydrological analysis function of ArcGIS.And then the index system of the ecological service providing areas and service benefiting areas are selected and the weight of index are obtain by principal component analysis,and the health of the ecological service providing areas and service benefiting areas are evaluated.Primary results are as follows:(1)The results of landscape change revealed that areas of forest and construction land increased significantly from 1994 to 2011.From the transfer matrix of land use,forest,construction land,farmland and other land changed significantly,forest and construction land were moved into much more,and other land were moved out highly.From the analysis of the potential ecological impact of landscape changes,the farmland changed into construction and road,forest and grass changed into construction and road,forest and grass changed into farmland whose area percent are 4.3%,2.47%,1.99%were the main track to make negative ecological impact.Therefore,the rapid increase of artificial constant mainly caused the land hardened,vegetation coverage reduced,the ecological connectivity reduced,thus affecting the protection and the preservation of biodiversity and habitat.The rise of forest area made the improvement of the ecological environment quality,but the increase of fragmentation of forest,grass and water made ecological functions such as the biological protection,disaster prevention and mitigation decline.At the same time,increasing urbanization,the agglomeration of construction land made the negative impacts on ecological environment appear.(2)Using remote sensing images of Dongshan Island in 1994,2003 and 2011,the geographically weighted model was selected to analyze the dynamic changes and the driving factors of land use in Dongshan Island.The results showed that the original construction foundation and original forest had a great impact on the land use change,while natural factors and landscape factors had a little impact.Finally,the six factors of the construction foundation and forest categories were analyzed by geographically weighted regression,the spatial differences of the regression coefficient of the factors were expressed to reflect the impact of the factors on land use trajectory.And the low regression coefficient area of road distance factor had expanded in 2003 than in 1994,which indicated the expanded trend of artificial land,especially in coastal zone.The high regression coefficient area of forest distance factor had a significant expansion in 2003 than in 1994,which showed that the range of natural land was significantly extended along with the development of the ecological construction of Dongshan Island and people continued to develop the forest in the original non-forest or away from the original forest The low regression coefficient area of construction distance factor had spread in 2003 than in 1994,which indicated the artificial land was extended obviously and to peripheral area of original towns and the coastal area.Geographical weighted regression can reflect the spatial heterogeneity of different factors on the regression equation by means of adding the change parameters expressing spatial heterogeneity.Therefore,geographical weighted regression is suitable for the simulation of land use pattern,and it can be used to analyze the relationship between regional land use and its driving factors,and to express the influence of the driving force of land use change in different spatial positions.(3)The characteristic scale for analyzing landscape fragmentation of the study area was 1000m,based on the semi-variable function and the moving windowmethod.The degree of landscape fragmentation increased with time.The landscape fragmentation continued to decrease in coastal zone,the northwest and south zone with forest,while in the town and farmland area of the north and south of the study area,human disturbance was stronger and the fragmentation was increasing.The coastal zone of 500m and 1000m from coastline were disturbed strongly by human,and the fragmentation wastgrowing.The artificial disturbance,which tended to be scattered,created fluctuation significantly of fragmentation index curve with time.Urbanization,tourism and agriculture development should be the main driving factors of landscape fragmentation.Using Pearson correlation coefficient,we analyzed the correlation of landscape fragmentation and landscape other pattern,which were found to have strong correlation.They indicated chosen landscape fragmentation index can reflect the basic characteristics of landscape pattern change of the study area.(4)Coastal shelter forest in China is under threat of destruction and degradation because of the impact of human activities.Therefore,a comprehensive protection efficiency assessment of the coastal shelterbelt is a significant component of shelter-forest remediation planning and sustainable management.A comprehensive protection efficiency index(CPEI)has been proposed in conjunction with the development of a comprehensive assessment index system.This system,incorporating seven indices,was based on the structure of the shelter forest and principles of index selection.Values of CPEI for 31 reaches were obtained by projection of a pursuit model.Based on normalized data from the evaluation index and CPEI,ANOVA analysis has been used to test the influence of various bays and forms of land use on coastal shelterbelts.The results showed that the comprehensive situation of coastal shelter-forest in Dongshan island was in the"common" grade.CPEI had significant differences in different bay.Most of shelter-forest indexes had significant differences in different land use types.(5)The main disasters risk in Dongshan Island were analyzed quantitatively usinglimited information and the information diffusion theory.It was found that the impact of typhoon,rainstorm and gale on Dongshan Island were relatively large,and it should be the main object of the subsequent study on the disaster prevention and reduction.(6)Using GIS,the method allows the elaboration of a diagnose of the connectivityof landscape ecosystems,on the basis of a previously defined set of ecological functional areas,and a computational cost-distance model which includes the barrier effect.Applying this model to Dongshan Island showed the ecological connectivity index(ECI)was low in 1994,improved by 2003,and decreased significantly by 2011.The results of the dynamic analysis of landscape structure showed lands used for cultivation and traffic corridors were the main landscape classes that caused the low observed ECI in 1994 and 2003;these tended to divide the landscape and cause fragmentation.Urbanized land and traffic corridors were the main landscape classes resulting in the low ECI in 2011,while forest and grassland had a high ECI.Trajectory analysis showed ECI tended to decrease in the northwestern and southeastern parts of Dongshan Island where forests form the main landscape class;coastal protection forest area were areas where ECI was becoming high in the northeastern part of Dongshan Island where cities and towns were concentrated with high human populations.Therefore,rapid urbanization has been the most important factor driving changes in landscape structure and patterns during the last 17 years on Dongshan Island.(7)The results showed that the spatial pattern of typhoon,rainstorm and gale disaster ecological risk appeared obvious change with time;overall,the risk value of low mountain area which is forested in the northwest of Dongshan Island was low,the risk values of northeastern area which is mainly towns and coastal area were high.It was found that human interference during the 17-year period has had both positive and negative effects.Long-term ecological construction in the low mountain area of northwestern Dongshan Island has made this area be forested and has reduced ecological vulnerability,and the overall ecological environment and anti-disaster capability in this area have improved.However,economic development in the form of tourism,aquaculture,and real estate,in conjunction with poor growth of the protective coastal forest,has increased the risk of town area and the coastal area of Dongshan Island.Then,spatial correlation analysis and statistical analysis methods were used to analyze ecological risk dynamics.The result showed that the ecological risks in Dongshan Island were rall positively correlated in space.The space distributions were not random,but tended to cluster;however,along with time,the cluster trend gradually decreased.Local spatial autocorrelation(LISA)of typhoon,rainstorm and gale ecological risks exhibited significant spatial and temporal differences.Based on LISA of typhoon ecological risk,low-low risk areas were found to be accumulated obviously in the northwest and the eastern coastal zone in 1994 and shrunk dramatically in 2003 and 201 1.Based on LISA ofrainstorm ecological risk,low-low risk areas were found to be accumulated obviously in the eastern coastal zone.However,in 2003 and 2011,low-low risk areas in the eastern coastal zone shrunk dramatically.According to LISA of gale ecological risk,low-low risk and high-high risk areas were found to be accumulated in the northwest zone and eastern coastal zone,respectively.A geostatistic analysis was conducted on the ecological risk space pattern,and the best fitting models were found to be all exponential models;non-structural factors such as various natural disasters and man-made activities play a leading role in the spatial distribution of ecological risk in Dongshan Island.By establishing the response relationships between regional eco-environment and hazard,the paper attempted to suggest a novel research approach and research thinking for regional disaster ecological risk assessment.This evaluation method can not only test the capacity of disaster bearing and anti-disaster of regional ecological system,but also provide scientific advice for disaster management and disaster prevention to regional government departments.(8)From the perspective of the supply and demand of ecosystem service,the paper analyzes the forest feature of service providing area(SPA)and the risk of service benefiting area(SBA)in Dongshan Island,and relates SPA and SBA based on the virtual watershed devided by the riversystem,considering the spatial connection between the supply and demand of ecosystem service,and finally assess the health status of SPA and SBA.The results showed that the health status of SPA and SBA were all general,which can reflect the ecosystem service to redistribution the rainfall provided by SPA was weak and the disaster risk of SBA may be high.Although the forest area in Dongshan Island increased year by year,the proportion of the forest in 2011 accounted for only 29.23%of the island,and the forest in Donshan Island,which is characterized by the single tree species,the simple structure,mainly pure and artificial forest and young trees,is easy to be affected by the disaster and weak protection when the disaster strikes.The health values of SBA were also generally low,which incicated that the capactiy to resist the disaster is fragile in Donshan Island.It is emphasized that the values in most of the northern island were low,which are the county and the main towns of Dongshan,because it is characterized by dense population,dense construction,high risk,small and scattered forest,and there are not only the rare large forest patches in crowded urban and towns,but also not good green corridors,to fail to form a good green space with the landscape and protective function.Therefore,to improve the health status of Dongshan Island,we need to plan and build a green system in urban areas.From the perspective of disaster mitigation,the study explores the ecological service function and the risk of human activities to determine the stability of regional ecological system when facing with the disaster,to seek new ideas and new methods for the diagnosis of regional ecosystem health status,and to provide a more targeted guidance for subsequent ecological construction and management. |
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