Study On Spatial Optimization Of The Natural Protected Area In Northern Guangdong Based On Ecosystem Integrity Evaluation

The building of nature reserves is an effective means of protecting ecosystems and maintaining resources and biodiversity.Existing nature reserves suffer from fragmentation,regional crossover and protection gaps.With the release of the Guidance on the Establishment of a Nature Reserve System with National Parks as the Mainstay,China has entered a critical period of transition between the old and new nature reserve systems,and the construction and optimisation of the nature reserve system has become a major strategic objective in the construction of ecological civilisation in China.Ecosystem integrity is an important factor in maintaining ecosystem function and ecosystem stability,and has become a core objective and an important indicator of ecological protection,which is one of the important bases for spatial optimisation of nature reserves.The northern part of Guangdong has superior ecological resources and is a key node in the national ecological security institutional framework.In this study,27 administrative counties in northern Guangdong were selected as the study area based on the importance of ecological functions,biodiversity richness and water conservation,and a framework for evaluating the integrity of the ecosystem was constructed based on three major criteria:composition-structure-function,and a comprehensive evaluation of the northern Guangdong region was carried out.The spatial optimisation of protected areas in northern Guangdong was further proposed.The main findings of this study were as follows:(1)Based on the "composition-structure-function" framework,seven indicators were selected for compositional integrity,including solar radiation,average monthly temperature of the coldest month,average monthly temperature of the hottest month,rainfall,soil type,distribution of key protected species and woodland type.In structural integrity,three indicators were selected: leaf area index,landscape fragmentation and distribution of carnivore species;in functional integrity,three indicators were selected: nitrogen nutrient use efficiency,phosphorus nutrient use efficiency and net primary productivity.Hierarchical analysis and the Delphi method were used to obtain the weights of the indicators,and finally a set of evaluation framework for ecosystem integrity was constructed for northern Guangdong.(2)The evaluation results of ecosystem integrity were obtained by standardizing the indicators and calculating the integrity evaluation index.The overall ecosystem integrity of northern Guangdong is good,with an integrity index ranging from 0.204 to 1 and an average value of 0.562.0.605)are mainly located in the northern Guangdong foothills such as Guangning and Fengkai counties.Among them,the largest contiguous area of high ecosystem integrity was found in Luyuan Yao Autonomous County,and the highest ecosystem integrity index was found in Lianping County and southern Yingde County.(3)The overlay analysis method and the nuclear density analysis method were used to sort out the profile of the current nature reserves in northern Guangdong,and the principles and paths for the spatial optimization of nature reserves were determined by combining the evaluation results of ecosystem integrity.By screening out important areas for ecosystem protection,16 proposed expansions of existing nature reserves and three proposed new nature reserves were identified on the conservation vacant areas,and finally a set of spatial optimization schemes for nature reserves in northern Guangdong was proposed.In summary,this study provides a new idea for the spatial optimization of nature reserves based on ecosystem integrity assessment,thus strongly supporting the construction of the nature reserve system in Guangdong Province.In the future,the spatial optimization study of nature reserves can be further improved by refining the selection of evaluation indicators for aquatic and terrestrial ecosystems,refining the resolution of key areas,and combining the evaluation perspectives of ecosystem service value and ecological vulnerability,thus providing case references for the smooth promotion of the integration and optimization of nature reserves in China.