Study On Forest Ecological Carrying Capacity Evaluation In Hangzhou Based On GIS And RS

With the rapid development of economy and technology,problems such as climate warming,resource shortage and ecological environment destruction have emerged,which cause great impact on human life.Clarifying the current situation of resources and environment,and evaluating the environmental and resource capacity are the prerequisites for sustainable development of society.As the largest ecosystem on land,forest ecosystem has multiple ecological functions such as carbon sequestration and oxygen release,climate regulation,etc.Forest ecosystem is an important barrier to maintain ecological security on the earth and plays an irreplaceable role in the survival and development of mankind.At the same time,as the largest carbon reservoir in the ecosystem,forest ecosystem contributes about 80% of carbon sequestration,which has an inestimable role in achieving the goal of carbon peak and carbon neutrality.Taking the sustainable development theory as instruction,firstly,study clarifies the connotation of forest ecological carrying capacity,and initially constructs the forest ecological carrying capacity evaluation index system based on its connotation.Secondly,combining with forest resource survey and socio-economic survey,study uses geographic information system(GIS)and remote sensing(RS)technology to dig ecological information and determine the actual value of each index.The reference value of the index is determined combined with local development goals,planning and relevant industry standards,etc.The standard ratio method is used to standardize the indicators to obtain the evaluation index value.Then,the evaluation index screening method about correlation is adopted,which based on ill-condition index and information substitutability.The index weights are determined according to expert scoring and hierarchical analysis.The comprehensive index method is used to calculate the comprehensive evaluation value of forest ecological carrying capacity before and after index screening.Based on the absolute value of relative deviation of forest ecological carrying capacity evaluation value before and after index screening,the feasibility of index screening can be judged and the final evaluation index system is determined.Finally,the evaluation of forest ecological carrying capacity in Hangzhou is carried out,the spatial distribution characteristics and causes of forest ecological carrying capacity are analyzed,and the countermeasures and suggestions to improve the forest ecological carrying capacity are proposed.The main research contents and findings are summarized as follows.(1)Connotation definition of forest ecological carrying capacity and preliminary construction of evaluation index system.Based on the previous studies,the connotation of forest ecological carrying capacity in the study is: the maximum human activities that can be maintained by the self-sustaining capacity,self-regulating capacity,resource supply capacity and environmental carrying capacity of the forest ecosystem in a certain period of time and in a certain area.Therefore,the forest ecological carrying capacity evaluation index system should include four aspects: forest ecological resilience,forest resource supply capacity,forest ecological and environmental carrying capacity,and human activity potential.(2)Forest ecological information mining in Hangzhou based on GIS and RS.Use GIS to obtain the topography,meteorology,other natural geographic information and ecological environment service function of Hangzhou such as forest carbon sequestration and oxygen release,water conservation and soil conservation.Based on the remote sensing images of the domestic satellite GF-6,the random forest model with the highest accuracy is used to invert the forest canopy density and forest volume in Hangzhou after comparing the estimation accuracy of multiple stepwise regression,BP neural network and random forest using sample data,which provides data for the forest ecological carrying capacity evaluation in Hangzhou.The method of using GIS and RS to obtain forest information on a large scale quickly and efficiently is explored to provide a technical path to improve the timeliness of data and reduce the cost for forest resource survey.Also it compensates for the disadvantages of the traditional methods of obtaining forest ecological information,which are time-consuming and complicated.(3)Screening and determination of forest ecological carrying capacity evaluation index system in Hangzhou.The evaluation indicators are screened based on illcondition index and information substitutability,and then the original 20 indicators are screened to 16 indicators.The absolute value of relative deviation of forest ecological carrying capacity evaluation value before and after index screening is less than 5%,so the screening of indicators is feasible.The screened index system includes: slope,humus thickness,naturalness and community structure,which reflect the forest ecological resilience;forest coverage,forest stock per unit area,forest canopy density,the proportion of young and middle aged forests and the proportion of public forests,which reflect the forest ecological and environmental carrying capacity;carbon sequestration and oxygen release function,water conservation function,soil conservation function and forest health level,which reflect the carrying capacity of forest ecological environment;GDP growth rate,per-capita forest area and the proportion of commercial forests,which reflect the human activity potential.The screening of indicators reduces the complexity of evaluation and provides references for the simplification of forest ecological carrying capacity evaluation in the future.(4)Evaluation and analysis of forest ecological carrying capacity in Hangzhou.According to the forest ecological carrying capacity evaluation in Hangzhou based on the screened 16 indicators,the forest in Hangzhou is in a strong carrying state,and the forest ecological carrying capacity in each county(city and district)ranked from high to low is: Chun’an County,Lin’an District,Jiande City,Tonglu County,Fuyang District,Yuhang District,Central City and Xiaoshan District.The forests in the first five regions are in strong carrying states,while the forests in the latter three regions are in medium carrying states.And the forest ecological carrying capacity of Chun’an County,Lin’an District,Jiande City and Tonglu County exceeds the overall level of Hangzhou,while the forest ecological carrying capacity of Fuyang District,Yuhang District,Central City and Xiaoshan District are lower than the overall level of Hangzhou.The human activity potential layer is the main reason for the difference of forest ecological carrying capacity of each county(city and district),and the evaluation results are consistent with the main-function of each region.Finally,based on the above evaluation results,countermeasures and suggestions for improving the forest ecological carrying capacity in Hangzhou are proposed in a targeted manner from the perspective of resource supply capacity,ecological and environmental carrying capacity and human activity potential.