Research On Relationships Between Supply And Demand Of Ecosystem Services In Guangdong-Hong Kong-Macao Greater Bay Area Based On Ecosystem Services Flow

The Guangdong-Hongkong-Macao Greater Bay Area（hereafter GBA）is one of the city clusters with the most vital economic vitality and the highest urbanization level in China.However,cities’ rapid development depletes many ecosystem services and encroaches a significant quantity of ecological land.The potential productivity of ecosystem services is greatly affected.With the significant improvement of material living conditions,human demand for fresh air,clean water,and beautiful green land are growing,and the changes in the relation between supply and demand of ecosystem services in terms of balance have emerged.Studying the relation between the supply and demand of natural ecosystem services is conducive to protecting the ecological environment.It maximizes the effectiveness of ecosystem services,which has important practical significance for realizing sustainable development and the urban ecosystem healthy operation.This study sorts out the development of theories relevant to ecosystem services,construct the evaluation model of ecosystem service flows,and use five periods of multisource data from 2000,2005,2010,2015,and 2020 to calculate the path and flow of ecosystem service flows by entropy method.Meanwhile,through the internal connection between ecosystem service flows and supply-demand relation,the research framework of the supply-demand relationships of ecosystem services is constructed to study the relation between supply-demand of the ecosystem services the periodic evolution characteristics of stability of the system in GBA in the years from 2000 to 2020.The risk of supply and demand structure is also assessed.The study also tends to calculate the ecosystem service flows of 11 cities to find out the fundamental characteristics and internal distinctions.The main conclusions are as follows:First of all,the service flow-based quantitative research method is suitable for studying the relationships between the supply and demand of ecosystem services.The thesis uses the entropy method to calculate the ecosystem entropy and service ecosystem flows,builds a risk rating evaluation framework of supply-demand structure based on the results calculated,and clarifies the research thinking of ecosystem service flows and its relationships between supply and demand.The final evaluation result objectively reveals the changes in the ecosystem stability of the GBA and the characteristics of the relationships between supply and demand in the past 20 years.The method is relatively novel,with scientificness and reproducibility.The second,overall,the stability of the ecosystem in 2020 is worse than that in 2000 but slightly better than that in 2005,2010,2015,which shows the stability of the ecosystem has slightly improved recently.Third,the supply and demand structure of ecosystem services in 2020 tends to be safe.The main factors causing the unsafe structure of supply and demand are the reduction of forest land area,the increase in urban pollutant emissions,and the housing construction area.Fourth,the GBA ecosystem can restore system stability while maintaining a high supply of services.It proves that the ecosystem has a solid ecological carrying capacity.Fifth,the differences in the supply and demand of ecosystem services between cities are mainly restricted by the socio-economic structure.The last,except for the dangerous risk level of supply and demand structure in Dongguan,the rest of the cities are all safe.However,there is an increasing trend of ecological risk（except for Shenzhen）.It is necessary to further optimize the supply and demand structure and adjust the industrial layout to reduce potential ecological risks.In the end,the research provides suggestions and strategies for the future development of the region from the perspectives of ecological protection,service development,supply-demand relationships,planning,and design.