| As China's urbanization process continues to accelerate,many cities'ecosystems have shown a series of unhealthy symptoms,such as land degradation,biodiversity loss and decline in ecosystem services,which are posing threats to human health and living environment.The urban ecosystem health assessment approach applies to the needs in sustainable urban development and human health.Healthy urban ecosystem stands as an essential prerequisite for mankind to survive and develop.Maintaining the health of urban ecosystems and promoting the virtuous circle of urban ecosystems are subjects of importance both at home and abroad.Therefore,urban ecosystem health assessment is of great significance and has attracted a lot of attention.In terms of urban ecological health assessment,we conduct ecological health assessment on the whole city of Zhuhai from three aspects:landscape connectivity,ecosystem service evaluation,and ecosystem health assessment.At the same time,we also analyzed the accessibility of the green park in downtown Zhuhai.These four aspects of the study comprehensively reflect the urban ecological health status of Zhuhai City,and then understand the factors affecting the urban ecological health of Zhuhai City from the two research scales of the city and the central city.Based on the evaluation results,we put forward corresponding suggestions and formulate reasonable management measures to promote Zhuhai.It is of great significance to build an ecological city,coordinate the relationship between humans and the ecological environment,and realize the sustainable development of urban ecosystems.We used the Landsat TM/ETM remote sensing data of Zhuhai City in 1999,2005,2009 and 2013 and the Quick bird remote sensing data in 2003,2010 and 2015,and conducted research from two scales of the whole city and the central city.The research content is as follows:(1)Based on the graph theory method,the forest landscape connectivity in Zhuhai was evaluated,the two indicators of Probability of Connectivity(PC)and Integral Index of Connectivity(IIC)were selected to comprehensively reflected the changes in urban forest landscape connectivity and its influencing factors,we also selected the patch importance index dIIC to measure the importance of forest patches in Zhuhai,then identified the important forest patches at patch level,which is conducive to maintaining and enhancing urban forest landscapes;(2)Constructing Zhuhai City's ecosystem service value standard equivalent table,and revised it according to social and economic indicators,based on unit area value equivalent factor to calculate the ecosystem services value of Zhuhai City.Based on the changes in land use in Zhuhai City,the spatial and temporal changes in the ecosystem services value in Zhuhai City were explored.(3)We studied the ecosystem health of Zhuhai City by using the evaluation system consisting of vigor(V),organization(O),and resilience(R)and ecosystem service value(S)which widely used in urban ecosystem health assessment research.Based on the land use change data of Zhuhai City,the temporal and spatial changes of urban ecosystem health in Zhuhai City were explored.We also used the Geoda software to explore the relationship between ecosystem services and ecosystem health in Zhuhai.(4)We studied the accessibility of green space in the main urban area of Zhuhai City by establishing the database of urban road and urban green space,then classified the urban green space into four grades,and assessed the accessibility of the urban green space in the main urban area based on the Network Analysis model.Combined with data such as population density,multiple heart models were used to calculate the location of future urban parks.Research results in this paper indicated that:1.The landscape connectivity of urban forests landscape in Zhuhai City continues to fall and was reduced to a minimum in 2009.By identifying important patches in urban forest patches,which play an important role in maintaining urban forest landscape connectivity,we have found that during the urbanization process,the important grades and spatial distribution of forest patches have changed;the area of forest patches have a major impact on the connectivity of urban vegetation landscape:as distance thresholds increase,the importance of medium-sized patches rise significantly,and forest patches play a significant role in maintaining the connectivity of vegetation landscapes in the study area;important forest patches are pivotal to the maintaining and improvement of landscape connectivity,and forms an important factor in building urban ecological corridors and improving the level of urban ecological health.2.Research on urban ecosystem service of Zhuhai City showed that the overall service value of the city's urban ecosystem services had been on the decline during urbanization,and the ecosystem service function has declined.By 2013,the ecosystem services value of Zhuhai City mainly showed that waste treatment functions and hydrological regulation functions accounted for 53.98%of the total value,while the ecosystem services value such as food production,raw material production,and gas regulation accounted for only 11.29%.There existed a certain imbalance in the current ecosystem service function.In the future ecological planning and construction process in Zhuhai City,it is necessary to consider strengthening the ecosystem service function that is relatively small,and prioritizing the provision of relativelly small ecosystem service functions when adjusting the urban land use structure.3.The overall health level of urban ecosystem shows a downward trend,the area of ill-being areas increased significantly,and the area in healthy state decreased year by year.By 2013,the areas of morbidity,unhealthy,critical state,healthy and healthy accounted for 28.29%,15.96%,9.91%,29.71%and 16.11%,respectively.It can be seen that urbanization has seriously affected the land health of Zhuhai City.The area of the diseased area has increased significantly,accounting for almost one-third of the total area of the study area.Spatial correlation analysis of ecosystem service and ecosystem health showed that the synergy effect is dominant in their relationship.4.The analysis of the accessibility of urban parks in the main urban area of Zhuhai showed that the overall accessibility of urban green spaces in Zhuhai's grades one,two and three city parks need to be further improved,and the service scope is unevenly distributed.The service efficiency and population service efficiency of the fourth-level urban parks were 58.95%and 60.62%,respectively.The location of the new urban park through a multi-center model took into account the population density distribution of Zhuhai and the accessibility of the existing urban green space.In future urban planning,we should pay more attention to the actual needs of the residents and make use of different levels of green space accessibility to carry out the future ecological construction in cities.Research results in this paper will provide support for deciding future ecological construction of main urban area and sustainable urban development of Zhuhai City. |
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