Evaluation And Prediction Of Ecosystem Service Value In Island Counties Of China Based On NDVI

Marine ecological civilization is a turning point in marine development in the new period.The report of the 19 th National Congress of the Communist Party of China clearly pointed out: "We must adhere to the overall planning of land and sea and accelerate the construction of a maritime power.".Islands are the convergence of terrestrial ecology and Marine ecology,as well as important Spaces and carriers for production,living and ecology.They play an important role and have special value in global maritime governance,economic and social development,and the protection of national maritime rights and interests.The sustainable supply of island ecosystem services is the basis of island sustainable utilization.Island county is a complex system of ecological space on land and sea,an important link between land and sea,and a key link in overall planning on land and sea.China's 12 island counties are located in important national strategic clusters such as the "One Belt and One Road" economic belt,the Yangtze River Delta economic circle and the Bohai Rim economic circle,playing an irreplaceable role in promoting the building of a maritime power and the implementation of major national development strategies and policies.In recent years,with the rapid economic and social development of islands and the rapid expansion of cities,the island ecosystem is facing serious threats,and the contradiction between the development and utilization of island resources and the protection of island ecological environment is becoming more and more acute.It is very important to carry out island ecological environment assessment and find out the status of island ecological environment for finding the balance between island ecological civilization construction and economic and social development.This study with 12 Chinese island county as the research object,based on the normalized difference vegetation index(NDVI),using the ecosystem services value(ESV)coefficient method,evaluated the 12 Chinese island county in 1990-2018 the change of ecosystem service value,at the same time using CA-Markov model to predict 2030 12 Chinese island county of ecosystem services value.The results are as follows:(1)From 1990 to 2018,the average NDVI of 12 island counties in China showed a continuous downward trend,with 2/3 of the islands having a particularly significant decrease in NDVI.Among them,Changhai County had the largest decline rate,reaching45.24 percent.The NDVI of Dinghai District,Putuo District,Yuhuan City and Nanao County increased.Among them,Yuhuan City had the largest growth rate of NDVI,reaching 37.71%.From the spatial perspective,the distribution of NDVI in each island county is significantly different,and the situation of each island within the island county is also greatly different.However,in general,the NDVI value in the central area of each island is generally higher,while the NDVI value in the edge area of each island is generally lower.(2)From 1990 to 2018,the total ESV of 12 island counties in China was 827 million US dollars,810 million US dollars,789 million US dollars and 821 million US dollars,showing a "V" shaped trend in general.ESV of 7 of the 12 island counties showed a downward trend,among which Changhai County had the largest decline,reaching 53.14%.The ESV of Chongming District,Nanao County and other five island counties increased,and the ESV of Nanao County increased the most,reaching 22.03%.The spatial distribution of ESV varies greatly among island counties,but in general,the ESV per unit area in the central area of the island is generally higher than that in the island marginal area.From the perspective of different land cover types,the ecosystem service value of forest is the highest,followed by grassland,and the ecosystem service value of buildings is the lowest.Forest is the primary factor affecting the vegetation coverage rate of islands.(3)In 2030,the total value of ESV in China's 12 island counties was 842 million US dollars,a total increase of 2.56% compared with 2018.From the perspective of different land cover types,the growth rate of ecosystem service value of forest was the largest,reaching 40.70%,followed by that of agricultural land,which was 15.91%.The ESV of grassland and barren land decreased by 67.89%,and that of barren land decreased by 62.63%.In terms of individual island counties,the ESV of Changhai County and Changdao County showed a downward trend,and that of Nanao County decreased the most,while that of Chongming District and Shengsi County increased to some extent,and that of Yuhua City increased the most.At the same time,this study believes that it is necessary to further protect and restore island vegetation,rationally develop and utilize island resources,effectively control the excessive expansion of island cities,and promote the modernization of China's island governance system and governance capacity.