Dynamic Evaluation of Natural Ecosystem Service in Hainan Island

There are rich and diverse natural ecosystems in Hainan Island. They are not only the support of the ecological province construction of Hainan, but also of great importance to the ecological security of Hainan Island. Taking Hainan Island as the survey region, the type and distribution of natural ecosystem are got by using RS, GIS and GPS technology. Natural ecosystem in Hainan Island is classified into four types: forest, wetland, freshwater and grassland. Based on the function evaluation system of natural ecosystem service, the economic value of services provided by those four natural ecosystem types in the decade is dynamically assessed by using relevant theories and research methods of ecological economics. The carefully chosen valuation techniques also get some improvements to suit the specialty of natural ecosystem in Hainan Island. According to the results, the total area of natural ecosystems in Hainan Island shows a decreasing trend from 1998 to 2008, especially from 1998 to 2004, during which time the total area of natural ecosystems plummeted by 3281.19 km 2 . Among four kinds of natural ecosystems, the area of forest and grassland significantly reduce, and the reducing rates reach 20.98% and 91.63% respectively. The total value of natural ecosystem services in 1998, 2004 and 2008 were 310 579 million, 223 261 million and 219 729 million respectively, which shows a decreasing trend as well. The value of forest ecosystem service accounts for more than 80% of the total value of natural ecosystem services, following by the value of freshwater ecosystem service, which takes about 15% of the total value in 2008. Although the total value is decreasing and the reduction rate of the value is much less than the GDP growth rate, the development state of the whole natural ecosystem in Hainan province is not very hopeful. Affected by regional climatic environment and human social activities, values of various natural ecosystem services present different dynamic changing trends. Because of large-scale decrease of natural forests, the value of forest ecosystem service lowers significantly from 239 814 million to 183 519 million,especially during the years 2004-2008. The value of grassland ecosystem service shows the same trend as forest ecosystem, while the values of wetland and freshwater ecosystem services are slightly increasing. Regional climatic environment and human social activities not only affect the quantity and quality of ecosystems, but also directly affect the performance of the ecosystem services, such as rainfall, etc. Long-term dynamic evaluation of natural ecosystem service has important scientific significance on realizing the dynamic monitoring of the value of natural ecosystem service in Hainan Island and strengthening construction of ecological environment protection and macro policy-making by governments at all levels.