| Dongting Lake is one of the most representative wetland ecosystems in China.Changes of ecological environment in Dongting Lake wetland have caught attention for a long time.It is an important task of scientists and government departments at all levels to be addressed of how to understand the ecological service function and the law of spatial and temporal variation in Dongting Lake wetland,rationally evaluating its economic value and how to carry out the realistic protection work.Based on basic data and in-depth research,using functional differentiation principle,this paper has taken the Dongting Lake wetland ecosystem as the object of the research and built an evaluation system of the ecological service function of Dongting Lake wetland ecosystem which consisting of four levels of indicators namely service type,service projects,service index and the contents of index;The system framework of the overall function of Dongting Lake ecosystem,consists of nine function:product supply,support services,social services regulation three categories,regulating water,biodiversity maintenance,water purification,product supply,carbon sequestration,nutrient cycling,soil conservation,microclimate regulation and social service;This paper has systematically described the process of lake ecosystems' changes of Dongting lake wetland ecosystem in the past 60 years,making use of the above indicator system framework and relevant data.Besides,using the data in 2010,this paper analyzes the structure of wetland ecosystem services and features,exploring the coupling relationship between wetland ecological processes and ecosystem services,and the effect of nature driving force and human disturbance force on service function of Dongting lake wetland ecosystem.This paper has conducted a comprehensive and systematic analysis to the service function of Dongting Lake wetland ecosystem,making use of market assessment,implied market assessment and simulation market assessment.And it has also made an evaluation to the ecological value of Dongting Lake wetland using the method of market value,replacement cost and willingness to pay etc.Three categories of Dongting Lake wetland ecosystem's ecological functions and the evaluation results of their economic value are as follows:1.Spatial and temporal changes of main ecological functions of wetland in Dongting Lake.Nearly 60 years,wetland area has decreased and wetland impoundments function has declined.Wetland area has decreased from 4350 km2 in 1949 to 2638 km2 in 2010,only taking portion of 60.64%in 1949.In2010,the capacity of water storage is 135.33 × 108 m3,taking portion of58.70%in 1949 of 293 × 108 m3.Biological resources have decreased and biodiversity has reduced.In 2010 aquatic vegetation coverage rate,narrowly aquatic species,association types has reduced by 71.6%,31.7%and 36.9%over the number in 1970,aquatic catch in 2010 compared with 1998 has decreased 58.74%.In recent years,the number of communities and migratory birds wintering populations has dropped by 20%to 30%than the number in the 1950s.2.Productivity levels in Dongting Lake wetland ecosystems(output physical quantity).In 2010,Dongting Lake wetland ecosystem in the output supply function area include:wetland meadow plant communities,aquatic plant communities and plant trees net productivity is 327 × 104,182 × 104,330 × 104t/a;fiber plants provide food,wild vegetables,forage,green manure and fish respectively is 135.22 × 104,2.87 × 104,20.34 × 104,15.08 ×104 and 21245.3t/a.In support of the regulatory function,the absorption of atmospheric carbon dioxide is 617.21×104 t/a,and release oxygen is 450.61× 104 t/a;the amount of the absorb nutrients by plants from the soil is 4.89 x 104 t/a,and the return of soil nutrients is 8516.8 t/a;purified N,P and COD is 58463t,9236t and 220567 t.Purification of organic pollutants,inorganic pollutants,heavy metals are 111.17 t,471.82 t and 62.90 t;daily average temperature in wetland residential is lower 1.2? than the surrounding area not belonging to the Dongting lake wetland areas;the amount of water vapor is 5.20 × 108 t/a more than in the surrounding area annual;regulating 135.33× 108 m3 of water.And control 839.81 hm2 of soil(silt stagnation reclamation).Output in the social service functions include:reception domestic and foreign 3145 ×104 passengers;maritime passenger traffic in 2010 is 715 × 104 people · times;maritime passenger turnover is 15394 ×104 people·km;water transport volume is 9135 × 104 t;freight turnover is 247.10 × 108 t · km.3.The total value of ecosystem services and its components in Dongting Lake wetland.In 2010,the total ecological service value of Dongting Lake wetland has reached 2564245 × 104 yuan.Among them,the value of goods and services provided directly is 102168 × 104 yuan,and adjustable support service value is 1566308 × 104 yuan;social services function service value is 895759 × 104 yuan.And they have accounted for 3.99%,61.08%and 34.93%of the total service value respectively.4.Service value of Dongting Lake wetland ecosystem in the use and non-use value.After calculation,the use value in 2010 of Dongting Lake wetland ecosystem services is 985818 × 104 yuan.Among them,the direct value is 102168 × 104 yuan and indirect value is 883650 × 104 yuan,accounting for the total service value of 3.99%and 34.46%respectively,and accounting 10.36 percent and 89.64 percent of use value.Non-use value is 1578427 × 104 yuan.Among them,existence value is 1566318 × 104 yuan,and choose use value is 12109 × 104 yuan.And they have accounted for 61.08%and 0.47%of the total service value,and 99.23%?0.77%of non-use value.5.Value of production services and ecosystem services in Dongting Lake wetland ecosystem service value.After calculation,the value of services in Dongting Lake wetland ecosystems provided by the system productivity(production services value)is 102168 × 104 yuan in 2010,3.99%of the total service value;the value of ecosystem services by the structure and function of the ecosystem itself generate 2462077 × 104 yuan,accounting for 96.01 percent of the total value of the service.The ration between the product service value and the ecological service value is about 1:25.8.6.Core services of Dongting Lake wetland ecosystems.From the results of the assessment estimates,we can know that the current core services of Dongting Lake wetland ecosystems is regulating and storing water,recreation and leisure,regulate atmospheric composition,and they have accounted for 29.90%,26.52%and 13.59%of the total value of service respectively.Three species service value accounted for 70.01%of the total value of the services.This is determined by structural characteristics of region position of Dongting Lake wetland,rich tourism resources and tourism industry,and the local governments vigorously developing tourism industry.However,with the development of tourism,recreation and leisure functions may be more and more prominent in the future.Other services will be secondary,while which can not be ignored.It is precisely because the existence of these services,that Dongting Lake wetland ecosystems provide a large number of raw materials for the industrial and agricultural production,biological provide habitat,clean water environment wetland ecosystems,improving of the climate of wetland ecosystems to humans a good ecological environment to live and work.This paper has only chosen the objective criteria and valuation basis when assessing the economic value of the ecological service function.It has only chosen the values that can directly benefit human beings so as to avoid double count and estimate,to make the evaluation result more realistic to reflect the economic significance of the wetland ecosystem services in Dongting Lake,and to provide a more reliable scientific basis for the management and decision-making of Dongting Lake wetland.Dongting Lake is now facing a series of problems such as area shrinking,functional decline,frequent floods,destruction of biological resources and decrease of biological diversity.In order to restore and improve the service function of Dongting Lake wetland ecosystem,we believe that it is a must to unify the understanding of the protection of Dongting Lake wetland,well maintaining the system between Yangtze River and Dongting Lake,reasonably adjusting the water resources and comprehensively increasing the capacity of flood control.Thus,we can promote the benign balance of wetland ecosystem,harmonize the structure and function of Dongting Lake wetland ecosystem effectively,and strengthen the standardized management of Dongting lake area.At this stage,we should focus on curbing the area shrinking of Dongting Lake,improving the function area planning of Dongting Lake wetland,respecting for the laws of nature,reducing human interference.Only by doing these can we improve the wetland ecosystem services and the wetland ecosystem service benefits system. |
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