和田河流域天然胡杨林的生态服务价值评估

Assessment of ecological service values for native Populus euphratica forest in Khotan watershed

胡杨林是干旱或荒漠地区的一种特有植被,它的生存对改善干旱或荒漠地区的生态环境有重要作用。以分布于塔里木河三源流之一的和田河流域的天然胡杨林为研究对象,使用影子工程法、机会成本法、水量平衡法、市场价值法等方法,评价了天然胡杨林在有机质生产、气候调节、土壤的形成与保护等七大类间接生态服务价值和木材产品、工业原料等2类直接生态服务价值,并分析计算评估结果。结果表明:在和田河流域,面积为3.184万hm2的天然胡杨林生态系统服务价值平均为6.72亿元/a,为整个和田地区2002年GNP的19.02%。这一结果充分说明和田河流域天然胡杨林在减缓自然灾害、维护生态安全和社会经济发展中的不可替代的天然屏障和保障作用,对和田绿洲乃至塔里木河流域综合治理的全局都是极为重要的。

Riparian Popuhts euphratica forest is endemic to the arid and desert areas of China. It plays an important role in maintaining the health and stability of arid ecosystems. The aim of this paper is to better the relationship between the P. euphratica forest system and people and to offer a solid basis for scientific management and sustainable utilization of the P.euphratica forest. In this paper, we take P. euphratica forest occurring in the Khotan watershed as a case study and collected the related data through filed survey. Using these data, we assess the direct and indirect ecological service values （ESVs） of the P. euphratica forest system, using some mathematic and physical methods and economic methods, such as market pricing method, opportunity cost method, water quantity equation method, and shadow project method. The indirect ESVs are the production of organic matter, climate regulation, soil formation and protection, water regulation, environment purification, biodiversity conservation, and the value of recreation and culture. The direct ESVs are timber production and industrial raw material. The indirect ESVs are the production of organic matter, climate regulation, soil formation and protection, water regulation, environment purification, biodiversity conservation, and the value of recreation and culture. The direct ESVs are timber production and industrial raw material. The indirect ESVs are the production of organic matter, climate regulation, soil formation and protection, water regulation, environment purification, biodiversity conservation, and the value of recreation and culture. The direct ESVs are timber production and industrial raw material. Results from this study showed that the average ESV of the P. euphratica forest system, covering an area of 3.184×104 hm^2 in the study region, was 67 million Yuan per year, which accounted for 19.0% of the Khotan region＇s gross national production in 2002. Of the total forest＇s ESV, the annual value of organic matter production was 19.2 million Yuan, which accounted for 28.7%, followed by biodiversity＇ s conservation value being 16.4 million Yuan per year, which accounted for 24.5%, and environmental purification value being 12.3 million Yuan per year, which accounted for 18.4 %. Moreover, the annual values of climate regulation and soil formation and protection are also significant, which are 7.9 and 7.0 million Yuan and accounted for 11.7% and 10.5% of the total ESV, respectively. For the direct value of the P. euphratica forest system, the value of timber product is found to be 7.6 million Yuan per year and accounted for only 3.3 % of the total ESV, which was different from people＇ s normal thinking . Our results also showed that the economic value is much higher than its investment, and the indirect value is several times higher than the direct value. Thus, we should pay much attention to developing forest＇ s management practices in river origins, as in the case of the P. the forest＇s ecosystem service functions in euphratica forest ecosystem in the Khotan＇ s watershed. We hope that our study could stimulate more investigation on the assessment of local P. euphratica forests in order to have a better understanding of ecological functions of riparian forests in the arid and desert regions of northwest China.