甘肃白龙江流域生态系统粮食生产服务价值时空分异

Assessment of ecosystem food production and its spatiotemporal heterogeneity in the Bailong River Watershed,Gansu

粮食生产服务是区域生态系统主要的服务功能之一,也是人类福祉和社会发展的基础,受自然环境和社会经济发展而不断变化。然而,目前国内外尚缺乏统一的生态系统服务价值的时空动态评估方法,尤其是在脆弱的山区过渡带区域。以灾害频发的脆弱生态过渡带——甘肃白龙江流域为例,尝试引入自然环境和人文社会要素对区域生态系统生产服务经济价值进行系数调整与修正,构建生态系统服务价值的计量评估模型,测算流域内生态系统生产服务价值并分析其时空差异性。结果表明:(1)1990—2010年间白龙江流域耕地面积波动起伏较大,但流域内生态系统生产服务价值却表现出持续上升的趋势,至2010年平均生产服务价值达186.74万元。生态系统生产服务价值空间格局变化不大,其高产区约占42.4%以上,主要分布在宕昌县西北部的岷江两岸和舟曲城关镇—武都汉王镇的白龙江两岸及其以北区域。(2)方法改进后,白龙江流域生产经济价值相对减小(172.74万元),间接反映了研究区内滑坡、泥石流等自然灾害和区位人文社会要素对生产经济价值的影响,更符合流域的实际情况。

Terrestrial ecosystems function supply food （e.g. grains, vegetables）, maintain diversity, and prevent environmental contamination. Thus, it is important to human well-being. Food production is vital for the sustainable development of human populations, and its dynamic spatiotemporal factors are closely related to spatial geographical heterogeneity and social development. However, there are only a few studies on the universal dynamic evaluation methods for ecosystem function used at the regional scale, especially in the fragile mountains of China. Bailong River Watershed （BRW） is located in the transitional ecotone along the Tibet Plateau, Loess Plateau and Qinba Mountains, and it was selected to analyze the spatiotemporal heterogeneity of ecosystem food production. Based on a field survey employing land use data, model simulations, and GIS spatial analysis, the ecological conditions and socio-economical factors were used to revise the previously held dogma which put forward by Costanza in 1997. Specifically, sources of hazards reflected the differences in ecological conditions. The resource scarcity theory and the willingness to pay were used to revise and calculate the economic developmental coefficient. A dynamic evaluation model was constructed with the above corrections method and applied for ecosystem food production services assessment in the Bailong river watershed during 1990-2010. In addition, spatiotemporal heterogeneity and food production were analyzed by ArcGIS 9.3. The results indicated that the supply of cropland distributed in the river valley and bank area of BRW, hill slopes, low mountain regions and decreased. The area of instable cropland and the index of social progress increased. In the period of 1990-2010, ecosystem food production value increased. The mean value of food production was 1.8674 million Yuan in 2010. In addition, the spatial distribution pattern change of food production value was not obvious. Land accounting for high yield of food production value was 42.4% of the total area, which was mainly distributed in the valleys of BRW between Zhouqu and Hanwang town, the northwestern part of Tanchang County. The low-yield areas of food production distributed in the national nature reserve and forest. Our data change how the value of China＇s terrestrial ecosystem was previously defined on a national to regional scale. Compared with a previous evaluation model, the change in food production was smaller using our method, and its spatial pattern was a better fit to the natural system of the Bailong river watershed. These data indicate that natural hazards （such as landslides and debris） and human activities affected food production and its value.