若尔盖高原土地利用变化对生态系统服务价值的影响

运用GIS和遥感技术分析了若尔盖高原1990年、2000年和2005年的土地利用/覆盖特征, 在此基础上, 使用生态价值系数(C)计算出该区生态系统服务价值, 并使用敏感性指数(CS)对所选的C值进行验证. 结果表明, 该区域1990-2005年间生态系统服务价值从603.10?108元减少到586.07?108元, 共损失17.03?108元, 且损失量和损失幅度呈加速增加趋势; 该区域生态系统服务价值中, 废物处理价值最高, 水源涵养价值次之, 食物生产价值最低, 且各服务类型的价值均呈持续减小趋势; 若尔盖高原1990和2005年人均生态系统服务价值分别为38.93万元和27.03万元, 表明若尔盖高原由于人口增长和土地退化, 环境压力呈明显增大趋势. 湿地和草地退化是导致该区域生态系统服务价值减少的主要原因, 尤其是湿地退化. CS检验说明本文所选C值较为合理.

Impacts ofland use and cover changes on ecosystem service value in Zoige Plateau

Climate change and human activities in high-altitude, cold pasture areas with a fragile environment can cause land use changes that significantly affects ecosystem services and functions. Our study investigated changes in ecosystem services in response to land use change caused mainly by climate change and human activities in the Zoige Plateau, a region in the eastern fringe of the Tibetan Plateau with large areas of grassland and wetland. The objectives of our study were (1) to assign specific value coefficients for ecosystem services in the Zoige Plateau and determine whether these coefficient could be used to evaluate changes in ecosystem services in the study area; (2) to estimate changes in the ecosystem services value (ESV) resulting from land use changes caused by climate change and changing human activities; and (3) to provide information and advice to support regional sustainable development policies. We used remote sensing to evaluate land use changes, and then applied a fast method for evaluating ESV in 1990, 2000, and 2005. During the study period, the decrease in area and percentage of cover was greatest for high-cover grassland, followed by wetlands. The largest increase in area was for moderate-cover grassland, followed by low-cover grassland; the rate of increase was greatest for construction land, followed low-cover grassland. Among the nine land use categories, high-cover grasslands, woodlands, and wetlands showed a continuous decrease, but only the wetlands showed an accelerating rate of decrease. The total ESV dropped from 603.10?108 yuan in 1990 to 586.07?108 yuan in 2005, exhibiting an accelerated rate of decrease, mainly due to the degradation of wetlands and, to a lesser extent, high-cover grassland. Although the ESV of some land uses increased, these increases were too small to offset the decreases. Because wetlands had the highest value coefficient and covered a large area, the ESV of wetlands was the highest of the nine land use categories, accounting for about 48% of the total value. High- and moderate-cover grassland cover the largest total areas, and thus accounted for a proportionally large proportion of total ESV, even though the coefficients for these two land use types were much lower than that for wetland. Woodlands also generated high ESV due to its high value coefficient. The combined ESV for wetlands, high-cover grassland, woodland, and moderate-cover grassland accounted for about 93% of the total ESV, indicating that these categories, and especially wetlands, high-cover grassland, and woodland, provide the most important ecosystem services in the Zoige Plateau. In general, the changes in the contribution of each ecosystem function to the total ESV were small. The contribution of each ecosystem function to the overall ESV was greatest for waste treatment, followed by water supply; this likely resulted from the high ability of wetlands, high-cover grassland, and woodland to treat wastes and supply water. All nine types of service functions decreased, and but raw materials showed an accelerating rate of decrease from 1990 to 2005. The sensitivity analysis indicated that our estimates for the study area were robust despite uncertainties in the value coefficients. Our results also suggest that future land use planning should emphasize the protection of wetlands, high-cover grassland and woodland.