基于LUCC的兰州城市生态系统服务价值动态分析

Dynamic analysis of ecosystem service value based on land use/cover change in Lanzhou City

生态脆弱型城市生态系统服务价值评估是保育和合理开发城市生态系统的重要基础。构建典型生态脆弱型城市生态服务价值评估模型,以兰州城市生态系统为例,运用GIS和遥感技术分析LUCC特征,计算1989年、1999年和2009年6类主要土地利用类型的9项生态系统服务项目价值。结果表明：1）20a间兰州市耕地面积减少幅度最大为42.54%,水体湿地、草地次之。总价值呈现出先增加后减少的趋势,1999年兰州城市生态服务价值最大为4.4377×10~8元,2009年生态服务价值是1989年的1.5倍。2）土壤形成与保护服务功能价值占总价值的比例最高约20%,食物生产和娱乐文化服务功能价值占总价值比例较低为3.7%、3.4%,气体调节、娱乐文化和原材料生态服务价值增幅最大。3）各年份林地、草地、耕地和水体湿地生态服务价值均为总价值构成的主要部分,林地和草地生态系统对总服务价值的贡献率最高。城市扩张中应注重林草地的保育与合理规划。4）价值系数敏感性检验表明,生态系统服务价值对其缺乏弹性,模型能够合理评估该区域生态服务价值波动。

Quantitative evaluation of the services provided by fragile urban ecosystem is an important foundation for protecting and developing urban ecosystem. Geographic information system and remote sensing technology were used to analyze the characteristics of land use/cover change. The evaluation model for the fragile urban ecosystem services was constructed to estimate the ecosystem value of Lanzhou City in 1989, 1999 and 2009. The results showed are as follows. 1） The cropland was reduced the most by 42.54% while the water/wetland and the grassland were reduced by 21.32% and 19.32%, respectively, from 1989 to 2009. The total value of the urban ecosystem service increased from 1989 to 1999 reaching the highest value of 4.4377×10~8 RMB then decreased from 1999 to 2009. During the entire period, the total ecosystem service value increased 50%. 2） Of the different types of ecosystem services, the value of soil formation and retention was the highest at 20% of the total value, while recreation/culture value and food value were the lowest ones at 3.4% and 3.7%, respectively. The types of ecosystem services with the most percentage of value increases were gas regulation, recreation/culture and raw materials during the period studied. 3） The main components of ecosystem service value came from woodland, grassland, cropland and water/wetland ecosystems, of which, woodland and grassland ecosystems contributed the most to the total value. Thus, much attention should be paid in conservation and rational planning of woodland and grassland in the process of Lanzhou urban expansion. 4） The sensitivity coefficients of ecosystem service value for each land use type were less than 1, indicating that the ecosystem service value lacked flexibility on its index. Therefore, the dynamic of ecosystem service value in Lanzhou City can be evaluated reasonably using this model.