青藏高原东缘典型流域生态系统服务的地形梯度效应——以岷江上游为例

TOPOGRAPHIC GRADIENT EFFECTS OF TYPICAL WATERSHED ECOSYSTEM SERVICES IN THE EASTERN TIBETAN PLATEAU—— A CASE STUDY OF THE UPPER REACHES OF MINJIANG RIVER

山地生态系统受地形因素影响在垂向上呈现出明显的空间分异特征,厘清山地生态系统服务的空间分异特征是区域土地利用和生态系统管理的基础。以青藏高原东缘典型流域岷江上游为研究区,将2000、2005、2010年土地利用数据及DEM数据作为数据源,运用地形位指数、相对变化率和敏感性系数,研究土地利用变化下的生态系统服务价值的地形梯度效应。结果表明:(1)岷江上游土地利用类型以林地和草地为主,约占总面积的60%和30%;2000~2010年,1~4级地形位上除未利用地外的其他土地利用类型分布指数变化较为明显,林地和耕地不断降低,草地、水域和建设用地不断升高。(2)研究期内岷江上游生态系统服务价值总量和各类型生态系统服务的价值随地形位的升高均呈倒V形变化;2000~2010年,研究区1~12级地形位上生态系统服务价值呈增加趋势,13~20级地形位上呈减小趋势。(3)2000~2010年,各地形位上生态系统服务价值变化趋势与研究区一致;除1级地形位上生态系统服务价值变化幅度略高于研究区外,2~20级地形位上的变化幅度与研究区基本一致。(4)研究区各土地利用类型的单位面积生态系统服务价值敏感性系数均小于1,单位面积生态系统服务价值的变化缺乏弹性,研究结果可信;2000~2010年各地形位上水域、草地和荒漠敏感性系数不断上升,林地和耕地敏感性系数不断下降。通过对土地利用变化驱动下的生态系统服务价值的地形梯度效应进行定量测度,明晰了生态系统服务价值随地形梯度变化所呈现的空间分异规律及其变化特征,为保护区域生态系统,合理利用土地资源提供理论依据。

The spatial characteristics of mountain ecosystems are affected by terrain factors. Clarifying the spatial differentiation characteristics of mountain ecosystem services is the basis of regional land use and ecosystem management. This study took the Upper Reaches of the Minjiang River（ URMR） as study areas. The terrain gradient characteristics of ecosystem service value under land-use change were identified using terrain index,relative rate of change and sensitivity coefficient based on land-use data and DEM data. The results showed that：（ 1） The land-use types in the URMR were dominated by woodland and grassland,which accounted for 60% and30% of the total area,respectively. During 2000 to 2010,the change of terrain index was obvious in 1-4 terrain areas.（ 2） The total value of ecosystem services and the value of individual ecosystem services in the URMR showed an inverted V-shape change with the increase of topographic area. During 2000 to 2010,the ecosystem service value（ ESV） increased in 1-12 terrain areas and reduced in 13-20.（ 3） During 2000 to 2010,the trend of ESV in each terrain was consistent with that of the study area. In 1 terrain area,the change of ESV in the topographic level was slightly higher than that of the study area. In 2-20 terrain areas,the change was nearly consistent with the study area.（ 4） The sensitivity coefficient of the ESV in per unit area of land-use types in the study area was less than 1 and the change of the ESV in per unit area was lack of flexibility. It showed that the results were credible. During 2000 to 2010,the sensitivity coefficient of the water,grassland and desert kept rising in each terrain area,whereas woodland and cultivated land kept declining. Based on the quantitative measurement of the terrain gradient effects of the ESV driven by land-use change,the spatial differentiation and its change of ESV with the change of terrain gradient were clarified. The results can provide the theoretical basis for protecting regional ecosystem and rational use of land resources in the future.