北京郊区土地利用变化及其生态效应研究

Land Use Change and Its Ecological Effects in the Suburbs of Beijing City

以京郊3个具有不同功能的区(县)为例,利用从1996年、2005年TM影像中获取的土地利用数据,在分析研究区近10年的土地利用变化的基础上,通过构建生态价值指数(EVI)和土地利用变化的生态价值转移率(TREV),从土地利用变化所引起的各类型间生态价值转移的方向、幅度等方面对北京郊区土地利用变化的生态效应进行定量研究。结果表明:1996—2005年研究区的林地、草地、建设用地增加,而耕地、水域和未利用地减少,各土地利用类型的变化速度依次为建设用地>水域>耕地>草地>林地>未利用地;从区域看,土地利用相对变化速率从快到慢依次是城市功能拓展区(朝阳区)、城市发展新区(顺义区)、生态涵养发展区(密云县);从类型变化看,以耕地、水域的转出和建设用地的转入为主。研究时段内研究区的生态价值指数总体呈下降的趋势,各区县的区域生态价值指数差异较大,且相对差异还在扩大,其指数下降速度从快到慢依次是朝阳区、顺义区、密云县;同时从分布变化看,EVI中值波动区减少,EVI较低区和EVI低值区增加,导致了研究区总生态价值指数有所下降。

Using the data of land-use change produced from the integrating Landsat TM images of Beijing City in 1996 and 2005,we quantified the characteristics of LUCC and its ecological effects through developing regional ecological value index and transfer rate of the ecological value.The results showed that,from 1996 to 2005,the area of forestland,grassland,construction land increased while the area of cropland,water body and unused land decreased.The speed of individual land use change is in the order：construction land〉watercropland〉grassland〉forest〉unused land.The order of land use relative change rate from big to small value is the Chaoyang District,Shunyi District,Miyun County.With the speedup of the economic development and the urbanization,the transition among the land use types in suburbs of Beijing became dramatic,among which the transition from cropland,water body to other types and from other types to construction land are the most important land use change.From 1996 to 2005,the ecological value index（EVI）in suburbs of Beijing City showed the downward trend,the improvement and degradation of ecological environment coexisted.The change of cropland,water body and construction land affected ecological environment negatively,while the increase of forestland and grassland improved the ecological environment and its ecological value index.The disparity of the regional ecological value index is still expanding in suburbs of Beijing City and the order of the regional ecological value index from big to small value is the Chaoyang District,Shunyi District,Miyun County.The area of high-EVI land decreased and the area of low-EVI land increased,which resulted in the downward trend of EVI in the study area.