近20年渔子溪流域土地利用变化的环境影响

采用渔子溪流域1986、1994及2002年的遥感影像资料,对流域土地利用变化导致的生态系统服务价值及景观格局指数的变化进行了定量分析.结果表明,在1986～2002年间,流域土地利用变化导致其总体生态系统服务功能增加了0.42%,其中产品供给功能、生态调节功能、生命系统支持功能、文化娱乐功能的相对变化率分别为1.15%、0.36%、0.16%和-0.94%,它们对总体生态系统服务功能变化的贡献率分别为62.95%、46.82%、6.33%和-16.1%.从景观格局变化来看,渔子溪流域的斑块密度指数在1986-2002年间从0.0016减小到0.0013,而景观破碎度指数从0.00307增大到0.00474,表明渔子溪流域的景观粒度减小而景观破碎化的程度提高.研究结果还表明,流域不同土地利用类型景观破碎度的变化趋势并不一致,其中耕地、疏林地、高覆盖度草地、低覆盖度草地和居民建设用地的破碎度指数有所增加,而有林地、灌木林、中覆盖度草地和永久性冰雪覆盖的破碎度指数有所下降,这主要是由于一些零散分布的灌木林被开垦为耕地或转变为居民建设用地及气候变暖使得部分永久性冰雪覆盖转变为中覆盖度草地等原因造成的.

Environmental impact of the land use change in Yuzixi Catchment in the last 20 years

Non-pollution ecological impact is an important aspect of the environmental impact resulting from land use change, which can be assessed by the change in the value of ecosystem services and landscape pattern index. The ecosystem service function and landscape pattern index of Yuzixi catchment are quantitatively analyzed based on the remote sensing images in 1986, 1994 and 2002. The results show that the ecosystem service value in Yuzixi catchment increased 0.42% from 1986 to 2002. Thereinto, the relative change rate of provisioning services, regulating services, cultural services and supporting services are 1.15% , 0.36% , 0.16% and -0.94% , respectively. Their contributions to the overall change of these ecosystem services are 62.95% ,46.82% ,6.33% and - 16.1% , respectively. On the other hand, the landscape pattern has been changed because of the land use change. The patch density index decreased from 0. 0016 to 0. 0013 and the landscape fragment index increased from 0. 00307 to 0. 00474. The results of further analysis show that the changes of landscape pattern of different land use types are different since some scattered shrub land has been transferred to cultivated land or village construction and some perpetual ice land has been transferred to moderate grass land due to climate change.