退耕还林还草政策影响下米脂县银州镇土地利用变化研究

以米脂县银州镇1986年和2006年两期TM影像及1996年土地利用现状图为基础,结合GIS空间分析软件和遥感软件,分析了1986-1996年、1996-2006年以及1986-2006年的土地利用时空变化.研究表明,1986-1996年期间,土地利用变化表现为水域、林地和草地减少,耕地和其它用地增加,其中尤以耕地面积变化最为显著,减少的林地和草地主要转化为耕地;1996-2006年期间,主要的土地利用变化表现为水域、耕地和其它用地减少,林地和草地增加.由于受到退耕还林还草政策的影响,耕地减少主要表现为转化成林地和草地.总体上看,1986-2006年期间,银州镇土地利用变化显著,主要表现为水域、林地和耕地面积减少,草地和其它用地面积增加,水域、林地和耕地主要转化为草地.1986-2006年土地利用变化主要发生在粱峁地上,有部分无定河两岸的水浇地转化为其它用地.退耕还林还草工程在改善当地生态环境方面虽取得了一定效果,但生态环境的保护和恢复仍是一个长期的任务.

Land Use Change Affected by Policy of Returning Farmland to Forest and Grassland in Yinzhou Town, Mizhi County

Taking two composite Landsat 5 TM (thematic mapper) images in 1986 and 2006 and land use map of Yinzhou town, Mizhi County in 1996 as data resources, land use/land cover changes (LUCC) of Yinzhou from 1986 to 2006 are studied using the Geograp hical Information System(ArcGIS 9.0) and ERDAS( remotesensing software). Results show that great changes have taken place in land use/ land cover in Yinzhou from 1986 to 2006. From 1986 to 1996, change of land use structure was characterized by increases in cropland and other land use types and on the contrary water area, by decreases in woodland and grassland. Cropland changed obviously and woodland and grassland were mainly converted into cropland. From 1996 to 2006, change of land use structure was characterized by increases in woodland and grassland increased. On the contrary, water area, cropland, and other land use types decreased. Cropland was mainly converted into woodland and grassland driven by the policy of returning farmland to forest and grassland. From 1986 to 2006, change of land use structure was characterized by increases in grassland and other land use types increase and on the contrary, by decreases in water area, cropland, and woodland. Water area, cropland, and woodland were mainly converted into grassland and other land use types. Land use change was mainly taken place in slope area and some croplands beside Wuding River were converted into other land use types. Although the ecological environment had been greatly improved in the area, it is still a long term task to protect and recover ecological environment by the policy of returning farmland to forest and grassland.