黄土高塬沟壑区小流域土地利用变化及其生态效应分析

基于王东沟流域1994和2004年两期土地利用图，通过构建土地利用动态变化模型和区域生态环境指标，定量分析了王东沟流域1994--2004年土地利用时空变化特征，并以生态系统服务功能衡量了土地利用类型和土地利用变化类型的生态效应．结果表明，1994—2004年王东沟流域农地大幅度减少，草地和果园大量增加，林地和非生产地变化不大；变化速度依次为草地〉果园〉非生产地〉农地〉林地；土地利用变化类型多样，农地转出和林地转入是其主要类型；土地利用的空间迁移方向为农地和果园向西北方向迁移（塬区），林地和草地向东南方向（沟壑区）迁移．1994--2004年土地利用变化带来了良好的生态效益，但不同土地类型和不同土地变化类型的生态效应不同，提高和降低生态系统服务功能的作用并存．农地减少对生态环境产生负面作用，林草和果园的增加改善了生态环境，提高了其生态服务价值；土地利用变化类型中，改善生态环境的主要是转为林地和果园的变化类型，降低生态系统服务功能的主要是林地转出类型和农地转为非生产地类型．

Land use/land cover change and their ecological effect in small watershed on gully region of the Loess Plateau

Based on land use data of 1994 and 2004 in Wangdonggou watershed, through developing dynamic model of LUCC and indices of regional ecological environment, this paper quantified the characteristics of LUCC and its ecological effect. The results showed that from 1994 to 2004, farmland decreased while grassland and orchard increased greatly, forest and nonproductive land changed little. The speed of individual land use changes was in the order of grassland>orchard>nonproductive land>farmland>forest land. As to the spatial change, a total of 11 major land use change types were identified, among which the change from farmland to others and form others to forest were the most important land use change. The gravitational center of farmland and orchard moved to the northwest tableland, while those of forest land and grassland moved to the southeast gully land. From 1994 to 2004, owing to LUCC, the ecological environment was improved, but the type of land use and their change took effect differently with both improving and decreasing effect. The decrease of farmland affected ecological environment negatively, while the increase of forest and grassland and orchard improved the ecological environment and its ecosystem service values. Those improving the ecological environment were from other types of land use to forest and orchard, while those worsening the ecological environment were from forest to others and from farmland to nonproductive land.