伊河流域景观格局变化及其驱动机制

Landscape pattern change and its driving mechanism in Yihe River basin,China

以伊河流域1987、2000、2008和2013年4期土地覆被数据、同期气象资料及社会经济数据为基础,综合运用景观生态学原理及Arc GIS 10.2、Fragstats 4.2和SPSS 17等工具,从不同时空尺度分析伊河流域景观格局变化及其驱动机制.结果表明:1987—2013年,研究区景观空间结构发生明显改变,伊河流域的林地、草地、库塘和建设用地面积增加,耕地、河渠面积呈现"减少-增加-减少"的趋势;1987—2008年,耕地主要转换为建设用地,2008—2013年,耕地、林地和草地之间的转移明显;景观空间格局的变化主要集中在海拔550 m以下的河谷平川和丘陵地带,山地景观格局随人类活动影响的加深也开始发生变化.景观格局指数分析表明:耕地与林地的最大斑块指数和聚集度指数最大;1987—2013年,伊河流域的斑块个数持续快速增长,分离度、Shannon均匀度指数和Shannon多样性指数呈"增大-略有减小-增大"的趋势,说明景观格局趋于不稳定,景观异质性增强.社会经济发展与人口增加是耕地、未利用地等景观类型向建设用地转化的主要驱动力;气温上升与蒸散发量增加是流域水域面积变化的直接原因;政策是流域林地、草地等景观结构发生变化的根本原因.

On the basis of land cover data in 1987, 2000, 2008 and 2013, meteorological data and the social-economic data in the same period of Yihe River basin, the landscape pattern change and its driving mechanism in this area were analyzed at different spatial-temporal scales by applying the theory of landscape ecology and using tools such as ArcGIS 10.2, Fragstats 4.2 and SPSS 17.0. Re- suits showed that between 1987 and 2013, the spatial structure of landscape in the study area was changed obviously. The areas of forest land, grassland, reservoirs and construction land increased, while the areas of cultivated land and canals had a trend of ＂decrease-increase-decrease＂. From 1987 to 2008, cultivated land was mainly transformed to construction land, and from 2008 to 2013, the transformation among cultivated land, forest land and grassland was significant. The variation of landscape spatial pattern was concentrated in the valley plains and hilly areas with elevations under 550 m. But as the disturbance of human activities were much stronger, landscape patterns in moun- tain areas began to change. The analysis of landscape pattern index showed that cultivated land and forest land had the greatest largest patch index （LPI） and cohesion index （COHESION）. Between 1987 and 2013, the number of patches （NP） in Yihe River basin increased rapidly. The landscape division index （DIVISION）, Shannon＇ s evenness index （SHEI） and Shannon＇ s diversity index （SHDI） all showed the trend of ＂increase-slight decrease-increase＂, which indicated that the land- scape pattern tended to be unstable, and landscape heterogeneity increased. Social-economic devel- opment and the population growth were main driving factors of the transformation of cultivated land and unused land into construction land. The rising temperature and evapotranspiration directly caused the change of water area in this river basin, and the policy was the fundamental reason for the changes in the structures of forest land and grassland.