霍林河流域下游沿岸近50年土地利用/覆被变化研究

Land Use/Cover Changes along Lower Reaches of Huolin River in Last 50 Years

以干旱半干旱脆弱区霍林河流域下游沿岸为研究靶区,利用1954年和1964年地形图,1986,1996和2000年的TM遥感影像作为基本信息源,在GIS支持下,建立土地利用空间数据库。引用空间测算模型和累计转换概率,分析不同时段各土地利用/覆被类型的动态和转换变化,揭示霍林河流域下游沿岸近50年土地利用/覆被变化过程及规律。耕地和草地是霍林河流域下游沿岸的主要土地利用/覆被类型,次之为盐碱地,湿地和林地比例较小,居民地和沙裸地最小。耕地和草地始终相反的幅度变化方向说明二者密切的相互转换关系;人居地和盐碱地始终一致的幅度变化方向则说明人类干扰活动是研究区盐碱地面积扩张变化的一个主要因素;沙裸地最快的转移速度预示着研究区沙化状况有较大的改善空间;耕地最慢的转移速度体现出其作为研究区基质的功能;草地较高的转移速度使其丧失了研究区第二大土地利用覆被类型的地位。霍林河流域下游沿岸各土地利用/覆被类型之间的转换变化具有显著的差异性,同一土地利用/覆被类型在转出和转入土地利用/覆被类型及其转换量上的表现不同,且随时间推移亦发生变化,转出的减少作用和转入的增加作用相叠加决定着研究区不同时段各土地利用/覆被类型的动态变化。

Taking the lower reaches of Huolin River, which is in arid and semi-arid regions of China, as study area, the land-use spatial data was built on the basis of topographic maps in year of 1954 and 1964, and remote sensing data of 1986, 1996 and 2000. With the spatial analysis model and cumulative transition probability being introduced in the analysis of land use dynamic changes and transition procession during study periods, the land use variations along the lower reaches of Huolin river in the last 50 yeas were discussed. Results showed that the infield and grassland, followed by salinized land took the leading place, the proportion of wetland, woodland, residential land and sand land was relatively low. All the time, the infield and grassland were changing in opposite directions, which indicated close inter-conversion relationship between them two, while the residential land and salinized land varied in opposite directions all the way, from which we could conclude that human disturbance activity was the main factor for the expanding of salinized land. The fastest transition speed of sand land indicated that there was a relatively larger space for amending the sandy condition. The substrate function of infield could be seen from its lowest transition speed. The area of grass land dropped from the order of second to third for its relatively fast transition speed. The transition changes among different land-use types varied significantly. As to lands of identical use type, the types of transition inputs and outputs, as well as the transition magnitude, showed obvious differences and had tendency to varying with time. The dynamic changes of various land-use types in different intervals were controlled by the reduce function of transition outputs overlaying with the increase function of transition inputs.