近50年来霍林河流域下游沿岸土地利用变化过程

本文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,通过分析不同时段各土地利用类型的动态变化及其转换过程,揭示近50年来霍林河流域下游沿岸土地利用变化过程及其规律。研究得出,耕地和草地是霍林河流域下游沿岸的主要土地利用类型,次之为盐碱地,湿地和林地比重较小,人居地和沙裸地最小。计算土地利用动态度进行土地利用变化的数量分析发现,各土地利用类型之间以及同一土地利用类型在不同的研究时段都呈现出显著差异的速度变化,表现在速度变化的绝对量上、速度变化的方向上和土地利用综合动态度上,耕地和草地始终相反的速度变化方向说明二者之间存在密切的相互转换关系,而人居地和盐碱地始终一致的速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。土地利用转换分析显示,霍林河流域下游沿岸各土地利用类型稳定性排序为耕地>湿地>人居地>盐碱地>林地>草地>沙裸地,它们之间的转换变化具有显著的差异性,同一土地利用类型在转出和转入土地利用类型及其转换量上的表现不同,且随时间推移亦发生变化,且这种转换变化在区域分布及空间构型上存在差异。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类型的动态变化。

Land- Use Changes Along the Lower Reaches of Huolin River in the Last 50 Years

Huolin River is in arid and semi-arid regions of China,the land-use spatial data of which was built on the basis of topographic maps of 1954 and 1964,and remote sensing data of 1986,1996 and 2000.By analysing 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 farmland and grassland,followed by salinized land took the leading place,the proportions of wetland,woodland,residential land and sand land were relatively low.By calculating the land-use dynamic degree,the quantity variation of land use was analyzed.Remarkable speed variation differences were detected in various land use types,as well as in different research intervals of an identical land use type,that was embodied by the absolute magnitude and direction of speed variations and the compositive dynamic degree of land use.All the time,the farmland and grassland were changing in opposite directions,which indicated close inter-conversion relationship between them,while the residential land and salinized land varied in same directions all the way,from which we could conclude that human disturbance activity was the main factor for the expanding of salinized land.Land-use transition analysis manifested that the stability of various land-use type was ranked with the farmland in the first place,followed by wetland,residential land,salinized land,woodland,grassland and sandy land in order.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.Besides,this transition changes diversified greatly in aerial distribution and spatial configuration.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.