Analysis on land use trend in some typical regions in the Ordos Plateau.

Land use/cover change(LUCC) is a key field in the globe change research.Thus,many researches on LUCC have been carried out in recent years.Farming-pasturing ecotone is a special ecological-fragile zone in China,especially in north China.The Ordos Plateau is located in a farming-pasturing ecotone in north China,so the research on LUCC is of significance in revealing the information of environment change.In this paper,the land use maps in 1985,1995,2000 and 2004 are interpreted from Landsat TM images and used to analyze the dynamics in some typical regions in the Ordos Plateau.The results show that the LUCC in the regions was obvious during these periods.Firstly,the only landscape matrix in the study area is grasslands with a vegetation coverage range of 69.29%～82.25%.Secondly,the stability of different land use types is different.The most stable types are grasslands and unused land,their stability is higher than 87%.The changing directions of land use types are as follows: the first one is the change from cropland,unused land and woodlands to grasslands,the second one is that from grasslands to waters and construction land,and the third one is that from construction land to unused land.In order to discuss the spatial and temporal stability of the different LUCC types,the transition probability method is used in this study.If 50% of a LUCC type can be maintained stable in spatiality at different time stages,it is considered that this LUCC type has a high stability.From this viewpoint,it is found that the stability of grasslands is the highest,and then that of unused land and construction land.Thirdly,the reduction of cropland and unused land with the increase of woodlands and grasslands reveals that the environment in the Ordos Plateau has been improved.