STUDY OF LAND USE CHANGE IN YULIN PREFECTURE

This paper takes Yulin prefecture as an example. Yulin prefecture is located in the Northern-most part of Shaanxi province ,between 36°ã57°äand 39°ã34°äN and 107°ã28°ä and 111°ã15°ä; It covers an area of 43578km2, accounting for 22% of the total Shaanxi province. Climate type is temperate and temperate semi-arid continental monsoon climate. Mean annual air temperature is about 10°æ. Mean annual precipitation is 400mm, with most of the rainfall occurring in July and August, only little falls between November and January and has large annual and seasonal amplitudes. In spatial the rainfall decreases from Southeast toward Northwest. Located in the transitional zone from agricultural to husbandry areas. Yulin prefecture not only has its special spatial pattern in physical geography, but also has typical characteristics of fragile ecosystem and differentiation rule in ecology. Located in transition area of Loess Plateau and Mu Us desert, Yulin prefecture has the problem of serious soil erosion and water shortage. It is selected as a typical area for the ecosystem assessment of western China project. Depending on 1986 and 2000 TM images and other data, we achieved the land-use change data after interpretation. This paper analyzed the situation of land-use change in temporal and spatial aspects with the GIS and statistic methods. Then this paper analyzed the situation of landscape change with FRAGSTATS 3.3,the most famous landscape structure analysis program. Various landscape metrics are calculated at class and landscape levels. The results show that: in recent 14 years the un-used land decreased by 1305.56 km2, cultivated land increased by 567.11 km2, forest land and grassland increased by 99.6km2 and 616.79km2 respectively. The change rate of un-used and construction land is most high. There is obvious area differentiation in land-use change. In the direction of land-use change the conversion from un-used land to grassland and from grassland to forest and cultivated land is prominent. The results also show that the landscape structure changed dramatically during the past 15 years. The land conservation works well in recent years.