Daan City's Agricultural Landscape Pattern Change Research

Landscape in the scale of a county is a complex ecological system of nature-society-economy, with the value of economical, ecological and cultural. The ecological managements in the county pay attention to only economical value and ignore the ecological value in a county. There are a serious of problems during the development of county, such as the confusion in the plan, the deterioration of ecological environment, the reduction of biodiversity. The main phenomena are the changes in the agricultural landscape pattern, and this changes can lead to the changes in the culture and function of landscape. The healthy and safety landscape pattern can not only exert the productive potent, but also conform to the structural rule of ecology environmental development in natural, and the environment will be ordinal and healthy, which is the target of landscape construct.Taken Da'an city in the west of Jilin Province as a case, this article studies the landscape pattern of a county in the edge of arg-herd in the past 20 years. By use the Remote Sensing(RS) and Geographical Information System(GIS), the author extracts the landscape pattern information in agricultural county, and analyses the characters of agricultural landscape pattern. In the end the author gains the character and trendy of landscape ecological pattern in northern edge, and indicate the ecological problem exiting in the agricultural development, which is the guide of management of agricultural ecological system and the making of ecological system policy. There are four parts in this article:First, this paper narrates briefly the general situation of area researched, including its position, range, natural condition and society-economy situation.Second, the base of theory and methods mainly introduce both the research principle for landscape structure and trends, and that for landscape classification, which mostly applies landforms and landcover second grade index.Third, This content is the main part of this paper. Above all, the characters of Da'an city's agricultural landscape pattern and each type distributing in middle 80s ,are indicated by analyzing its agricultural landscape pattern in this period. Whereafter, the one in 2000 is analyzed. Lastly, the changing character of Da'an city's agricultural landscapepattern is analyzed, pointing out its trends and character in the past 20years.Finally: the conclusion of this article.