关键词: 松辽平原&ldquo, 玉米带&rdquo, 农田景观结构, 多样化程度, 动态分析

Abstract: The Songliao Plain in Northeast China is one of the nation’s most important bases of grain production. Its corn production accounts for one third of the national total production. More than half of the nation’s corn export comes from the region. The natural conditions of the region are similar to those in other corn producing areas of the world. To provide a realistic basis for the allocation of farmland for using 40 years of data, this paper examines the structure and char-acteristics of farmland in the Songliao Plain, focusing on the changing ratio and diversity index of farmland use. In the paper, first, the farmland landscape structure and feature of the Songliao Plain "corn belt" are analsysed from the three aspects梒rop habitats, crop ecotypes and crop species. Then, according to the statistics data computting the rate and diversity index of the farmland landscape factors and drawing out the diversity index curve of the dynamic changes,From these the 40 years’ dynamic changes of the farmland landscape in the area are showed. It is hoped only that the result can provide some reference materials for the reasonal match and steady development of the farmland landscape ecosystem.The main points are as follows :The farmland is the major landscape in Songliao Plain "corn belt", so the reasonal match of the farmland structure are important to assure the stable development of the landscape ecosys-tem and steady grain productive process.Because the farmland is a landscape category which was formed by human agro-action, there the feature of the artifical landscape is quite clear, There are limited species of crops in which the corn is absolute predominance and becomes more and more,so that the structure of landscape becomes simple day by day. In order to keep the production of grain the material-e-merge flow throuagh the farmland are artifical increased, so the self-regulate ability of the land-scape become to decrease. The farmland landscape system is more unstable and changeable.The landscape diversity is the expression of the complex and disparty of the landscape structure,The change of the landscape diversity shows the change trend of the ladnscape. In the area, qn the one hand, since 1949 the change of the farmland structure is showed the increaseing trend on the aspect of the crop habitats’ diversity, and on the other hand the changes of farm-land structure are showed the decreasing trend of the crop ecotypes and crop species dicersity af-ter mid of 70’s when the "corn belt" was fromed.

Key words: Songliao Plain "Corn-belt ", farmland stucture, diversity, dynamic change