关键词: 禽流感病毒, 禽流感病毒, H9N2 亚型, M基因, 进化分析, 致病性

Abstract:

In order to quantify the spatial variability of land use structure in Handan, from landscape and ecological points of view, the author expounded spatial structure characteristics of land use of Handan, and a series of indexes, such as Gibbs-Martin diversity index, land use intensity index, biological abundance index and vegetation cover index were applied to analyze the spatial structure characteristics of land use for the year 2006. These indexes were all gridded with 1 km×1 km cells to detect spatial heterogeneity. The results showed that land use category of Handan was complete in 2006. The land use, cover diversity index and the land use extent index turned out to be gradually decreasing from the middle regions and east-south regions to the round region in radial trend. The land use structure showed that: the woodland almost gathered in the west mountain area, the cultivated field mainly be distributed in east-south area in ring station, the urban land mainly be scattered in middle region in caky station, the country land unorganized around the town; the study also found that the change trend of biological abundance index was same as the change trend of vegetation cover index, they both showed the degressive trend from center region to fringe region.Handan was complete in 2006. The land use, cover diversity index and the land use extent index urned out to be gradually decreasing from the middle regions and East-South regions to the round region in radial trend. The land use structure shows that: the woodland almost gather in the west mountain area, the cultivated field mainly be distributed in east-south area in ring station, the Urban Land mainly be scattered in middle region in caky station, the country land unorganized around the town; the study also find that the change trend of Biological abundance index is same as the change trend of Vegetation cover index, they both show the degressive trend from center region to fringe region.