关键词: 杉木, 连栽障碍, 土壤微生物, PCR-DGGE, 生物多样性

Abstract: Based on the multiple-temporal MODIS EVI data in 2007, and by using d ecision tree classifier, the ecosystems in Haihe River Basin were classified, an d their spatial pattern as well as its relationship to topography was analyzed. The classification based on the MODIS EVI data had an overall accuracy of 856% and a Kappa coefficient of 082. Different ecosystems distributed at different elevations. Cropland, urban, and wetland ecosystems mainly distributed on the p lains below 200 m, occupying 538%, 10%, and 13% of the total area, respect ively, forest ecosystem mainly located on the low mountains between 500 m and 10 00 m, accounting for 225%, while grassland ecosystem mainly distributed at the elevations above 1000 m, accounting for 214%. Different ecosystems showed dif ferent distribution trend to slope. Cropland, urban, and wetland ecosystems main ly distributed on the slopes <2°, while forest and grassland ecosystems were ma inly on the slopes between 5° and 15°. With increasing slope, the percentages of cropland, wetland, and urban ecosystems decreased, that of forest ecosystem i ncreased, while grassland ecosystem had a decreased percentage after an increasi ng to a peak.

Key words: Chinese fir, Continuous planting, Soil microbes, PCR-DGGE, Biodiversity