关键词: 土壤微生物, 提取与纯化

Abstract: Urbanization is a massive and unplanned experiment that already affects large acreages worldwide,and has profound social and ecological consequences for both urban and rural residents.Therefore,to comprehensively quantify the urbanization process and to investigate its ecological consequences become the central issues in urban ecological studies.Combining urbanization expanding index with landscape metrics,this paper quantified the urbanization expanding process and the urbanization spatial characteristics in Changping District of Beijing.The results showed that there were three main urbanization models,i.e.,urban fringe belt?expending model,main transportation routes line-expending model,and satellite city panel-expending model.The urbanization expansion index showed that urbanization mainly took place during the period from 1989 to 1996,and the urban landscape metrics indicated that there were urban patches isolated expanding and new urban patches emerged from 1989 to 1996,mainly amalgamated expanding from 1996 to 2001 in urban fringe belt?expanding region.In transportation routes line-expanding region,the urban patches isolated expanding,amalgamated expanding and new urban patches emerging took place simultaneously,and mainly urban patches amalgamated expanding during the former period,and new urban patches constantly turning up around satellite city during the latter in satellite city panel-expanding region.This study showed that urbanization expansion integrating landscape metrics might reveal the urbanization expanding process and its spatial characteristics,and would be a good example for the application of landscape metrics.

Key words: Soil microorganism, Extraction and purification