中文摘要：

林火是北方针叶林的一种主要干扰方式，不仅影响森林生态系统的生产力和物种多样性，还影响元素的生物地球化学循环。本文选择大兴安岭呼中自然保护区2010年火烧迹地为研究对象，并选择附近未火烧区作为对照样地，分析了火烧（火后1年）对土壤理化性质、土壤微生物生物量和有效养分（N、P、K）的影响。结果表明：与对照区相比，林火显著改变了兴安落叶松林土壤的理化性质，即土壤湿度、有机层厚度、溶解性有机碳、C：N均显著减小，而土壤pH值则显著上升；同时林火显著减少了土壤微生物生物量，但上述所有土壤性质指标在火烧强度处理间差异不显著。相较于对照样地，轻度火烧和高强度火烧后，土壤有效氮含量均显著增加，但火烧强度间差异不显著；火后土壤有效磷含量也显著高于对照区，且高低强度火烧间存在显著差异；而有效钾变化不显著。

英文摘要：

Fire is a major disturbance in boreal forest ecosystems, affecting not only forest pro ductivity and species diversity but also biogeochemical processes. In this study, we investigated the effects of fire （ one year after fire） on soil physicoehemical properties, microbial biomass and nutrients （N, P, and K） availability in a boreal Dahurian larch forest that was burned in year 2010 at the Huzhong Natural Reserve in the Great Xing＇ an Mountains of Northeast China. Our results showed that fire significantly decreased soil moisture, organic matter depth, dissolved or ganic carbon content, total C ： N ratio and microbial biomass in burned plots, but increased soil pH significantly, as compared with the control plots. However, no significant differences were observed in these soil properties between different fire intensities. After light and heavy fires, the soil N availability was significantly higher than the control, but less difference was found between the two fire intensities. Soil P availability was also significantly higher after fire, and there exis ted significant difference between the two fire intensities. Fire showed no significant effects on soil K availability.