火烧强度和火后恢复时间对大兴安岭森林土壤有机碳含量的影响

在大兴安岭针叶林生态系统中,林火是驱动森林结构与功能变化的主要因子之一,对土壤碳循环过程产生了深刻影响.本研究在大兴安岭林区选择不同火烧强度(轻度、中度、重度)和火烧年份(1987-2012年)的火烧迹地开展野外调查,分土壤发生层(O层、A层、AB层、BC层、C层)采集样品,采用双因素方差分析和多重比较法,分析了火烧强度和火后恢复时间对森林土壤有机碳含量的影响.结果表明: 中度和重度火烧后,土壤O层有机碳含量呈逐年上升趋势;A、B层土壤有机碳含量在轻、中度火烧后呈逐年下降趋势,其随时间的变化情况为火后3年>火后5年>火后10年>火后10年以上,在重度火烧后的10年之内呈逐年上升趋势,但在火后10年以上又迅速下降;BC层有机碳含量变化无明显规律.

Effects of fire severity and recovery time on organic carbon content of forest soil in Great Xing’an Mountains,China.

Fire is one of the major factors that alter structure and function of forest in the Great Xing’an Mountains, with consequences on soil carbon cycling in forests. In this study, we collected soil samples (layers O, A, AB, BC, and C) under different fire-severity levels (low, moderate, and high) and post-fire recovery times (1987-2012) in the forests of Great Xing’an Mountains. Analysis of variance and multiple comparison were used to analyze effects of fire severity and reco-very time on content of soil organic carbon. The results showed that soil organic carbon (SOC) content in layer O presented a rising trend under both moderate- and high-severity fire disturbances. The content of SOC in layers A and B decreased year by year under low- and moderate-severity fires, which ranked in the order: 3 years > 5 years > 10 years > over 10 years since fire. The content of SOC under high-severity fire presented an increasing trend within 10 years since fire distur-bance and then decreased rapidly over 10 years. The content of SOC in layer BC presented no obvious changes.