火烧对北亚热带天然次生林土壤有机碳的影响

【目的】研究火烧对北亚热带天然次生林土壤有机碳的影响,为火后森林生态系统恢复提供参考。【方法】以北亚热带天然次生林火烧迹地为研究对象,灾后1 a在火烧迹地和对照林地上分别设置20 m×20 m样地各5块,分层采集0~50 cm土层的土壤样品,测定各层土壤有机碳和土壤养分含量。【结果】火烧迹地土壤里含有的轻组有机质、易氧化碳、有机碳均比对照区域高,上升的幅度分别为1.2%~61.5%、9.6%~47.4%、3.9%~35.1%,且在0~10 cm土层的差异极显著(P0.01)。次生林火灾之后,轻组有机质、易氧化碳、总有机碳基本都存储于土壤表层,深度为0~20 cm。火烧迹地土壤0~50 cm的剖面中,含有的有机碳比对照区域高,上升的幅度约18.8%且差异显著。过火后土壤总有机碳、易氧化碳和轻组有机质与土壤养分(全氮、水解氮、速效钾)的相关性均达到极显著水平。【结论】天然次生林发生火灾1 a后,火烧迹地土壤总有机碳、土壤养分的增加主要集中在表层土壤中。

Effects of fire on soil organic carbon in natural secondary forest in north subtropical areas

Objective]This study was aimed at examining the effects of fire on soil organic carbon in a natural secondary forest in north subtropical regions of China.Method] Experiments were conducted to analyze changes in soil organic car-bon and soil nutrient levels at a depth of 0-50 cm in one year after a fire in anatural secondary forest located in the north subtropical regions. Five sample plots were established in the burnt forest regions and control regions which size of 20 m× 20 m, soil samples from 0-50 cm deep layers were collected, and the levels of soil organic carbon and soil nutrients were measured.Result] Light fraction organic matter(LFOM), easily oxidized carbon(EOC) and soil total organic car-bon(TOC) levels were higher in the burnt forest soil than the control area, which increased by 1.2%-61.5%, 9.6%-47.4%, 3.9%-35.1%, respectively. The changes in these indicators reached significance at soil depth of 0-10 cm (P<0.01), implying that after the increase in TOC, soil LFOM and EOC were basically on the surface, and carbon in soil storage at a depth of 0-50 cm increased by 18.8% in one year after the forest fire compared with the control areas. LFOM, TOC and EOC directly affected the nutrient status of the soil, especially after the forest fire. Conclusion] In one year after the forest fire, TOC and soil nutrient content increased mainly in surface soil.