环境科学
土壤水分
有机质
生态系统
土壤有机质
土壤碳
植物凋落物
森林地面
总有机碳
垃圾箱
碳循环
规定烧伤
农学
环境化学
土壤科学
生态学
化学
生物
作者
Adam F. A. Pellegrini,Anthony C. Caprio,Katerina Georgiou,Colin Finnegan,Sarah E. Hobbie,J. A. Hatten,Robert B. Jackson
摘要
Abstract The impact of shifting disturbance regimes on soil carbon (C) storage is a key uncertainty in global change research. Wildfires in coniferous forests are becoming more frequent in many regions, potentially causing large C emissions. Repeated low‐intensity prescribed fires can mitigate wildfire severity, but repeated combustion may decrease soil C unless compensatory responses stabilize soil organic matter. Here, we tested how 30 years of decadal prescribed burning affected C and nitrogen (N) in plants, detritus, and soils in coniferous forests in the Sierra Nevada mountains, USA. Tree basal area and litter stocks were resilient to fire, but fire reduced forest floor C by 77% (−36.4 Mg C/ha). In mineral soils, fire reduced C that was free from minerals by 41% (−4.4 Mg C/ha) but not C associated with minerals, and only in depths ≤ 5 cm. Fire also transformed the properties of remaining mineral soil organic matter by increasing the proportion of C in a pyrogenic form (from 3.2% to 7.5%) and associated with minerals (from 46% to 58%), suggesting the remaining soil C is more resistant to decomposition. Laboratory assays illustrated that fire reduced microbial CO 2 respiration rates by 55% and the activity of eight extracellular enzymes that degrade cellulosic and aromatic compounds by 40–66%. Lower decomposition was correlated with lower inorganic N (−49%), especially ammonium, suggesting N availability is coupled with decomposition. The relative increase in forms of soil organic matter that are resistant to decay or stabilized onto mineral surfaces, and the associated decline in decomposition suggest that low‐intensity fires may promote mineral soil C storage in pools with long mean residence times in coniferous forests.
科研通智能强力驱动
Strongly Powered by AbleSci AI