不同强度火烧对轻组和重组有机碳的影响

Effects of Different Fire Intensities on LFOC and HFOC

[目的]研究火烧迹地中土壤轻组有机碳和重组有机碳含量及其与相关因子的关系。[方法]通过野外采样和室内分析，研究了大兴安岭地区不同强度火烧迹地0～15cm土壤轻组有机碳和重组有机碳含量的差异及其与相关因子的关系。[结果]对照样地、低强度和高强度火烧样地中轻组有机碳含量分别为2．53～10．15g／kg、3．06～12．37g/kg和2．16～11．66g/kg，轻组有机碳占总有机碳的比例为5．69％～19．60％，均值表现为低强度火烧轻组有机碳含量〉高强度火烧轻组有机碳含量〉对照样地轻组有机碳含量，差异不显著（P〉0．05），但轻组有机碳含量在不同月份差异显著度不同；不同强度火烧样地中重组有机碳含量分别为35．09～54．59g/kg、35．83～64．15g／kg和23．83～51．11g／kg，重组有机碳占总有机碳比例为80．40％～94．31％，均值表现为低强度火烧重组有机碳含量〉对照样地重组有机碳含量〉高强度火烧重组有机碳含量，差异显著（P〈0．05）。[结论]对照样地、低强度和高强度火烧样地中轻组有机碳均值大小依次为低强度、高强度、对照样地，重组有机碳均值大小依次为低强度、对照样地、高强度。土壤轻组有机碳和重组有机碳含量与全氮呈正相关，与土壤温度、含水率呈负线性相关。

[ Objective ] Studying the contents of light fraction organic carbon（LFOC） and heavy fraction organic carbon （HFOC） in the burned areas is an important method to reveal fire disturbance of soil organic carbon cycle. [ Method] Through field sampling and lab analysis, we studied the content differences and correlations of LFOC and HFOC in 0 - 15 cm deep soil in the Daxinganling Mountain areas that were burned under different fire intensities. [ Result ] The results showed that the contents of LFOC in unburned, low intensity and high intensity sample were 2.53 - 10.15 g/kg, 3.06 - 12.37 g/kg and 2.16 - 11.66 g/kg. That light fraction organic carbon accounts for the proportion of the total organic carbon was 5.69% - 19.60%. The results showed that LFOC in high-intense burned sample areas was greater than that in unburned areas, but LFOC in low-intense burned sample areas was greatest. However, the differences were not significant （P 〉 0.05 ）. The contents of heavy fraction organic carbon in unburned, low intensity and high intensity sample were 35.09 - 54.59 g/kg, 35.83 - 64. 15 g/kg and 23.83-51.11 g/kg. That heavy fraction organic carbon accounts for the proportion of the total organic carbon was 80.40% -94.31%, HFOC in low-intense burned sample areas was greater than that in unburned and high-intense burned sample areas, and the HFOC in un- burned sample areas was greater than high-intense burned sample areas, the differences were significant （ P 〈 0.05 ）. [ Conclusion ] The LFOC from high to low in order was low-intense burned sample, high intensity sample, unburned sample. The HFOC from high to low in order was low intensity sample, unburned sample, high intensity sample. The LFOC and HFOC were positively linear correlated with total nitrogen, and were negatively linear correlation with soil temperature and moisture content.