Estimation Of Forest Soil Organic Carbon Content After Fire Disturbance In The Great Hinggan Mountains

Fire is a critical disturbance that alter dynamic changes of soil organic carbon?SOC?content of coniferous ecosystems in the Great Hinggan Mountains.Investigating potential influencing factors of SOC and its spatial distribution pattern can provide a scientific guidance for the climate change responding and international carbon emissions trading.Therefore,this study used field investigation,remote sensing,and statistical methods to explore:1)effects of fire severities and recovery time on organic carbon content of forest soil;2)the relative contributions of fire disturbance,vegetation and topography;3)spatial distribution patterns of post-fire SOC content in the Huzhong forest bureau on the north side of the Great Hinggan Mountains.This study concluded:?1?From the perspective of fire severity,the low-severity burning was beneficial to SOC increasing of the 0-20cm layer.The SOC of the 0-10cm and 10-20cm layers in forest-lands with low-severity burning was approximately 12.53g·kg^-1 and14.08g·kg^-11 higher than that in the unburned forest-lands,respectively.The SOC in0-20 cm layer can restore to pre-fire after high-severity burning.The SOC?20-30cm layer?in the moderate-severity burned forests was 7.56⁹.3g·kg^-1 higher than that in unburned,low-severity,and high-severity burned forests.?2?In terms of recovery time,the SOC in the 0-20cm was increased as increasing time after fire burning and finally reached the pre-fire level.The lowest SOC content was observed 3 years after fire burning,which was approximately 4.63²0g·kg^-1.High SOC content in recovery time is 10 years,compared with the unburned,the value was about 8.03¹6.59g·kg^-1.?3?From the perspective of combining effects of fire severity and recovery time,the SOC content in low and moderate severity was the highest in 10 years after fire.With the extension of the recovery time,the SOC content in all layers showed an rising trend and the range was 23.9%³4.26%.?4?For the topography factors,elevation and position had the largest contributions?the largest importance value was 18%?;for vegetation factors,canopy's contribution was highest?26%?;for fire factors,the contribution of fire severity accounted for a large proportion?about 17%?.Fire severity had a direct and important influence on the change of soil organic carbon content.In Huzhong Forest Bureau,there are many Pinus pumila in high altitude area.The trunk of Pinus pumila is usually recumbent with many branches at the base.It grows like a cluster when growing on the top of the mountain which has high litter fuel load,strong spatial continuity and high turpentine.Therefore,the high severity fire usually occur in this vegetation area.It also can explain the importance of elevation and fire severity partly.?5?Based on the formula established for quantifying relationships between SOC content and factors,we derived that the burned SOC content was significantly different from the unburned,especially the 0-10cm soil layer.The spatial pattern of SOC content was primarily affected by topography's variation,and then vegetation's variation in the study area.The results indicated that the combining effects of fire,topography and vegetation on SOC should be considered in post-fire forest soil carbon estimation in the Great Hinggan Mountains.