重度火烧对大兴安岭落叶松天然林土壤团聚体有机碳和黑碳的影响

为了揭示重度火烧对大兴安岭落叶松天然林土壤团聚体有机碳(SOC)和黑碳(BC)的影响,本文选取大兴安岭落叶松天然林重度火烧迹地为研究对象,并以未火烧落叶松天然林为对照,进行相关研究。结果表明:1)重度火烧明显增加表层土壤有机碳和黑碳含量。和对照样地相比,重度火烧迹地0~5 cm层全土有机碳增加了41.56%,黑碳增加了123.69%,黑碳含量增加显著(P0.05)。2)重度火烧明显增加了0~5 cm层的5 mm和0.25 mm团聚体比例,降低了0.25~5 mm团聚体比例。3)对照样地相比,重度火烧显著提高了0~5 cm土层内的5 mm和0.053 mm团聚体有机碳含量(P0.05),增幅达177.6%和127.27%。而0.25~2 mm团聚体有机碳含量在3个土层内较对照均有不同程度的降低。2种林地类型各粒径团聚体有机碳含量表现为随粒径增大而增加,随土层深度的增加而降低的趋势。4)团聚体中黑碳含量的分布规律与有机碳相似。重度火烧迹地0~5 cm层的5 mm、2~5 mm、0.053~0.25 mm、0.053 mm团聚体黑碳含量分别增加了4.92、4.19、1.06、0.44 g/kg,与对照之间的差异均达显著水平(P0.05);5)2种林地土壤团聚体BC/SOC比值在0.05~0.41之间,且重度火烧显著增加了BC/SOC比值(P0.05)。相关分析表明,各粒径团聚体有机碳和黑碳含量显著线性相关。 

Impact of severe burning on organic carbon and black carbon in soil aggregates in natural Larix gmelinii forest of Great Xing'an Mountains

The objective of this study was to reveal the changes of organic carbon (SOC) and black carbon (BC) in soil aggregates after severe burning. With unburned natural Larix gmelinii forest as contrast, we selected severely burned area of natural L. gmelinii forest in Great Xing’an Mountains as research object. The effect of severe burning on organic carbon and black carbon in soil aggregates was studied. The results showed that: 1) After severe burning, the contents of organic carbon and black carbon of surface soil significantly increased. Compared with contrast sample plot, soil organic carbon content in 0-5 cm soil layer increased by 41.56%, and black carbon content significantly increased by 123.69% (P0.05).2) Severe burning significantly increased the percentages of aggregates smaller than 0.25 mm and larger than 5 mm (P0.05), but the percentages of 0.25-5 mm all decreased in 0-5 cm soil layer.3) Compared with contrast sample plot, severe burning significantly increased the organic carbon content of aggregates smaller than 0.053 mm and larger than 5 mm by 127.27% and 177.6% (P0.05), respectively. Organic carbon content of 0.25-2 mm aggregates in three soil layers was lower than contrast sample plot tovarying degrees.The content of soil organic carbon in aggregates increased with the increase of particle size in the two kinds of forest, and showed a trend of decreasing with the increase of soil depth. 4) The characteristics of distribution of black carbon in aggregates were similar to organic carbon. After severe burning, black carbon of aggregates 5 mm,2-5 mm,0.053-0.25 mm and 0.053 mm increased by 4.92,4.19,1.06 and 0.44 g/kg in 0-5 cm soil layer, which was significantly different with contrast sample plot (P0.05). 5) The BC/SOC ratio ranged from 0.05 to 0.41 in two kinds of forest, and severe burning significantly increased BC/SOC ratio (P0.05). A significant correlation was found between organic carbon and black carbon contents in aggregates of each size class.