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随着全球气候的变化,森林土壤有机碳作为碳库的重要组成部分,成为森林碳循环研究的重点之一。以北京松山8块不同林龄天然油松林样地为研究对象,通过方差分析及方差分解的方法分析不同林龄土壤有机碳、碳密度的分布特征及影响因素,结果表明:(1)该地区油松林土壤碳含量平均值为20.61 g·kg~(-1);土壤碳密度为153.67 t·hm~(-2),低于中国森林生态系统平均值(193.55 t·hm~(-2))。同一林龄土壤有机碳含量随土壤深度的增加而显著降低(P<0.05)。(2)在0~50 cm土层,不同林龄土壤有机碳含量普遍存在显著差异性(P<0.05),在50~100 cm层差异不显著。随着林龄增大,土壤碳密度显著增加(P<0.05)。各土层土壤碳密度与土壤碳含量随林龄变化趋势并不一致。中龄林、近熟林、成熟林、过熟林土壤有机碳均集中分布在较浅表层(0~30 cm),分别占总土层有机碳含量的81.1%、83.6%、82.5%、81.7%。(3)土壤各层碳含量、碳密度与土壤含水量呈显著相关(P<0.001,P<0.05),各层土壤碳含量与土壤容重呈显著负相关(P<0.05)。各样地土壤平均碳含量(ACC)、碳密度(ACD)与地形因子、林分特征因子以及土壤因子之间普遍存在显著关联。地形模型、林分特征模型、土壤模型对ACC、ACD方差的解释程度具有一定的差异性。总体而言,林分特征模型能较好地解释ACD方差,地形因子模型、土壤因子模型对结果解释程度相对偏低。林分特征模型和土壤模型结合起来能较好地解释ACC方差,地形因子模型对结果解释程度不高。
As global climate changes, forest soil organic carbon as an important part of carbon pool has become one of the focuses of forest carbon cycle research. Taking 8 natural forest stands of Pinus sylvestris var.mongholicus in Songshan, Beijing as the research object, the distribution characteristics and influencing factors of soil organic carbon and carbon density at different stand ages were analyzed by analysis of variance and variance. The results showed that: (1) The average soil carbon content in Pinus tabulaeformis forest was 20.61 g · kg -1 and the soil carbon density was 153.67 t · hm -2, which was lower than the average of forest ecosystem in China (193.55 t · hm -2) ). Soil organic carbon at the same stand age decreased significantly with soil depth (P <0.05). (2) In 0 ~ 50 cm soil layer, the soil organic carbon content in different age groups was significantly different (P <0.05), but no significant difference in 50 ~ 100 cm layer. With increasing age, soil carbon density increased significantly (P <0.05). Soil carbon density and soil carbon content in different soil layers vary with age. Soil organic carbon in middle-aged, near-mature, mature and mature forests mainly distributed in the shallow layer (0-30 cm), accounting for 81.1%, 83.6%, 82.5% and 81.7% of the total soil organic carbon content %. (3) There was a significant correlation between soil carbon content and soil water content (P <0.001, P <0.05). There was a significant negative correlation between soil carbon content and soil bulk density (P <0.05). The average soil carbon content (ACC) and carbon density (ACD) were significantly correlated with the topographic factors, the stand characteristic factors and the soil factors. Topographical models, stand models, and soil models have some differences in the interpretation of ACC and ACD variance. Generally speaking, the stand model can explain the variance of ACD well, the topographic factor model and the soil factor model explain the result relatively low. The combination of stand model and soil model can better explain the ACC variance, and the terrain factor model does not explain the result to a high degree.