Science Research Fund Project of Yunnan Provincial Department of Education（No.2019Y0108），Natural Science Foundation Item of Yunnan Provincial Scienceand Technology Department (No.2006D0039M) and The Fourth Survey of Forest Management Inventory in Yunnan Province-Forest Soil Survey (No.00000000038－407)
云南省森林生态系统在全球碳循环及平衡中具有不可替代的作用，但其森林土壤腐殖质组分特征及其影响因素尚不十分清楚。基于云南省不同林区采集的88个表层土样，通过描述性统计和回归分析量化了海拔、土壤类型、坡向和坡度、年均温和年降水量对土壤腐殖质组分分布影响的相对重要性，探讨云南省森林土壤腐殖质组分分布特征。结果表明：云南省森林土壤表层有机碳含量为8.40～199.73 g·kg-1，平均含量为51.37 g·kg-1，土壤可提取腐殖质碳含量为2.54～84.02 g·kg-1，平均含量为24.52 g·kg-1；胡富比均值小于1，土壤腐殖质聚合度较低；土壤腐殖质组分分布特征总体表现为滇西北、滇东北部较高，滇中、滇南部较低；土壤类型、海拔、年均温是影响云南省森林土壤腐殖质组分含量的主导因子，各因素的贡献程度总体呈现为土壤类型最高，其次是年均温、海拔，这说明土壤类型对森林表层土壤腐殖质的积累起重要作用。
[Objective] Yunnan Province is rich in forest resources, thus posing an important part of China's forest carbon pool. Its forest ecosystem plays an irreplaceable role in the global carbon cycle and balance, and its organic carbon pool in the forest soil does too in regulating the global carbon balance and slowing down the rising concentration of atmospheric chamber gas. Though soil humus is known to be the main body of soil carbon, it is still unclear as to characteristics of its composition and influencing factors. Therefore, it is of great significance to strengthen the study of composition of the forest soil humus and its influencing factors to the efforts of regulating forest soil carbon balance and improving soil fertility.[Method] A total of 88 soil samples were collected from the topsoil layers of different forest zones in Yunnan province. Environmental factors of the sampling sites, such as soil type, latitude and longitude, elevation, slope degree and slope aspect, were measured through field investigations. The soil samples were analyzed in lab for contents of soil carbon and soil humus and its components, of which regression analysis and descriptive statistics were employed to quantify relative contributions of elevation, soil type, slope degree, slope aspect, annual mean precipitation and annual mean temperature to the variation of soil humus composition. In the end, soil humus composition and distribution in the forest soils of Yunnan were characterized.[Result] Results show:in the top soils of the forests, SOC content varied in the range from 8.40 to 199.73 g·kg-1, with a mean of 51.37 g·kg-1; HE-C content in the range from 2.54 to 84.02 g·kg-1, with a mean of 24.52 g·kg-1; HA-C content in the range from 0.99 to 33.64 g·kg-1, with a mean of 9.35 g·kg-1; FA-C content in the range from 1.40 to 57.16 g·kg-1, with a mean of 15.17 g·kg-1; and H/F in the range from 0.17 to 4.59, with a mean of 0.78; soil humus in the samples was fairly low in polymerization degree, with C/N ranging from 4.68 to 41.72 and averaged to be 14.25. The contributions of soil type, elevation and annual mean temperature to soil humus composition were significant(P<0.01 or 0.05), but those of annual precipitation, slope degree and slope aspect were not so significant(P<0.05). The environmental factors varied in explanation of the spatial variation of total organic carbon, extractable humic carbon, humic acid carbon, fulvic acid carbon, and carbon-nitrogen ratio in the soil with soil type explaining 30.1%, 29.6%, 30.9%, 24.3% and 11.5%; annual mean temperature doing 22.2%, 19.5%, 13.7%, 18.8% and 18.0%; elevation doing 13.3%, 9.4%, 11.1%, 8.7% and 13.9%, respectively.[Conclusion] The content of soil organic carbon in the forest soils of Yunnan is found to be relatively high in the northeast and northwest parts of the province, and relatively low in the south and central parts. Soil type, elevation and average mean temperature are the key factors regulating spatial variability of the soil humus in the forests of Yunnan Province. In terms of contribution degree, the factors exhibit an order of soil type > annual mean temperature > elevation. Soil type plays an important role in the accumulation of humus in the forest surface soil.
周红,何欢,肖蒙,何忠俊.云南省森林土壤腐殖质组分特征及影响因素[J].土壤学报,2021,58(4):1008-1017. DOI:10.11766/trxb202003240513 ZHOU Hong, HE Huan, XIAO Meng, HE Zhongjun. Composition of Humus in Forest Soils of Yunnan Province, China and Its Influencing Factors[J]. Acta Pedologica Sinica,2021,58(4):1008-1017.复制