中文摘要：

对落叶松人工纯林不同发育阶段幼龄林、中龄林、近熟林、成熟林及二代幼龄林土壤腐殖物质组分变化及其对酸度的影响进行研究，以次生林和一代幼龄林为对照，比较不同发育阶段落叶松人工林与天然次生林、一代幼龄林与二代幼龄林土壤有机质含量、腐殖物质组分特征的差异。结果表明：落叶松人工林从幼龄林到近熟林根际与非根际土壤有机质含量、胡敏酸含碳量、胡敏素含碳量随林龄的增大而增大；近熟林到成熟林根际与非根际土壤有机质含量、富啡酸含碳量和胡敏素含碳量随着林龄的增大而降低；土壤腐殖化程度（土壤中胡敏酸占全C的百分比）和土壤腐殖质中胡敏酸含碳量与富啡酸含碳量比值（HA／FA）为次生林大于幼龄林和近熟林；二代幼龄林与一代幼龄林相比，根际土壤有机质含量、富啡酸含碳量和胡敏素含碳量分别降低4．53％、35．8％和1．98％，非根际土壤有机质含量、胡敏酸含碳量、富啡酸含碳量和胡敏素含碳量分别提高46．44％、43．69％、47．45％和49．5％；土壤腐殖物质组分与酸度的相关关系随着年龄的变化而变化，并且不同发育阶段根际土壤腐殖物质组分与根际土壤活性酸（pH值）、交换性酸、水解性酸相关性密切。

英文摘要：

The research was made that the change of component of soil humic substances in larch plantations and its effects on the soil acidity at the different development stages （young stand, half-mature stand, near mature stand, mature stand and young stand in the second rotation）. The differences of soil organic matter content and the characteristics of component of humic substances between the larch plantations at different development stages and natural secondary forests, young stands in the first rotation and in the second rotation were compared. The results showed that soil organic matter content, the carbon content in humic acid and the carbon content in humin in rhizosphere and non-rhizosphere soil from young stand to near mature stand increased with stand ages grew; Soil organic matter content, the carbon content in fulvic acid and the carbon content in humin in rhizosphere and non-rhizosphere soil from near mature stand to mature stand decreased with stand ages grew; The humification degrees （the percentage of carbon content in humic acid in the total C） and the ratio of the carbon content in humic acid to the carbon content in fulvic acid in soil humic substances in the secondary forests were greater than those in the young stand and near mature stand. For the rhizosphere soil, the organic matter content, the carbon content in fulvic acid and the carbon content in humin decreased by 4.53 %, 35.8 % and 1.98 % in young stand in the second rotation, respectively, as compared with those in young stand in the first rotation. For the non-rhizosphere soil, organic matter content, the carbon content in humic acid, the carbon content in fulvic acid and the carbon content in humin increased by 46.44 %, 43.69 %, 47.45 % and 49.5 % in young stand in the second rotation, respectively, as compared with those in young stand in the first rotation. The relationship between component of soil humic substances and soil acidity changed with stand ages changed. In rhizosphere soil, the close relationship existed among compon