四川盆地西南缘不同林分类型土壤团聚体稳定性及有机碳组分特征

Soil Aggregate Stability and Characteristics of Organic Carbon Components in Three Forests of the Southwest Edge of Sichuan Basin

为探明林分类型差异对土壤水稳性团聚体分布格局及其稳定性、有机碳组分的影响,测定分析了四川盆地西南缘巨桉人工林、杉木人工林、马尾松次生林土壤水稳性团聚体的分布格局、团聚体平均质量直径、团聚体破坏率、大团聚体比重及有机碳组分含量。结果表明:(1)3种林分土壤水稳性团聚体含量均以大团聚体(>0.25mm)为主。不同林分对水稳性团聚体分布格局存在差异,巨桉人工林集中在0—20cm土层的>5,0.5~0.25mm和20—40cm的≤0.25mm粒径;杉木人工林集中在0—20cm土层的>5,0.5~0.25mm和20—40cm土层的1~0.5,0.5~0.25mm粒径;马尾松次生林集中在0—20cm的≤0.25mm和20—40cm土层的>5mm粒径。20—40cm土层不同林分土壤团聚体稳定性差异显著,马尾松林的MWD、R0.25、PAD最高,根据Bissonnais及国际土壤团聚体稳定性分级标准,3种林分土壤水稳性团聚体均处于不稳定水平(0.4≤MWD<0.8)。(2)HUC含量马尾松显著高于巨桉,0—20cm土层马尾松的土壤腐殖化程度最高,20—40cm土层杉木最高。(3)不同林分团聚体稳定性与SOC组分的关系因林分类型的差异不同,总体上表现为MWD与SOC、FAC、HUC存在显著相关关系,土壤SOC含量能够促进土壤团聚过程及其稳定性,FAC、HUC含量的作用较大。总之,巨桉人工林、杉木人工林、马尾松次生林土壤团聚体稳定性、SOC组分含量及两者之间的关系存在显著差异,不同林分其影响机制不同。研究结果为准确评价该区域不同林分所发挥的生态系统功能提供重要依据。

In order to research the effect of forest types on the distribution pattern of soil water stable aggregate,its stability,the organic carbon component and their relationships,the distribution pattern of soil water stable aggregate,the average aggregate diameter,percentage of aggregate disruption,macroaggregate proportion and the content of organic carbon component were determined in the Eucalyptus grandi plantation,Cunninghamia Lanceolata plantation and Pinus massoniana secondary forest in Southwest Edge of Sichuan Basin,the results showed that:(1)The soil water stable aggregates in the three forests were mainly macroaggregates(>0.25 mm).The water stability of aggregate distribution pattern was different in the three forests,the water stable aggregates of>5,0.5~0.25 mm in 0-20 cm soil layer,and<0.25 mm of 20-40 cm soil layer were dominant for Eucalyptus grandi plantation,and Cunninghamia Lanceolata plantation was focused by>5,0.5~0.25 mm in 0-20 cm soil layer,and 1~0.5,0.5~0.25 mm in 20-40 cm soil layer,and≤0.25 mm in 0-20 cm soil layer,and>5 mm in 20-40 cm soil layer for Pinus massoniana secondary forest.The difference of soil aggregate stability was significant for different forest types in 20-40 cm soil layer,the MWD,R 0.25,PAD of Pinus massoniana secondary forest were highest.According to the Bissonnais and international soil aggregate stability classification standard,the soil aggregates could not reach the stable level(0.4≤MWD<0.8)for the three forests.(2)The content of HUC in the Pinus massoniana secondary forest was significantly higher than Eucalyptus grandi plantation,and the soil humification degree of Pinus massoniana secondary forest was the highest in 0-20 cm soil layer,while Cunninghamia Lanceolata plantation was the highest in 20-40 cm.(3)The relationships between aggregate stability and organic carbon components in three forests was different,and a significant correlation was found among MWD,SOC,FAC,and HUC.Soil organic carbon could promote soil agglomeration process and its stability,and FAC,FAC and HUC played the significant roles.In short,the soil aggregate stability,organic carbon contents and their relationships in the Eucalyptus grandi plantation,Cunninghamia Lanceolata plantation and Pinus massoniana secondary forest were significant differences,the influencing mechanisms were different.These results could provide theoretical basis for the accurate evaluation of the ecosystem function of different forest types in this region.