五台山土壤水稳性团聚体有机碳分布特征

为揭示五台山垂直带土壤不同形态团聚体有机碳的分布特征,以五台山垂直带土壤为研究对象,于2016年8月从高海拔至低海拔对亚高山草甸土、山地草甸土、棕壤、淋溶褐土、石灰性褐土样品进行采集,并且通过湿筛法和物理分组技术获得不同土壤类型中2,2~0.25,0.25~0.053,0.053mm水稳性团聚体,进一步分析了土壤及各级水稳性团聚体的总有机碳、颗粒有机碳(POC)和矿物结合有机碳(MOC)。结果表明:亚高山草甸土、山地草甸土和棕壤均以2mm团聚体为最多,达到总水稳性团聚体的45.13%。然而,淋溶褐土和石灰性褐土中分别以2~0.25mm和0.25~0.053mm团聚体为最多,分别达到33.79%和39.95%。随着海拔高度的降低土壤有机碳含量依次降低,且不同土壤类型中,2mm和2~0.25mm团聚体有机碳含量与其对应的土壤有机碳含量呈极显著正相关关系,相关系数分别为r2mm=0.986和r2~0.25mm=0.966(P0.01)。随着土壤团聚体粒径的减小,亚高山草甸土、山地草甸土、棕壤的POC含量呈现下降趋势,而淋溶褐土和石灰性褐土的POC含量呈现升高趋势。亚高山草甸土、山地草甸土、棕壤的MOC含量都以2mm团聚体为最大,淋溶褐土和石灰性褐土分别以2~0.25mm和0.25~0.053mm团聚体的MOC含量为最大。各土壤及团聚体中MOC的含量要明显大于POC的含量,而且在土壤和各级大团聚体中二者呈现正相关关系(P0.05)。此外,各土壤POC和MOC的含量与土壤有机碳含量也呈现正相关关系(P0.05)。因此,随着海拔高度的降低,各土壤团聚体组成由大团聚体向微团聚体转变,亚高山草甸土、山地草甸土、棕壤的碳截获能力强于淋溶褐土和石灰性褐土。

Distribution Characteristics of Organic Carbon in Soil Water-stable Aggregates of Wutai Mountain

To explore organic carbon distribution characteristics in different soil aggregates of Wutai Mountain vertical zone,the soil samples which including subalpine meadow soil,mountain meadow soil,brown soil,leached cinnamon soil and calcareous cinnamon soil were collected from high altitude to low altitude in August 2016.Water-stable aggregates in different levels (＞2 mm,2～0.25 mm,0.25～0.053 mm and ＜ 0.053 mm) of different type soils were harvested through wet-sieving method and physical fractionation technique,and the TOC,POC and MOC of all level aggregates and soils were further analyzed.The results showed that subalpine meadow soil,mountain meadow soil and brown soil all mainly composed by ＞2 mm aggregates,which accounted for 45.13％ of all water-stable aggregates.However,cinnamon soil and calcareous cinnamon soil were mainly composed by 2 ～ 0.25 mm and 0.25 ～ 0.053 mm aggregates respectively,reached 33.79％ and 39.95％.With the decrease of altitude,soil organic carbon content decreased.Besides,the organic carbon content of ＞2 mm and 2～0.25 mm aggregates in different type soils had a great significant positive correlation with the corresponding soil organic carbon content and the correlation coefficients were r＞2 mm =0.986,r2～0.25 mm =0.966 (P＜0.01).Although with the decrease of soil aggregates diameter,the POC contents of subalpine meadow soil,mountain meadow soil and brown soil decreased,and the POC contents of leached cinnamon soil and calcareous cinnamon soil increased.The MOC content of subalpine meadow soil,mountain meadow soil and brown soil were highest in ＞2 mm aggregates,and the MOC content of leached cinnamon soil,calcareous cinnamon soil were highest in 2～0.25 mm and 0.25～0.053 mm aggregates,respectively.The soil MOC content was significantly greater than the POC content,and these two showed a positive correlation in soils and all level macro-aggregates (P＜0.05).In addition,the content of POC and MOC in soils also showed a positive correlation with the content of soil organic carbon (P＜0.05).Therefore,the soil aggregates turned from macro-aggregates to micro-aggregates with the decrease of altitude,and the carbon capture ability of subalpine meadow soil,mountain meadow soil and brown soil was stronger than leached cinnamon soil and calcareous cinnamon soil.