林农复合对沙地樟子松人工林土壤团聚体、有机碳及微生物生物量碳分配的影响

Allocation of soil aggregates,organic carbon and microbial biomass carbon affected by agroforestry modes in Pinus sylvestris var. mongolica plantations in sandy area

为探究林农复合对土壤团聚体、土壤有机碳、土壤微生物生物量碳的影响,在辽西地区选取樟子松-花生、樟子松-谷子、樟子松纯林(对照)为研究对象,对其土壤团聚体、团聚体有机碳、土壤微生物生物量碳以及土壤有机碳含量及其分布特征进行研究。结果表明:(1)研究区土壤团聚体以0.053~0.25 mm粒级为主,占团聚体总量的37%~45%,其中樟子松-谷子的大团聚体(>0.25 mm粒级)含量最高。(2)两种林农复合各粒级团聚体有机碳含量变化显著不同(P<0.05),樟子松-花生团聚体有机碳随粒径增大呈现"倒N"型分布,而樟子松-谷子土壤团聚体有机碳随粒径增大呈现"N"型分布。(3)0~20 cm表层土壤微生物生物量碳和有机碳含量大小顺序为:樟子松-谷子>樟子松纯林>樟子松-花生。(4)试验区土壤有机碳的积累主要受0.053~0.25 mm和>2 mm粒级团聚体含量的影响;另外,0~50 cm土壤剖面微生物生物量碳和有机碳相关分析表明,樟子松-谷子土壤微生物生物量碳与有机碳具显著相关性,而在樟子松-花生复合林地内无显著相关性;这说明不同营林措施对土壤有机碳和微生物的影响存在差异。综上,辽西地区樟子松-谷子复合措施有利于改善土壤结构,促进大团聚体的形成,对提高土壤保水、供肥能力,实现对土壤的保护和可持续利用具有较为明显的作用。

The objective of this study was to assess how agroforestry modes affect allocation of soil aggregates（SA）,organic carbon（SOC） and microbial biomass carbon（MBC）.We measured the contents of the SA,SOC and MBC in three modes：Pinus sylvestris var.mongolica（PS）,P.sylvestris var.mongolica-Arachis hypogaea（PA）,P.sylvestris var.mongolica-Setaria italica（PH） in Fujia Forest Farm,Northwest Liaoning.The results showed that（1） the aggregate composition was dominated by particles of 0.053-0.25 mm which accounted for 37%-45% of the total under the three modes and the proportion of soil aggregates with particles 〉0.25 mm was the highest in the PH.（2） The change pattern of organic carbon content in aggregates with aggregate size was significantly different between the two kinds of agroforestry（P〈0.05）.The distribution of organic carbon contents in soil aggregates with the increase of aggregate size exhibited an ＂upside-down N type＂ for PA and a ＂N＂ type for PH.（3） SOC and MBC in the top-layer soil（0-20 cm） of the three modes were in the order of PH〉 PS〉 PA.（4） The SOC accumulation was mainly influenced by the contents of aggregates of 0.053-0.25 mm and 〉2 mm.In addition,MBC was significantly correlated with SOC in 0-50 cm soil layer in the PH,but not in the PA.These results indicate that agroforestry modes can affect MBC and SOC contents.