凋落物与蚯蚓对杨树人工林土壤有机碳组成的影响

Effects of litter and earthworm on soil organic carbon composition of poplar plantation

为揭示杨树叶凋落物和蚯蚓对杨树人工林土壤有机碳的影响机制,以杨树人工林为研究对象,选取杨树叶凋落物和蚯蚓2种影响因子,设置6个不同处理,研究杨树凋落物不同施用方式及接种蚯蚓对土壤有机碳及不同活性有机碳的影响.结果表明:与对照处理(CK)相比,杨树叶凋落物表施和接种蚯蚓使土壤有机碳(SOC)增加1.86%~17.12%;而凋落物混施使SOC含量增加16.37%.与CK相比,其他5个处理活性有机碳各指标的含量均有不同程度的增加,其中,轻组有机碳(LFOC)含量增加最多(109.36%),可溶性有机碳(DOC)最多增加了32.65%,热水提取态碳(HWEC)最多增加了27.78%.凋落物不同施加方式对有机碳的影响有显著的差异,相比于凋落物表施处理(T1和T4),混施处理(T2和T5)的DOC、HWEC、微生物生物量碳(MBC)、颗粒有机碳(POC)和LFOC含量均有一定的增加,其中HWEC增加最多(12.43%).土壤有机碳活性大小的顺序为T4>T5>T1>T2>T3>CK.在同时接种蚯蚓的处理中(T3、T4和T5),凋落物的不同施加方式也对活性有机碳的含量产生了影响,除酸提取态碳(AEC)和易氧化有机碳(ROC)外,其余指标均表明凋落物的混施比表施更能提高有机碳的含量.总体来看,杨树叶凋落物表施和混施处理均能增加土壤中活性有机碳的含量,且混施处理比表施处理效果更好;土壤中的蚯蚓有利于活性有机碳含量的增加.

In order to reveal the influence mechanism of leaf litter and earthworm on soil organic carbon in poplar plantation,2 kinds of influence factors,namely poplar leaf litter and earthworm,were applied in poplar plantation by 6 treatments.The results showed that surface application of poplar leaf litter and earthworm inoculation increased soil organic carbon(SOC)by 1.86%—17.12%compared with the control(CK);mixed application of litter increased SOC content by 16.37%.Compared with CK,activated organic carbon contents in other 5 treatments also increased to varying degrees.Among them,light fraction organic carbon(LFOC)content surged the most by 109.36%,followed by 32.65%increases from dissolved organic carbon(DOC)and 27.78%increases from hot water extractable carbon(HWEC).The impact of litter application method on organic carbon varied significantly.Compared with surface application of litter(T1 and T4),contents of DOC,HWEC,microbial biomass carbon(MBC),particulate organic carbon(POC)and LFOC in mixed application treatments(T2 and T5)all enhanced to certain extent,among which HWEC increased the most(12.43%).The order of soil organic carbon activity in different treatments was T4>T5>T1>T2>T3>CK.Among treatments comprising both litter application and earthworm inoculation(T3,T4 and T5),litter application methods affected the content of activated organic carbon.Apart from acid extracted carbon(AEC)and readily oxidation carbon(ROC),all other indicators were more likely to be enhanced by mixed applied litter than surface applied.In general,surface application and mixed application of poplar leaf litter both increase active organic carbon content,and the latter surpasses the former;earthworms are conducive to improving active organic carbon content.