枯落物输入变化对云南松林土壤微生物群落结构及功能影响

Influence of litter input alterations on the soil microbial community structure and function in Pinus yunnanensis forest

关键词:  云南松, 枯落物, 土壤细菌, 土壤真菌, 功能预测

Key words:  Pinus yunnanensis (Yunnan pine), litter, soil bacteria, soil fungi, functional predictionPinus yunnanensis (Yunnan pine), litter, soil bacteria, soil fungi, functional prediction

摘要:

为探究云南松林枯落物输入变化对土壤微生物群落结构和功能的影响及其主要驱动因素,该研究应用枯落物添加与去除实验(DIRT),设置枯落物正常输入(对照,CK)、去除根系(NR)、去除枯落物(NL)、双倍枯落物(DL)、无输入(NI)及去除有机层和A层(OA)6种处理,并利用Illumina HiSeq测序技术结合PICRUSt2和FUNGuild功能预测,分析不同枯落物输入对云南松林地土壤微生物群落结构及功能的影响。结果表明:(1)不同枯落物处理间的细菌和真菌群落组成表现出一定的差异且真菌群落差异较大,去除枯落物处理显著增加真菌担子菌门和红菇属的相对丰度,而去除枯落物、无输入及去除有机层和A层处理显著降低真菌被孢霉门和被孢霉属的相对丰度。(2)去除根系和无输入处理增加了细菌α多样性(Ace、Chao),而去除枯落物和根系(NR、NL、NI)处理显著降低真菌α多样性(Shannon)且减少枯落物输入显著影响真菌β多样性。(3)枯落物处理显著改变了真菌功能群结构。去除枯落物和去除根系处理显著增加外生菌根真菌丰度,而减少枯落物输入(NR、NL、NI、OA)处理则显著降低内生-凋落物腐生-土壤腐生-未定义腐生菌丰度; 去除有机层和A层处理显著增加杜鹃花类菌根真菌丰度。(4)相关性分析结果显示,土壤有机碳、全氮和pH与细菌群落结构和功能变化密切相关,而全磷、全钾和pH与真菌群落结构和功能变化密切相关。综上认为,与添加枯落物相比,枯落物输入减少对土壤微生物群落结构、多样性和功能产生了更为显著的影响,尤其对真菌的影响较大,而对细菌的影响较小,这些影响与土壤碳、氮输入及土壤化学性质的改变紧密相关。该研究结果对于科学预测全球变化和人类活动背景下的土壤生态系统功能和稳定性具有重要意义。

Abstract:

To explore the influence of litter input alterations on the soil microbial community structure and function in a Pinus yunnanensis forest in central Yunnan Plateau, and their main driving factors, the detritus imput and removal treatments(DIRT)was applied. Six different litter treatments were established: normal litter imput(control, CK), no root(NR), no litter(NL), double litters(DL), no input(NI), and organic and A horizons removed(OA). The effect of different litter imputs on the soil microbial community structure and function in P. yunnanensis forest was investigated by utilizing Illumina HiSeq sequencing technology combined with PICRUSt2 and FUNGuild functional prediction. Furthermore, redundancy analysis was employed to elucidate the driving factors behind these changes in the soil microbial community structure and function. The results were as follows:(1)There were differences in the composition of bacterial and fungal communities among different litter treatments, with significant differences in the fungal communities. The NL treatment significantly increased the relative abundance of Basidiomycota and Russula, while the NL, NI and OA considerably decreased the relative abundance of Mortierellomycota and Mortierella.(2)The litter treatments significantly affected the α diversity of the bacteria and fungi, as well as the fungal β diversity. The NR and NI treatments increased the bacterial α diversity(Ace and Chao), while the NR, NL and NI treatments significantly decreased the fungal α diversity(Shannon), and reducing the CK had a greater impact on the fungal β diversity.(3)The litter treatments markedly altered the fungal functional groups. Moreover, the NL and NR treatments enhanced the ectomycorrhizal abundance, while the NR, NL, NI and OA treatments decreased the abundance of endophyte-litter saprotroph-soil saprotroph-undefined saprotroph; the OA treatment significantly increased the ericoid mycorrhizal abundance.(4)Correlation analysis results revealed that soil organic carbon, total nitrogen and pH were closely related to the structural and functional changes of the bacterial community in Pinus yunnanensis forest, while total phosphorus, total potassium and pH were closely related to the structural and functional changes of the fungal community. In conclusion, compared to the litter addition treatments, the reduction of litter imput has a more significant effect on the soil microbial community structure, diversity and function, particularly on the fungi compared to the bacteria. These effects are closely associated with the alterations of soil carbon and nitrogen inputs and chemical properties. This study provides critical insights for predicting soil ecosystem functionality and stability under global changes and human activities.