摘要:森林植被与土壤微生物作为森林生态系统的重要组成部分，它们之间的相互作用对维持森林生态系统功能和稳定性起着重要作用。以往多在天然草地和森林生态系统开展植物多样性与土壤微生物多样性关系的研究，但人工构建的多树种混交林生态系统中树种多样性对土壤微生物群落组成的影响及其机制尚不完全清楚。因此，以南亚热带人工块状造林后自然恢复形成的多树种混交森林生态系统为研究对象，利用高通量测序技术研究了随树种丰富度（1-10种）变化土壤细菌和真菌多样性的变化规律及主要影响因子。结果表明，随树种丰富度增加，土壤真菌α多样性显著提高，但土壤细菌α多样性差异不显著；不同树种丰富度梯度间土壤细菌和真菌的群落结构组成均差异显著；Pearson相关分析表明土壤细菌α多样性主要受土壤pH和土壤铵态氮影响，而土壤pH和有效磷是土壤真菌α多样性的主要影响因子。距离冗余分析（db-RDA）表明，对土壤细菌群落组成产生显著影响的环境因子分别为土壤pH、硝态氮和芳香碳组分，而土壤有机碳、硝态氮、细根生物量和氧烷基碳组分是影响土壤真菌群落组成的主要因子。本研究的结果说明了南亚热带人工林不同树种混交后形成多树种混交林生态系统的过程中，树种组成和多样性的变化通过改变土壤理化性状和根系生物量对土壤微生物群落组成有显著影响，为制定该区域人工林通过树种丰富度合理组配调控提升地下生物多样性及生态系统功能的经营策略提供了科学依据。



Abstract:Forest vegetation and soil microorganisms are important components of forest ecosystems, and their interaction plays an important role in maintaining the function and stability of these ecosystems. The relationship between diversities of plants and soil microbes has been studied extensively in natural grasslands and forest ecosystems. However, the effect of tree species diversity on soil microbial community composition and its mechanism in the planted forest ecosystem with multiple tree species remains unclear. Therefore, this study focused on the mixed planted forest ecosystem through close-to-nature restoration in south subtropical China, and examined the effect of tree species diversity (1-10 species) on the diversity of soil bacteria and fungi and the main influencing factors, using the high-throughput Illumina sequencing method. The results showed that the α-diversity of the soil fungi increased significantly with the increase in tree species diversity; however, α-diversity of the soil bacteria did not change significantly with the increase in tree species diversity. The community composition of soil bacteria and fungi differed significantly among the different tree species diversity levels. The Pearson's correlation analysis showed that the soil bacterial α-diversity was mainly affected by soil pH and NH₄⁺-N, whereas soil pH and available phosphorus were the main factors affecting the soil fungal α-diversity. Distance-based redundancy analyses showed that soil pH, NO₃^--N, and aromatic C were the main environmental factors affecting the soil bacterial community composition, whereas soil organic carbon, NO₃^--N, fine root biomass, and O-alkyl C were the main factors affecting the soil fungal community composition. Our study indicated that tree species diversity had a significant influence on the soil microbial community by changing the physical and chemical properties of the soil and the root biomass in the mixed planted forest ecosystem with different tree species in this south subtropical region. The study provides a basis for decision-making for increasing ecosystem function through an appropriate assembly of tree species diversity in subtropical planted forests.





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