Aims

This study was conducted over 10 years using an open top chamber experiment in the Sanjiang Plain to explore the impact of environmental parameters and bacterial community composition and structure under long-term conditions of elevated CO₂ concentrations (eCO₂, 550 μmol·mol⁻¹).

Methods

Illumina sequencing of 16S rRNA was used to determine soil bacterial communities over the long-term in the Sanjiang Plain. Vegetation characteristics and soil properties were also investigated.

Results

Dominant bacterial group was Proteobacteria, accounting for 23.52–39.03%, while there were remarkable changes in the bacterial community composition. eCO₂ increased the relative abundance of Subgroup_6 and decreased those of AD3 and Candidatus_Udaeobacter. These variations might be related to gene functions. A redundancy analysis indicated that there was a strong relationship between dominant bacterial phyla and environmental factors (photosynthetic rate, aboveground biomass and stomatal conductance). Structural equation model (SEM) showed that eCO₂ and year both affected the soil bacterial community. In contrast, the short-term had greater impacts on the bacterial community under eCO₂ compared with the long-term via indirect effects on vegetation and soil characteristics.

Conclusions

eCO2 affect soil bacterial community through indirect effects on soil nutrient content and vegetation characteristics in the short-term whereas showed adaptability to eCO2 in the long term.

中文翻译：

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10年大气CO2升高对东北三江平原土壤细菌群落结构的影响

宗旨

本研究在三江平原使用开顶室实验进行了 10 多年，以探索在 CO ₂浓度升高（eCO ₂ , 550 μmol·mol ^-1）。

方法

Illumina 16S rRNA 测序用于确定三江平原长期土壤细菌群落。还调查了植被特征和土壤性质。

结果

优势菌群为变形菌，占23.52%～39.03%，菌群组成发生显着变化。eCO ₂增加了 Subgroup_6 的相对丰度，降低了 AD3 和 Candidatus_Udaeobacter 的相对丰度。这些变异可能与基因功能有关。冗余分析表明优势细菌门与环境因素（光合速率、地上生物量和气孔导度）之间存在很强的相关性。结构方程模型（SEM）表明，eCO ₂和年份均影响土壤细菌群落。相比之下，短期对 eCO ₂下的细菌群落影响更大 与长期通过对植被和土壤特征的间接影响相比。

结论

eCO2 在短期内通过对土壤养分含量和植被特征的间接影响来影响土壤细菌群落，而在长期内对 eCO2 表现出适应性。