Lan Jiacheng, Wang Shasha, Wang Junxian, Qi Xue, Long Qixia, Huang Mingzhi
School of Karst Science/State Engineering Technology Institute for Karst Desertification Control, Guizhou Normal University, Guiyang, China.
Front Microbiol. 2022 Jun 27;13:901126. doi: 10.3389/fmicb.2022.901126. eCollection 2022.
Soil microbes regulate the carbon cycle and affect the formation and stabilization of soil aggregates. However, the interactions between the soil microbial community and soil organic carbon (SOC) fractions, organic carbon (OC) content in aggregates, and soil aggregate stability after afforestation are remain poorly understood. In our study, we investigated SOC fractions in bulk soil, aggregate-associated OC content, soil aggregate stability, and soil bacterial community with high-throughput 16S rRNA sequencing at sites representing natural secondary forest (NF) and managed forest (MF), with cropland (CL) as reference in a degraded karst region of Southwest China. Our results showed that afforestation remarkably increased the SOC fraction and OC content in aggregates, the mean weight diameter (MWD), and the mean geometric diameter (GMD). The most dominant bacterial phyla detected were , , , and across all soils. Afforestation remarkably altered the relative abundances of most of the dominant soil bacteria at the phylum, class, and order levels. Interestingly, such changes in the abundance of soil bacteria taxa had significantly effects on SOC fraction, aggregate-associated OC content, MWD, and MGD. The abundance of dominant bacterial taxa such as , , , , ; , , , , , , , and not only remarkably increased but also had significant positive effects on SOC fractions and aggregate-associated OC content after afforestation. Moreover, MWD and MGD were positively correlated with the relative abundance of , , , , and . Results indicated the importance of certain soil bacteria for regulating SOC storage and soil aggregate stability. We concluded that afforestation on cropland could alter the abundance of soil bacteria, and these changes modulate the stability of soil aggregates and SOC fractions.
土壤微生物调节碳循环，并影响土壤团聚体的形成和稳定性。然而，造林后土壤微生物群落与土壤有机碳（SOC）组分、团聚体中有机碳（OC）含量以及土壤团聚体稳定性之间的相互作用仍知之甚少。在我们的研究中，我们在中国西南退化喀斯特地区，以农田（CL）为参照，利用高通量16S rRNA测序技术，调查了代表天然次生林（NF）和人工林（MF）的样地中，土壤中SOC组分、与团聚体相关的OC含量、土壤团聚体稳定性以及土壤细菌群落。我们的结果表明，造林显著增加了团聚体中的SOC组分和OC含量、平均重量直径（MWD）和平均几何直径（GMD）。在所有土壤中检测到的最主要细菌门为 、 、 和 。造林显著改变了大多数优势土壤细菌在门、纲和目水平上的相对丰度。有趣的是，土壤细菌类群丰度的这种变化对SOC组分、与团聚体相关的OC含量、MWD和MGD有显著影响。造林后， 、 、 、 、 ； 、 、 、 、 、 、 和 等优势细菌类群的丰度不仅显著增加，而且对SOC组分和与团聚体相关的OC含量有显著的正影响。此外，MWD和MGD与 、 、 、 和 的相对丰度呈正相关。结果表明某些土壤细菌对调节SOC储存和土壤团聚体稳定性的重要性。我们得出结论，农田造林可以改变土壤细菌的丰度，而这些变化会调节土壤团聚体的稳定性和SOC组分。
