State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling, 712100, China; Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, 712100, China.
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling, 712100, China.
J Environ Manage. 2024 Nov;370:122802. doi: 10.1016/j.jenvman.2024.122802. Epub 2024 Oct 4.
Forest soil microbes play a crucial role in regulating atmospheric-soil carbon fluxes. Environmental heterogeneity across forest types and regions may lead to differences in soil CO and CH emissions. However, the microbial mechanisms underlying these emission variations are currently unclear. In this study, we measured CO and CH emissions of Robinia pseudoacacia forests along a north-south transect in the Loess Plateau. Using metagenomic sequencing, we investigated the structural and functional profiles of soil carbon cycling microbial communities. Results indicated that the forest CO emissions of Robinia pseudoacacia was significantly higher in the north region than in the south region, while the CH emission was oppositely. This is mainly attributed to changes in gene abundance driven by soil pH and moisture in participating carbon degradation and methane oxidation processes across different forest regions. The gene differences in carbon fixation processes between regions primarily stem from the Calvin cycle, where the abundance of rbcL, rbcS, and prkB genes dominates microbial carbon fixation in forest soils. Random forest models revealed key genes involved in predicting forest soil CO emissions, including SGA1 and amyA for starch decomposition, TYR for lignin decomposition, chitinase for chitin decomposition, and pectinesterase for pectin decomposition. Microbial functional characterization revealed that interregional differences in CH emissions during methane metabolism may originate from methane oxidation processes, and the associated gene abundances (glyA, ppc, and pmoB) were key genes for predicting CH emissions from forest soils. Our results provide new insights into the microbial mechanisms of CO and CH emissions from forest soils, which will be crucial for accurate prediction of the forest soil carbon cycle in the future.
森林土壤微生物在调节大气-土壤碳通量方面起着至关重要的作用。森林类型和区域的环境异质性可能导致土壤 CO 和 CH 排放的差异。然而，这些排放变化的微生物机制目前尚不清楚。在本研究中，我们沿着黄土高原的南北向样带测量了刺槐林的 CO 和 CH 排放。通过宏基因组测序，我们研究了土壤碳循环微生物群落的结构和功能特征。结果表明，刺槐林的 CO 排放北部地区显著高于南部地区，而 CH 排放则相反。这主要归因于不同森林区域土壤 pH 和水分变化驱动的参与碳降解和甲烷氧化过程的基因丰度变化。不同区域间碳固定过程的基因差异主要源于卡尔文循环，其中 rbcL、rbcS 和 prkB 基因的丰度主导着森林土壤中微生物的碳固定。随机森林模型揭示了参与预测森林土壤 CO 排放的关键基因，包括淀粉分解的 SGA1 和 amyA、木质素分解的 TYR、几丁质分解的几丁质酶和果胶分解的果胶酯酶。微生物功能特征表明，甲烷代谢过程中 CH 排放的区域间差异可能源于甲烷氧化过程，相关基因丰度（glyA、ppc 和 pmoB）是预测森林土壤 CH 排放的关键基因。我们的研究结果为森林土壤 CO 和 CH 排放的微生物机制提供了新的见解，这对于未来准确预测森林土壤碳循环至关重要。
