Background and aims

Soil carbon (C) pools influence the global C balance of terrestrial ecosystems. Calcium (Ca) affects soil organic carbon (SOC) by mediating organic-mineral interactions. In this study, we aimed to elucidate the relationships among Ca forms, labile organic carbon (OC) fractions, carbon pool management indices and microbial communities.

Methods

We selected three soils with different calcium carbonate (CaCO₃) contents: black soil (4.29 g.kg⁻¹), fluvo-aquic soil (94.86 g.kg⁻¹) and loessial soil (133.87 g.kg⁻¹). We measured different Ca forms, microbial communities and labile OC fractions while calculating the soil carbon pool management indices.

Results

The results revealed a significant increase in major Ca forms and a significant decrease (P < 0.05) in labile OC fractions as well as carbon pool management indices in fluvo-aquic soil and loessial soil. The bacterial community diversity decreased, and the dominant bacteria and fungi shifted from oligotrophs to copiotrophs. Ca forms were significantly negatively (P < 0.05) correlated with the labile OC fraction and carbon pool management index (CPMI), and the bacterial community structure was closely related to bound to organic-Ca. Bacteria played a dominant role, and the symbiotic network robustness and complexity of the network modules were greater for bacteria than for fungi in calcareous alkaline soils.

Conclusions

The results suggested the existence of interactions between Ca forms, labile OC fractions, the CPMI and microbial communities in calcareous alkaline soils. Ca affects the labile OC fractions, which act on the CPMI and change the community composition of microbial (bacterial communities), influencing the SOC content.

中文翻译：

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钙形式通过介导钙质碱性土壤中不稳定的有机碳组分、碳库管理指数和微生物群落来影响土壤有机碳

 背景和目标

土壤碳 （C） 库影响陆地生态系统的全球碳平衡。钙 （Ca） 通过介导有机矿物相互作用来影响土壤有机碳 （SOC）。在本研究中，我们旨在阐明 Ca 形式、不稳定有机碳 （OC） 组分、碳库管理指数和微生物群落之间的关系。

 方法

我们选择了 3 种不同碳酸钙 （CaCO₃） 含量的土壤：黑土 （4.29 ^g.kg−1）、潮土 （94.86 g.kg⁻¹） 和黄土 （133.87 g.kg⁻¹）。在计算土壤碳库管理指数的同时，我们测量了不同的 Ca 形式、微生物群落和不稳定的 OC 分数。

 结果

结果显示，潮土和黄土中主要 Ca 形式的显著增加，不稳定的 OC 组分以及碳库管理指数显著减少 （P < 0.05）。细菌群落多样性降低，优势细菌和真菌从寡营养生物转变为 copiotrophs。Ca型与不稳定的OC分数和碳库管理指数（CPMI）呈显著负相关（P < 0.05），细菌群落结构与有机Ca结合密切相关。细菌起主导作用，在石灰质碱性土壤中，细菌的共生网络稳健性和网络模块的复杂性大于真菌。

 结论

结果表明，钙质碱性土壤中存在 Ca 形式、不稳定的 OC 组分、CPMI 和微生物群落之间的相互作用。Ca 影响不稳定的 OC 组分，这些组分作用于 CPMI 并改变微生物（细菌群落）的群落组成，从而影响 SOC 含量。