Soil acidification due to long-term tea plantations is a pervasive problem that may affect soil organic carbon (SOC) preservation by altering organo-mineral interactions. Nevertheless, how iron (Fe) minerals and microbes regulate SOC stabilization with increasing years of tea plantation establishment remains unclear. By analyzing the dynamic changes of SOC, Fe fractions and Fe oxide-bound OC (Fe–OC) pools, and associations with microbial communities over tea plantation establishment time-series (1, 7, 16, 25, and 42 years), this study explored the roles of coupled Fe oxides and microbial communities in regulating SOC accumulation and stabilization. The SOC levels significantly increased with years of tea plantation, accompanied by increases in the proportions of macroaggregates, poorly crystalline Fe oxides and organically complexed Fe, but soil pH decreased sharply. The increased soil Fe–OC pool and molar C:Fe ratios were positive correlated with SOC and macroaggregates, indicating that SOC was preserved by physic-chemical protection. Furthermore, these changes induced decreases in microbial biomass C and bacterial diversity with years of tea plantation. The relative abundance of A-strategists (i.e., Acidobacteria, Actinobacteria, Chloroflexi) increased concurrently, with an opposite trend for Y-strategists, suggesting tea plantation-induced environmental changes shifted the Y-strategists towards the predominance of A-strategists. Collectively, these findings provide new insights into the role of Fe oxides and microbial life history traits in SOC accumulation and stabilization in the progression of tea plantation establishment, including (i) physic-chemical protection of SOC through formation of Fe–OC by complexation; and (ii) regulation of the microbial community diversity and composition, especially bacterial life strategies. These results are of great implications for better predicting and accurately controlling the response of OC pools in tea plantations to future changes and disturbances and for maintaining regional C balance.

中文翻译：

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茶园时间序列中耦合的氧化铁和微生物介导的土壤有机碳稳定


长期茶园导致的土壤酸化是一个普遍存在的问题，它可能会通过改变有机矿物相互作用来影响土壤有机碳 （SOC） 的保存。然而，随着茶园建立时间的增加，铁 （Fe） 矿物和微生物如何调节 SOC 稳定仍不清楚。通过分析 SOC、Fe 馏分和氧化铁结合 OC （Fe-OC） 池的动态变化，以及与茶园建立时间序列 （1、7、16、25 和 42 年） 上微生物群落的关联，本研究探讨了偶联的 Fe 氧化物和微生物群落在调节 SOC 积累和稳定中的作用。土壤有机碳水平随着茶叶种植的年限而显著增加，伴随着大团聚体、低结晶性氧化铁和有机络合铁比例的增加，但土壤pH值急剧下降。土壤 Fe-OC 池和摩尔 C：Fe 比的增加与 SOC 和大团聚体呈正相关，表明 SOC 通过物理化学保护得以保留。此外，这些变化导致微生物生物量 C 和细菌多样性随着茶园的多年而减少。A 型策略师（即酸杆菌门、放线菌门、绿弯菌门）的相对丰度同时增加，Y 型策略师的趋势相反，这表明茶园诱导的环境变化使 Y 型策略师转向 A 型策略师的优势。 总的来说，这些发现为氧化铁和微生物生活史特征在 SOC 积累和稳定中的作用提供了新的见解，包括（i） 通过络合形成 Fe-OC 对 SOC 的物理化学保护;（ii） 调节微生物群落的多样性和组成，尤其是细菌生命策略。这些结果对于更好地预测和准确控制茶园 OC 池对未来变化和干扰的响应以及维持区域 C 平衡具有重要意义。