Mineral Association and Microbial Processing Jointly Prolong Carbon Turnover in Coastal Wetlands

作者：Yong Li, Chuancheng Fu, Peng Ren, Zhaoliang Song, Lingfang Ni, Ting Wang, Changxun Yu, Jianzhong Chen, Laodong Guo, Iain P. Hartley, Ding He, Xiaoguang Ouyang, Wei Zhi, Shaopan Xia, Weiqi Wang, Mingliang Zhao, Guangxuan Han, Yongming Luo · 发表于：Global Change Biology · 年份：2026 · DOI：10.1111/gcb.70763 · 被引用次数：12 · 研究领域：Coastal wetland ecosystem dynamics、Soil Carbon and Nitrogen Dynamics、Peatlands and Wetlands Ecology

Coastal margins are critical sites for carbon (C) sequestration, yet the mechanisms stabilizing preaged, allochthonous C (externally-derived biospheric C) in these environments remain poorly understood. Specifically, the interplay between mineral association and microbial processing represents a significant knowledge gap. Here, we investigated C sequestration mechanisms in Chinese mangrove and saltmarsh soils by analyzing topsoils and cores across 36 sites spanning a 20-degree latitudinal transect. We found that saltmarshes, characterized by high mineral accretion and lower relative autochthonous C accumulation, exhibited significantly longer soil organic C (SOC) turnover times than mangroves (topsoils: ~2200 vs. ~500 years, respectively). This difference corresponded to higher proportions of preaged (~50%) and petrogenic (rock-derived; ~20%) SOC in saltmarshes. Linear mixed-effects models (LMM) confirmed that proxies for mineral protection (e.g., Al/Si) and advanced decomposition (lignin oxidation) were robust, positive predictors of turnover time across the latitudinal gradient. Further structural equation modeling (SEM) indicated a depth-dependent shift in drivers. In surface soils, microbial necromass accumulation was a significant predictor of C turnover (coefficient = 0.36). However, at depth (1 m), the degree of lignin degradation emerged as the primary predictor of multi-millennial C persistence (coefficient = 0.45). These results suggest a joint regulation mechanism ...