Divergent accumulations of microbial-derived carbon and iron-bound organic carbon in mangrove soil organic matter fractions along a salinity gradient

IF 5.7 1区农林科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY

Catena Pub Date : 2025-09-19 DOI:10.1016/j.catena.2025.109457

Chun Liu , Liqiong Li , Chunhuan He , Gan Zhang , Xule Liu , Chengxi Liu , Yuhao Zhang , Ping Li , Yuheng Zhang , Lisha Zhang

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引用次数: 0

Abstract

Despite increasing recognition of mangrove ecosystems for their importance in mitigating climate change, the underlying mechanisms of mineral preservation and microbial necromass production for soil organic matter (SOM) sequestration in estuarine mangrove ecosystems remain poorly understood. Here, we fractionated the bulk SOM into particulate organic matter (POM) and mineral-associated organic matter (MAOM) in mangrove soils and then analyzed the POM and MAOM fractions in tandem with soil mineral and microbial attributes along a salinity gradient. Our results showed that the POM proportion and soil organic carbon (SOC) content in bulk SOM decreased with increasing salinity, accompanied by increasing the contributions of microbial-derived carbon (MNC) and iron-bound OC (Fe-OC) to bulk SOC pool. Moreover, the MNC’s contribution to SOC increased in POM but decreased in MAOM with salinity, accompanied by a reduction in MNC contents in both POM and MAOM fractions. The contribution of Fe-OC in MAOM was similar to bulk SOM, accompanied by an increase in Fe-OC content as salinity increased. The bulk MNC accumulation was regulated by soil properties (total nitrogen, iron oxide (Fe_p), and pH), whereas the bulk Fe-OC accumulation was controlled by microbial attributes (MNC, microbial biomass) and Fe_p. Notably, MNC rather than Fe-OC was strongly related to SOC, and the fungal necromass was greater than the bacterial necromass, suggesting that the microbial necromass production was a key process in governing mangrove SOC accumulation by increasing fungal necromass abundance in POM pool. Our findings highlight the role of mineral preservation and microbial necromass production in the carbon sequestration of mangrove SOM in estuarine ecosystems under the influence of salinity.

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红树林土壤有机质组分中微生物衍生碳和铁结合有机碳沿盐度梯度的不同累积

尽管人们越来越认识到红树林生态系统在减缓气候变化方面的重要性，但对河口红树林生态系统中矿物保存和微生物坏死体产生土壤有机质（SOM）封存的潜在机制仍然知之甚少。本研究将红树林土壤中的有机质分成颗粒有机质（POM）和矿物伴生有机质（MAOM），并沿盐度梯度分析了POM和MAOM组分与土壤矿物和微生物属性的关系。结果表明：随着盐度的增加，土壤有机质（POM）比例和土壤有机碳（SOC）含量降低，微生物衍生碳（MNC）和铁结合OC （Fe-OC）对土壤有机碳库的贡献增加；此外，随着盐度的增加，POM组分中MNC对有机碳的贡献增加，而MAOM组分中MNC的贡献减少，POM组分和MAOM组分中MNC的含量都减少。Fe-OC在MAOM中的贡献与大块SOM相似，随着盐度的增加，Fe-OC含量也随之增加。土壤特性（全氮、氧化铁（Fep）和pH值）对土壤中微量元素（MNC）的积累起调控作用，而微生物特性（MNC、微生物生物量）和Fep对土壤中微量元素（Fe-OC）的积累起调控作用。值得注意的是，MNC而非Fe-OC与有机碳的相关性较强，且真菌坏死块大于细菌坏死块，表明微生物坏死块的产生是通过增加POM池真菌坏死块丰度来控制红树林有机碳积累的关键过程。我们的研究结果强调了在盐度影响下河口生态系统中红树林SOM的碳封存中矿物保存和微生物坏死团块产生的作用。

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来源期刊

Catena 环境科学-地球科学综合

CiteScore

10.50

自引率

9.70%

发文量

816

审稿时长

54 days

期刊介绍： Catena publishes papers describing original field and laboratory investigations and reviews on geoecology and landscape evolution with emphasis on interdisciplinary aspects of soil science, hydrology and geomorphology. It aims to disseminate new knowledge and foster better understanding of the physical environment, of evolutionary sequences that have resulted in past and current landscapes, and of the natural processes that are likely to determine the fate of our terrestrial environment. Papers within any one of the above topics are welcome provided they are of sufficiently wide interest and relevance.