{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,2]],"date-time":"2026-08-02T04:47:28Z","timestamp":1785646048471,"version":"3.56.0"},"reference-count":53,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2026,7,31]],"date-time":"2026-07-31T00:00:00Z","timestamp":1785456000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Guangdong Basic Applied Basic Research Foundation","award":["2024A1515012395"],"award-info":[{"award-number":["2024A1515012395"]}]},{"name":"Guangxi Forestry Science and Technology Project","award":["2025GXZCLK14"],"award-info":[{"award-number":["2025GXZCLK14"]}]},{"name":"National College Students\u2019 Innovation and Entrepreneurship Training Program","award":["202510593026"],"award-info":[{"award-number":["202510593026"]}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"crossref","award":["32201549"],"award-info":[{"award-number":["32201549"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"crossref"}]},{"award":["32201549"],"award-info":[{"award-number":["32201549"]}],"id":[{"id":"https:\/\/ror.org\/01h0zpd94","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Plants"],"abstract":"<jats:p>Introducing nitrogen (N)-fixing trees into plantations is a promising strategy to increase soil organic carbon (SOC) storage. However, whether this practice enhances SOC stability, a key determinant of long-term carbon sequestration, and through which specific microbial pathways, remains poorly understood. Here, we compared pure Eucalyptus plantations with mixed plantations containing the N-fixing tree Erythrophleum fordii (E. fordii) in subtropical China by measuring SOC fractions, microbial communities, extracellular enzymes, and microbial-derived carbon (MNC) content. After five years of plantation establishment, mixed plantations significantly increased total SOC by 22.41% compared to pure eucalypt stands. More importantly, this increase was accompanied by a pronounced shift in the carbon pool toward more stable mineral-associated organic carbon (MAOC), which increased by 28.39% in the surface layer. This increase was associated with microbial community restructuring characterized by a greater fungal contribution. The fungal-derived carbon (FNC) rose by 51.20%, and structural equation modeling showed that MNC contributed directly to MAOC formation, a stronger effect than the indirect enzyme-mediated pathway. Our findings provide field-based evidence that mixing Eucalyptus with N-fixing trees enhances SOC stability, primarily through the association between FNC accumulation and MAOC formation. This microbial mechanism provides a process-based perspective for evaluating mixed-species N-fixing tree plantations as a carbon-friendly management strategy in subtropical forestry.<\/jats:p>","DOI":"10.3390\/plants15152367","type":"journal-article","created":{"date-parts":[[2026,7,31]],"date-time":"2026-07-31T15:02:01Z","timestamp":1785510121000},"page":"2367","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Nitrogen-Fixing Trees Shift Soil Organic Carbon Toward Mineral-Associated Stability by Enhancing Microbial-Derived Carbon in Subtropical Plantations"],"prefix":"10.3390","volume":"15","author":[{"given":"Hongwei","family":"Bai","sequence":"first","affiliation":[{"name":"Guangxi Colleges and Universities Key Laboratory for Cultivation and Utilization of Subtropical Forest Plantation, School of Forestry, Guangxi University, Nanning 530004, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yinying","family":"He","sequence":"additional","affiliation":[{"name":"Guangxi Colleges and Universities Key Laboratory for Cultivation and Utilization of Subtropical Forest Plantation, School of Forestry, Guangxi University, Nanning 530004, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qing","family":"Liu","sequence":"additional","affiliation":[{"name":"Guangxi Colleges and Universities Key Laboratory for Cultivation and Utilization of Subtropical Forest Plantation, School of Forestry, Guangxi University, Nanning 530004, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Junhao","family":"Chen","sequence":"additional","affiliation":[{"name":"Guangxi Colleges and Universities Key Laboratory for Cultivation and Utilization of Subtropical Forest Plantation, School of Forestry, Guangxi University, Nanning 530004, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wending","family":"Tan","sequence":"additional","affiliation":[{"name":"Guangxi Colleges and Universities Key Laboratory for Cultivation and Utilization of Subtropical Forest Plantation, School of Forestry, Guangxi University, Nanning 530004, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mei","family":"Yang","sequence":"additional","affiliation":[{"name":"Guangxi Colleges and Universities Key Laboratory for Cultivation and Utilization of Subtropical Forest Plantation, School of Forestry, Guangxi University, Nanning 530004, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8825-6702","authenticated-orcid":false,"given":"Xianyu","family":"Yao","sequence":"additional","affiliation":[{"name":"Guangxi Colleges and Universities Key Laboratory for Cultivation and Utilization of Subtropical Forest Plantation, School of Forestry, Guangxi University, Nanning 530004, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,31]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"847","DOI":"10.1038\/s41558-022-01432-3","article-title":"Biophysical and economic constraints on China\u2019s natural climate solutions","volume":"12","author":"Lu","year":"2022","journal-title":"Nat. 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