Integrative Biology Journals

J Plant Ecol ›› 2026, Vol. 19 ›› Issue (1): rtaf160.DOI: 10.1093/jpe/rtaf160

• Research Article •    

Intraspecific underplanting enhances rhizospheric phosphorus availability in subtropical Chinese fir plantations: Implications for sustainable forest management

Ming Li1,2†, Pingping Lian3†, Xinyu Zhang1, Junjiao Ma1, Yuhui Jiang1, Yangyang Sun3, Shundan Chen1, Xia Hu1, Pengfei Wu1,2, Shuisheng Fan3*, Xiangqing Ma1,2*   

  1. 1College of Forestry, Fujian Agriculture and Forestry University, Fuzhou 350002, China, 2Chinese Fir Engineering and Technological Research Center, National Forestry and Grassland Administration, Fuzhou 350002 , China, 3College of JunCao Science and Ecology (College of Carbon Neutrality), Fujian Agriculture and Forestry University, Fuzhou 350002, China

    *Corresponding author. E-mail: shuisheng@fafu.edu.cn (S.F.); lxymxq@126.com (X.M.)

    †These authors contributed equally to this work.

  • Received:2025-07-07 Accepted:2025-09-15 Online:2025-09-30 Published:2026-02-01
  • Supported by:
    This work was financially supported by the National Natural Science Foundation of China (Grant No. 32471906) and the First-Class Discipline Construction Funding of Forestry at Fujian Agriculture and Forestry University（725025030).

种内套种提升亚热带杉木人工林根际磷有效性：对可持续森林管理的启示

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Abstract: Underplanting represents a traditional silvicultural practice, and optimal underplanting can enhance plant acquisition of limiting nutrients, especially phosphorus (P). Chinese fir (Cunninghamia lanceolata) is widely planted in low-latitude P-deficient regions. However, the beneficial companion species and species-specific rhizospheric mechanisms governing soil P availability in these systems remain poorly resolved. To address this, the study evaluated rhizospheric P cycling mechanisms in a 46-year-old plantation underplanted for 10 years with four treatments: autospecific Chinese fir (CF), Schima superba (CS), Liriodendron chinense (CL), and Manglietia fordiana (CM). After ten years, CF exhibited significantly higher available P (AP), organic P, and total P compared to broadleaf systems (CM, CS, CL), along with elevated microbial biomass P (MBP) and alkaline phosphatase (ALP) activity. Functional gene analysis reveals higher abundances of P-solubilizing (ppx, pqqC, gcd) and mineralizing (phoD, phnK, phoX) genes in CF. Root exudation profiles demonstrate that CF secreted more oxalic acid than CS and CL, and exhibited significantly higher ALP activity, which was a primary driver of organic P mineralization. These results highlight that intraspecific underplanting enhances rhizospheric P availability primarily through microbial-driven organic P mineralization, supported by organic acid-mediated solubilization of mineral-bound P. CF systems maintained higher microbial biomass and phosphatase activity while minimizing interspecific competition, unlike broadleaf treatments, where nutrient competition reduced microbial efficiency. This study proposes CF intraspecific underplanting as a sustainable strategy to alleviate P limitation during the early stages of underplantation in mature subtropical plantations via microbial-driven organic P mineralization and organic acid mediated solubilization, offering a sustainable strategy to alleviate P limitation in subtropical plantations.

In a long-term interplanting trial in subtropical Chinese fir forests, intraspecific interplanting of Chinese fir was found to effectively alleviate soil phosphorus limitation. This approach maintains higher microbial biomass and phosphatase activity, significantly promoting organic phosphorus mineralization and mineral phosphorus activation, thereby forming an efficient rhizosphere phosphorus activation mechanism. In contrast, interplanting with broadleaf species reduced microbial phosphorus conversion efficiency due to nutrient competition.

Key words: Phosphorus mobilization, rhizosphere microbial biomass, acid phosphatase activity, organic acid secretion, intraspecific underplanting

摘要：
林下套种是一种传统的森林管理模式，优化套种能增强植物对磷等限制性营养元素的获取。杉木(Cunninghamia lanceolata)广泛种植于亚热带贫磷土壤，杉木林下套种阔叶树被认为是提升土壤磷有效性的重要途径。然而，目前尚不清楚不同树种搭配如何通过根际过程调控土壤磷有效性。本研究以46年生杉木林为对象，解析了持续10年的4种林下套种模式(杉木种内套种，CF；套种木荷(Schima superba)，CS；套种鹅掌楸(Liriodendron chinense)，CL；套种木莲(Manglietia fordiana)，CM)对根际磷循环的影响机制。结果发现，CF处理的根际土壤有效磷、有机磷和全磷含量均显著高于3种阔叶树套种处理，且CF处理表现出最高的微生物生物量磷和碱性磷酸酶(ALP)活性。功能基因分析发现，CF处理中溶磷基因(ppx, pqqC, gcd)和矿化基因(phoD, phnK, phoX)丰度更高。根系分泌物测定结果显示，CF处理分泌的草酸量高于CS和CL，且ALP活性更强，是有机磷矿化的主要驱动因素。上述结果表明，杉木种内套种主要通过微生物驱动的有机磷矿化来提升根际磷有效性，而有机酸分泌则辅助活化了矿物态磷。杉木种内套种在最小化种间竞争的同时，维持了更高的微生物生物量和磷酸酶活性，而套种阔叶树处理中养分竞争降低了微生物效率。总体而言，杉木种内套种能够通过微生物驱动的有机磷矿化和有机酸介导的溶磷作用，缓解亚热带成熟人工林林下套种早期阶段的磷限制，为森林可持续管理提供科技支撑。

关键词: 磷活化, 根际微生物生物量, 酸性磷酸酶活性, 有机酸分泌, 种内套种

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