Aims Mangroves hold large organic carbon (C) stocks in their soils. These C stocks are mainly attributed to the high productivity and slow decomposition of the below-ground biomass. Rates of decomposition are strongly influenced by edaphic factors including soil bulk density (BD). Hence, this study assessed the influence of soil BD on mangrove root material and its effect on decomposition. Methods To determine the effect of the BD in which the plants were grown on decomposition rates (i.e. mass loss), four mangrove species were grown in soils of six different BD. The root material was then placed in litterbags and incubated in mangrove forest soil for three months. Additionally, the root material was analysed for nitrogen (N) and phosphorus (P), as well as lignin and cellulose content. Results The soil BD experienced during root growth strongly affected mass loss, which decreased with increasing soil BD of the growth media. Decomposition also differed among species. Variation in mass loss was likely influenced by N levels, C:N ratios and lignin content of the root tissue. Conclusion Variation in soil BD influences the C sequestration potential of mangroves, as BD affects the decomposability of mangrove root tissues.

中文翻译：

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红树林根的分解取决于它们生长的体积密度

目的 红树林在其土壤中拥有大量的有机碳 (C) 储量。这些碳库主要归因于地下生物量的高生产力和缓慢分解。分解速率受到土壤因素的强烈影响，包括土壤容重 (BD)。因此，本研究评估了土壤 BD 对红树林根材料的影响及其对分解的影响。方法 为了确定植物生长的 BD 对分解率（即质量损失）的影响，在 6 种不同 BD 的土壤中种植了四种红树树种。然后将根材料放入垃圾袋中，并在红树林土壤中培养三个月。此外，还分析了根材料的氮 (N) 和磷 (P)，以及木质素和纤维素含量。结果 根系生长过程中经历的土壤 BD 强烈影响质量损失，随着生长介质土壤 BD 的增加而减少。分解也因物种而异。质量损失的变化可能受氮水平、碳氮比和根组织木质素含量的影响。结论 土壤 BD 的变化影响红树林的 C 封存潜力，因为 BD 影响红树林根组织的分解能力。