地上植物资源向地下部输入被认为是调控土壤生物群落的关键因素, 因为植物是几乎所有土壤生物的主要能量来源。然而, 关于植物凋落物特性和多样性如何影响土壤微生物和微型动物的多样性和群落仍然知之甚少。本研究以土壤细菌和线虫为研究对象, 通过盆钵试验, 设置单一添加不同热带森林优势植物种凋落物, 以及构建不同种凋落物混合的多样性梯度(1种、2种、4种和7种), 探究不同植物凋落物本身特性及多样性对土壤细菌和线虫群落的影响。结果显示: (1)凋落物添加显著提高了土壤碳、氮、有效磷、有效钾含量, 并显著增加了土壤pH值。(2)与对照处理(不添加凋落物)相比, 添加单一植物种凋落物降低了细菌和线虫多样性。(3)与对照处理相比, 单独添加不同植物种的凋落物对细菌和线虫群落均有显著影响。然而在不同凋落物添加处理之间, 只有望天树凋落物处理与其他处理间细菌群落具有显著差异, 其余处理间细菌和线虫群落差异均不显著。(4)凋落物多样性会显著影响细菌和线虫多样性及群落组成, 具体表现为细菌和线虫多样性随凋落物多样性梯度增加而增加。相较于低的凋落物多样性处理(CK、1种、2种), 高多样性条件下(4种和7种)细菌和线虫群落相似度更低。上述研究结果表明地上凋落物多样性不仅会直接影响土壤微生物群落, 还将通过级联效应影响更高营养级别的土壤动物群落。研究结果对于深入理解植物与细菌和线虫多样性及群落的关系、热带森林中土壤养分斑块的聚集效应、生物多样性的维持机制, 以及全球变化背景下植物多样性丧失对土壤生态系统的潜在影响等方面都提供了重要的理论参考价值。

Aims: The input of aboveground plant resources into the belowground components is considered a key factor in regulating soil biota communities, as plants serve as the primary energy source for nearly all soil organisms. However, our understanding of how plant litter identity and diversity influence the diversity and communities of soil microorganisms and microfauna remains limited. Therefore, the objective of this study is to investigate the impact of different plant litter identity and diversity on soil bacterial and nematode diversity and communities.

Methods: In this study, soil bacteria and nematodes were selected as the subjects of investigation. Through pot experiments, we first introduced litter from various dominant tropical forest plant species individually, aiming to explore the influence of distinct plant litter identity on the diversity and communities of soil bacteria and nematodes. Subsequently, we established five gradients of litter diversity, including a control (with no added litter), one-species litter (from Sloanea tomentosa), two-species mixed litter (Sloanea tomentosa + Strychnos cathayensis), four-species mixed litter (Sloanea tomentosa + Strychnos cathayensis + Orophea laui + Pometia pinnata), and seven-species mixed litter (Sloanea tomentosa + Strychnos cathayensis + Orophea laui + Pometia pinnata + Ficus virens + Ficus sagittata + Castanopsis indica). The aim was to investigate the impact of varying plant litter diversity on the diversity and communities of soil bacteria and nematodes.

Results: Our results revealed the following: (1) Litter addition significantly increased soil carbon, nitrogen, available phosphorus, available potassium content, and notably raised soil pH. (2) Compared to the control treatment (no litter addition), adding litter from a single plant species led to a decrease in bacterial and nematode diversity. (3) Similarly, adding litter from different individual plant species had significant impacts on both bacterial and nematode communities compared to the control treatment. However, among the various litter addition treatments, only the litter from the Parashorea chinensis significantly differed in bacterial community composition from the other treatments, while differences in bacterial and nematode communities between other treatments were not significant. (4) Litter diversity significantly influenced bacterial and nematode diversity and community composition. Specifically, bacterial and nematode diversity increased with higher litter diversity gradients. Under high diversity conditions (four and seven species), bacterial and nematode communities showed less similarity compared to treatments with lower litter diversity (CK, one, and two species).

Conclusion: These findings suggest that aboveground litter diversity not only directly affects the soil microbial communities, but also influences soil faunal communities at higher trophic levels through cascading effects. The results provide important theoretical references for understanding the relationship between plant and bacterial and nematode diversity and communities, the aggregation effect of soil nutrient patches in tropical forests, the mechanism of biodiversity maintenance, and the potential impacts of the loss of plant diversity on soil ecosystems in the context of global change.