Background and aims

Delving into the regulation of soil biota and function by plants provides a comprehensive understanding of ecosystem processes, offering insights into nutrient dynamics, soil food web dynamics, soil health, and the overall functioning. However, many aspects regarding the influence of plant roots, litter identity, and diversity on nematode diversity and communities, as well as the relative contributions of plant litter and roots resources to nematode diversity and community dynamics, remain poorly understood.

Methods

To address these knowledge gaps, we conducted two interconnected experiments. Firstly, we collected litter from eight different vascular plant species and performed a pot experiment to examine the effects of litter identity on nematode diversity and community composition. Subsequently, using a subset of these species, we established litter diversity gradients with five treatments: control (litter removed), 1 species, 2 species, 4 species and 6 species mixtures in a field experiment to investigate the impacts of litter diversity and rhizodeposition (which includes root abscissions and exudates) on nematode diversity and communities. Through high-throughput sequencing and sequence alignment, nematodes were identified at the family level. Based on nematode count data, sequence relative abundances were converted into absolute nematode quantities for diversity and community analyses.

Results

Our results revealed that the removal of litter led to a significant reduction in total soil organic carbon (TOC), whereas rhizodeposition significantly increased TOC and NH₄⁺ levels. Rhizodeposition and litter addition both positively influenced nematode abundance, primarily by regulating bacterial-feeding and plant-feeding nematode populations. Additionally, nematode diversity showed significant responses to rhizodeposition, litter identity, and diversity. Excluding rhizodeposition resulted in significant reductions in the diversity of all nematode trophic taxa groups, except for fungal-feeding nematodes. Furthermore, our findings indicated that plant litter identity had a distinct effect on nematode communities, with Alchornea davidii and Rhododendron simsii emerging as the most impactful plant species for shaping these distinct nematode communities. In addition, both litter diversity and rhizodeposition exerted significant effects on nematode communities. Notably, the dissimilarity in nematode communities was significantly greater between rhizodeposition and without rhizodeposition than among different litter diversity treatments, indicating rhizodeposition had a notably stronger impact than litter diversity.

Conclusions

Overall, the findings highlight the dominant role of plant roots and litter identity over litter diversity in shaping nematode communities, providing new insights into how plants sustain complex and highly diverse soil biota.

中文翻译：

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揭示凋落物特性、多样性和根际沉积对线虫群落的影响

背景和目标

深入研究植物对土壤生物群和功能的调节，可以全面了解生态系统过程，深入了解养分动态、土壤食物网动态、土壤健康和整体功能。然而，关于植物根、凋落物特性和多样性对线虫多样性和群落的影响，以及植物凋落物和根资源对线虫多样性和群落动态的相对贡献的许多方面仍然知之甚少。

方法

为了解决这些知识差距，我们进行了两项相互关联的实验。首先，我们收集了八种不同维管束植物的凋落物，并进行盆栽实验，以研究凋落物特性对线虫多样性和群落组成的影响。随后，使用这些物种的子集，我们在田间实验中建立了五种处理的凋落物多样性梯度：对照（去除凋落物）、1 个物种、2 个物种、4 个物种和 6 个物种混合物，以研究凋落物多样性和根际沉积的影响。其中包括根脱落和渗出物）对线虫多样性和群落的影响。通过高通量测序和序列比对，在线虫在科水平上得到鉴定。根据线虫计数数据，将序列相对丰度转换为绝对线虫数量，以进行多样性和群落分析。

结果

我们的结果表明，枯枝落叶的去除导致土壤总有机碳（TOC）显着减少，而根际沉积显着增加了TOC和NH ₄ ⁺水平。根际沉积和凋落物添加都对线虫丰度产生积极影响，主要是通过调节以细菌为食和以植物为食的线虫种群。此外，线虫多样性对根际沉积、同窝特征和多样性表现出显着的反应。排除根际沉积会导致所有线虫营养类群的多样性显着降低，但以真菌为食的线虫除外。此外，我们的研究结果表明，植物凋落物特性对线虫群落具有明显的影响，其中Alchornea davidii和Rhododendron simsii成为塑造这些独特线虫群落最有影响力的植物物种。此外，凋落物多样性和根际沉积对线虫群落产生显着影响。值得注意的是，根际沉积和无根际沉积之间的线虫群落差异显着大于不同凋落物多样性处理之间的差异，表明根际沉积比凋落物多样性的影响明显更强。

结论

总体而言，这些发现强调了植物根系和凋落物特性相对于凋落物多样性在塑造线虫群落方面的主导作用，为植物如何维持复杂和高度多样化的土壤生物群提供了新的见解。