青藏高原高寒草甸土壤环境对线虫功能多样性的影响

土壤线虫是地下食物网的重要组成部分, 在生态系统能量流动和物质循环中起着至关重要的作用。大量研究报道了肥力等土壤环境对土壤线虫物种多样性及各功能群多度的影响, 而我们对土壤线虫功能多样性如何响应土壤环境变化依然知之甚少。本研究以群落水平个体大小和个体大小多样性表征土壤线虫功能多样性。在青藏高原高寒草甸选择3个研究点, 调查和分析了不同生境(沟底平地、阴坡、阳坡和山顶)土壤线虫物种多样性、各功能群多度和功能多样性及其与土壤理化因子和植物多样性的关系。结果表明: (1)土壤线虫个体多度和物种多样性在阳坡最高, 随土壤pH值和土壤总磷增加而升高; 而基于个体大小的土壤线虫功能多样性主要受土壤养分影响, 随土壤总氮和有机质增加而增加, 随土壤总磷含量增加而减少; (2)食细菌和食真菌线虫多度在沟底最高, 植食与捕食杂食线虫多度在山顶最低; 除捕食杂食线虫外, 各功能群多度也主要随土壤磷增加而升高; 除食真菌线虫外, 各功能群多度随植物物种丰富度的增加而减少。本研究强调了土壤线虫物种和功能多样性受不同土壤环境因子的影响, 丰富了土壤线虫多样性研究的内容, 为理解高寒草甸土壤动物多样性形成、维持和变化提供了更广阔的 视角。

Effect of soil environment on functional diversity of soil nematodes in Tibetan alpine meadows

Soil nematodes are key components in the soil food web, playing a crucial role in the regulation of nutrient cycling and energy flow. Many studies have documented the importance of the soil environment in regulating variation in taxonomic diversity over space and time, though little is known about how soil environment influences the functional diversity of soil nematodes. We investigated soil nematode communities in alpine meadows distributed on contrasting environmental regimes (valley floor, northern slope, southern slope, and ridge top) at each of three sites on the Tibetan Plateau. We examined the association between soil environmental factors and the functional diversity of soil nematodes using the community-weighted mean of body-size (CWM) and the Rao functional diversity of body-size (FD_Rao). Our results showed that the taxonomic diversity of soil nematodes increased significantly with soil pH while the functional diversity of soil nematodes is associated with soil fertility (i.e. CWM and FD_Rao are positively correlated with soil organic matter and nitrogen content while negatively with soil total phosphorus). Results also revealed that the abundance of bacterivores and fungivores are significantly greater in valley floor plots. The abundance of herbivores and omnivore-predators are lesser at ridge top plots, with abundance of most functional groups positively correlated with soil phosphorous content, but negatively with plant species richness. Our study suggests that soil nematode taxonomic and functional diversity exhibit a decoupled response to soil environmental factors, providing new insight into our understanding of biodiversity assembly in soil animals in Tibetan alpine meadows.