青藏高原高寒草甸土壤环境对线虫功能多样性的影响

doi:10.17520/biods.2020042

摘要/Abstract

摘要：

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。

关键词: 高寒草甸, 土壤线虫, 土壤环境, 功能多样性, 物种多样性, 土壤总磷

Abstract

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.

Key words: alpine meadow, soil nematodes, soil environment, functional diversity, taxonomic diversity, soil phosphorus

王宇彤, 牛克昌 (2020) 青藏高原高寒草甸土壤环境对线虫功能多样性的影响. 生物多样性, 28, 707-717. DOI: 10.17520/biods.2020042.

Yutong Wang, Kechang Niu (2020) Effect of soil environment on functional diversity of soil nematodes in Tibetan alpine meadows. Biodiversity Science, 28, 707-717. DOI: 10.17520/biods.2020042.

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链接本文: https://www.biodiversity-science.net/CN/10.17520/biods.2020042

https://www.biodiversity-science.net/CN/Y2020/V28/I6/707

图/表 4

表1 广义线性混合效应模型检验不同研究点和生境对土壤线虫多样性的影响

Table 1 Summary of site and terrain effect on variation in soil nematode diversity tested by generalized linear mixed effect model

	变异度 Variability (%)		以研究点A为参照的研究点间差异 Direction and strength of site effect (relative to site A)		以沟底平地为参照的生境间差异 Direction and strength of terrain effect (relative to plots at valleys)
	研究点 Sites	生境 Terrain	B研究点 Site B	C研究点 Site C	阴坡 Northern	阳坡 Southern	山顶 Top
线虫α多样性 Nematode α diversity
线虫丰富度 Nematode richness	2.44	23.3	0.07	0.13	0.09	0.27^*	-0.14
线虫Shannon多样性 Nematode Shannon diversity	8.67	39.36^*	0.07	0.24^*	0.06	0.46^*	-0.05
线虫均匀度 Nematode evenness diversity	8.59	25.02^*	-0.02	0.03	0.02	0.09^*	0.05
线虫个体多度 Nematode individual abundance	2.77	25.39^*	17.51^*	3.65	-1.27	18.47^*	-45.83^*
基于个体大小的土壤线虫功能多样性 Body-size based functional diversity of soil nematodes
群落水平个体大小 CWM for body-size	9.44	7.19	-4.25	1.89	2.83	0.80	5.96
个体大小多样性 FD_Rao for body-size	8.6	9.5	-2.03	2.5	0.38	1.53	5.18
不同线虫功能类群个体多度 Individual abundance of each functional group
食细菌线虫 Bacterivores	22.22^*	15.0	0.85^*	0.86^*	-0.41^*	-0.46^*	-0.68^*
食真菌线虫 Fungivores	2.19	6.43	0.01	-0.15	-0.04	-0.20^*	-0.26^*
植食线虫 Herbivores	6.45	3.42	0.44^*	0.01	0.44^*	0.13	0.24
捕食杂食线虫 Omnivores-Predators	3.38	20.03	-0.32^*	-0.06	0.86^*	0.71^*	0.19
植物物种丰富度 Plant species richness	5.60	45.93^*	0.09	0.08	-0.15	-0.25^*	-0.25^*
土壤理化因子 Edaphic factors
土壤pH值 Soil pH	3.17^*	89.6^*	0.21^*	0.13^*	0.26^*	1.17^*	0.15^*
土壤有机质 Soil organic matter	0.23	34.8^*	2.51	1.61	-25.6^*	3.05	7.53
土壤总磷 Soil total P	2.63	50.5^*	-0.01	-0.37	-0.46	-1.86^*	-1.53
土壤速效磷 Soil available P	10.3^*	70.2^*	1.19^*	1.77^*	-2.42^*	-2.95^*	-5.42^*
土壤总氮 Soil total N	17.7^*	38.9^*	0.42^*	0.48^*	-0.02	-0.50^*	-0.74^*
土壤速效氮 Soil available N	14.6^*	79.1^*	7.3	36.9	60.4	-26.1^*	-34.7

表1 广义线性混合效应模型检验不同研究点和生境对土壤线虫多样性的影响

Table 1 Summary of site and terrain effect on variation in soil nematode diversity tested by generalized linear mixed effect model

	变异度 Variability (%)		以研究点A为参照的研究点间差异 Direction and strength of site effect (relative to site A)		以沟底平地为参照的生境间差异 Direction and strength of terrain effect (relative to plots at valleys)
	研究点 Sites	生境 Terrain	B研究点 Site B	C研究点 Site C	阴坡 Northern	阳坡 Southern	山顶 Top
线虫α多样性 Nematode α diversity
线虫丰富度 Nematode richness	2.44	23.3	0.07	0.13	0.09	0.27^*	-0.14
线虫Shannon多样性 Nematode Shannon diversity	8.67	39.36^*	0.07	0.24^*	0.06	0.46^*	-0.05
线虫均匀度 Nematode evenness diversity	8.59	25.02^*	-0.02	0.03	0.02	0.09^*	0.05
线虫个体多度 Nematode individual abundance	2.77	25.39^*	17.51^*	3.65	-1.27	18.47^*	-45.83^*
基于个体大小的土壤线虫功能多样性 Body-size based functional diversity of soil nematodes
群落水平个体大小 CWM for body-size	9.44	7.19	-4.25	1.89	2.83	0.80	5.96
个体大小多样性 FD_Rao for body-size	8.6	9.5	-2.03	2.5	0.38	1.53	5.18
不同线虫功能类群个体多度 Individual abundance of each functional group
食细菌线虫 Bacterivores	22.22^*	15.0	0.85^*	0.86^*	-0.41^*	-0.46^*	-0.68^*
食真菌线虫 Fungivores	2.19	6.43	0.01	-0.15	-0.04	-0.20^*	-0.26^*
植食线虫 Herbivores	6.45	3.42	0.44^*	0.01	0.44^*	0.13	0.24
捕食杂食线虫 Omnivores-Predators	3.38	20.03	-0.32^*	-0.06	0.86^*	0.71^*	0.19
植物物种丰富度 Plant species richness	5.60	45.93^*	0.09	0.08	-0.15	-0.25^*	-0.25^*
土壤理化因子 Edaphic factors
土壤pH值 Soil pH	3.17^*	89.6^*	0.21^*	0.13^*	0.26^*	1.17^*	0.15^*
土壤有机质 Soil organic matter	0.23	34.8^*	2.51	1.61	-25.6^*	3.05	7.53
土壤总磷 Soil total P	2.63	50.5^*	-0.01	-0.37	-0.46	-1.86^*	-1.53
土壤速效磷 Soil available P	10.3^*	70.2^*	1.19^*	1.77^*	-2.42^*	-2.95^*	-5.42^*
土壤总氮 Soil total N	17.7^*	38.9^*	0.42^*	0.48^*	-0.02	-0.50^*	-0.74^*
土壤速效氮 Soil available N	14.6^*	79.1^*	7.3	36.9	60.4	-26.1^*	-34.7

图1 3个研究点的4个生境中土壤理化因子与土壤线虫多样性(a)和土壤线虫各功能群个体多度(b)的关系

Fig. 1 Relationship between edaphic factors and soil nematodes diversity (a), and individual abundance of each functional group (b) over four terrains at each of three sites. SOM, Soil organic matter; SAP, Soil available P; STN, Soil total N; SAN, Soil available N; STP, Soil total P; PSR, Plant species richness; CWM, Community-weighted mean; FDRao, Functional diversity in term of Rao index.

图2 Bayes回归估计土壤环境对土壤线虫多样性的影响。土壤理化因子和植物物种丰富度对线虫多样性的影响大小以回归分析中的斜率分布估计, 其中95%置信区间不与零重叠表示影响显著。

Fig. 2 Effect of soil environment on soil nematode diversity assessed by Bayesian regression model. The effect of edaphic factors and plant species richness on soil nematode diversity assessed by distribution of estimated slopes, with significant effects indicated by 95% credible intervals that do not overlap zero. CWM, Community-weighted mean; FDRao, Functional diversity in term of Rao index.

图3 Bayes回归估计土壤环境对土壤线虫各功能群多度的影响。土壤理化因子和植物物种丰富度对各功能群多度的影响大小以回归分析中的斜率分布估计, 其中95%置信区间不与零重叠表示影响显著。

Fig. 3 Effect of soil environment on individual abundance of each functional group of soil nematodes assessed by Bayesian regression model. The effect of edaphic factors and plant species richness on individual abundance of each functional group of soil nematodes assessed by distribution of estimated slopes, with significant effects indicated by 95% credible intervals that do not overlap zero.

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