气候暖湿化对高寒草甸土壤线虫群落的短期影响

doi:10.17520/biods.2023483

摘要/Abstract

摘要：

20世纪80年代后期青藏高原进入暖湿时期, 为探明青藏高原东缘气候暖湿化对高寒草甸土壤线虫群落的影响, 2020年5月作者在四川西北阿坝藏族羌族自治州红原县境内设置了对照(CK)、增水50% (P50)、增温2℃ (T2)、增水50%增温2℃ (P50+T2) 4种处理。2022年9月, 对各处理样地的线虫群落组成、密度、多样性和营养类群, 以及植物群落盖度、物种数、土壤理化性质进行调查。采用单因素方差分析和t-检验比较不同处理对土壤线虫群落的影响, 并用冗余分析和相关性分析探索线虫群落与土壤理化性质和植物群落特征之间的关系。结果表明: (1)与对照相比, P50处理中线虫群落密度和多样性增加, 但不显著; T2处理中螺旋属(Helicotylenchus)、类双胃属(Diplogsteroides)等37个属消失, 群落密度、类群数和Shannon多样性显著降低, 优势度显著增加; P50+T2处理中0-10 cm和10-20 cm土层的线虫密度分别显著增加和降低; (2) P50处理使0-10 cm土层的食真菌线虫、植物寄生线虫和捕食-杂食线虫密度增加, 食细菌线虫密度下降; T2处理使0-10 cm土层各营养类群密度均下降, 但植物寄生线虫和捕食-杂食线虫下降幅度大于食细菌线虫和食真菌线虫, 使食细菌线虫和食真菌线虫的相对密度增加; P50+T2处理使0-10 cm土层食真菌线虫密度显著提高, 10-20 cm土层食细菌线虫和植物寄生线虫密度显著降低; (3)线虫群落密度和多样性均与土壤湿度和植物盖度呈正相关, 与硝态氮呈负相关。以上研究结果表明, 不同类群线虫对水热变化的响应存在差异, 增温对高寒草甸表层土壤线虫群落密度和多样性不利, 而增水及水热同步增加有利于提高线虫群落密度。

关键词: 增温, 增水, 土壤线虫, 多样性, 营养类群, 高寒草甸

Abstract

Aim: Since the late 1980s, the climate on the Qinghai-Tibetan Plateau has become warm and humid. Soil nematodes are highly sensitive to environmental changes and used broadly as bioindicators to reflect habitat change. The aim of this study is to assess the effects of climate warming and increased precipitation on the structure and ecological dynamics of soil food webs in alpine meadows situated on the eastern edge of the Qinghai-Tibetan Plateau.

Method: Four distinct treatments were implemented in an alpine meadow located in Northwest Sichuan in May 2020. These modifications involved increasing precipitation by 50% (P50), increasing local temperature by 2℃ (T2), increasing both precipitation by 50% and local temperature by 2℃ (P50+T2), or a natural alpine meadow with no environmental alteration (CK). The investigations were conducted on taxonomic composition, density, diversity and trophic groups of soil nematode communities, coverage and species richness of plant communities, and soil properties in the plots of each treatment in September 2022. Different treatment effects on the soil nematode communities were analysed by One-way ANOVA and t-test, and the redundancy analysis and correlation analysis were employed to explore the relationships between nematode communities and soil properties as well as the characteristics of plant communities.

Results: The findings revealed: (1) The density and diversity of nematode communities treated with P50 showed an increasing trend. A total of 37 genera of nematodes, including Helicotylenchus and Diplogsteroides, were eradicated from T2 treatment. This led to a significant decrease in the density, taxonomic richness and Shannon diversity of the local soil nematode community while showing a significant increase in the Simpson dominance index. The density of nematode communities increased significantly in the 0-10 cm soil layer and decreased significantly in the 10-20 cm layer of P50+T2 treatment. (2) The density of fungivores, plant-parasites and predators-omnivores was increased in the 0-10 cm soil layer of P50 treatment but was reduced for bacterivores. In the T2 treatment, the density of each trophic group nematodes in 0-10 cm soil layer was decreased. Additionally, the restrain effect of warming was weaker on the bacterivores and fungivores compared to the plant parasites and predators-omnivores, which resulted in an overall increased relative density (or individual percentage) of bacterivores and fungivores. Notably, the P50+T2 treatment significantly elevated the density of fungivores in the 0-10 cm layer and reduced the density of bacterivores and plant-parasites in the 10-20 cm layer. (3) The density and diversity of nematode communities were positively correlated with soil moisture and plant coverage, and were negatively correlated with the content of nitrate nitrogen.

Conclusion: This study underscores the varied responses of soil nematodes to precipitation and temperature fluctuations, with the density and diversity of soil nematode communities in the topsoil layer being suppressed by two-year warming but promoted by the increased precipitation, or simultaneous increments of precipitation and temperature.

Key words: warming, increase precipitation, soil nematodes, diversity, trophic groups, alpine meadow

姚祝, 魏雪, 马金豪, 任晓, 王玉英, 胡雷, 吴鹏飞 (2024) 气候暖湿化对高寒草甸土壤线虫群落的短期影响. 生物多样性, 32, 23483. DOI: 10.17520/biods.2023483.

Zhu Yao, Xue Wei, Jinhao Ma, Xiao Ren, Yuying Wang, Lei Hu, Pengfei Wu (2024) Short-term effects of warming and wetting on the soil nematode communities in the alpine meadow. Biodiversity Science, 32, 23483. DOI: 10.17520/biods.2023483.

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链接本文: https://www.biodiversity-science.net/CN/10.17520/biods.2023483

https://www.biodiversity-science.net/CN/Y2024/V32/I5/23483

图/表 8

图1 高寒草甸水温协同变化样地设置。CK: 对照; P50: 增水50%; T2: 增温2℃; P50+T2: 增水50%增温2℃。

Fig. 1 Sample plots with changes of wetting, warming, and interaction of wetting and warming in the alpine meadow. CK, No environmental alteration; P50, Precipitation increased by 50%; T2, Temperature increased by 2℃; P50+T2, Precipitation increased by 50% and temperature increased by 2℃.

图2 不同处理0-10 cm土层(a)和10-20 cm土层(b)土壤线虫群落主成分分析。CK: 对照; P50: 增水50%; T2: 增温2℃; P50+T2: 增水50%增温2℃。

Fig. 2 Principal component analysis on soil nematode communities in different treatments of 0-10 cm (a) and 10-20 cm (b) soil layers. CK, No environmental alteration; P50, Precipitation increased by 50%; T2, Temperature increased by 2℃; P50+T2, Precipitation increased by 50% and temperature increased by 2℃.

图3 不同处理土壤线虫群落密度及多样性指数(平均值 ± 标准误)。CK: 对照; P50: 增水50%; T2: 增温2℃; P50+T2: 增水50%增温2℃。不同大写字母表示0-10 cm和10-20 cm土层间差异显著(P < 0.05), 不同小写字母表示同一土层内不同处理间差异显著(P < 0.05)。*P < 0.05; **P < 0.01; ***P < 0.001。F值和T值分别为单因素方差分析和t-检验结果。

Fig. 3 Density and diversity indices of soil nematode communities under different treatments (mean ± SE). CK, No environmental alteration; P50, Precipitation increased by 50%; T2, Temperature increased by 2℃; P50+T2, Precipitation increased by 50% and temperature increased by 2℃. Different capital letters indicate significant difference between 0-10 cm and 10-20 cm soil layers (P < 0.05), and different lowercase letters indicate significant difference between treatments within the same soil layer (P < 0.05). *P < 0.05; **P < 0.01; ***P < 0.001. The F-value and T-value are the statistical test values of one-way ANOVA and t-test, respectively.

图4 不同处理土壤线虫群落各营养类群密度(平均值 ± 标准误)。CK: 对照; P50: 增水50%; T2: 增温2℃; P50+T2: 增水50%增温2℃。Ba: 食细菌线虫; Fu: 食真菌线虫; Pl: 植物寄生线虫; Pr: 捕食-杂食线虫。不同大写字母表示0-10 cm和10- 20 cm土层间差异显著(P < 0.05), 不同小写字母表示同一土层内不同处理间差异显著(P < 0.05)。

Fig. 4 Density of soil nematode trophic groups in different treatments (mean ± SE). CK, No environmental alteration; P50, Precipitation increased by 50%; T2, Temperature increased by 2℃; P50+T2, Precipitation increased by 50% and temperature increased by 2℃. Ba, Bacterivores; Fu, Fungivores; Pl, Plant-parasites; Pr, Predators-omnivores. Different capital letters indicate significant difference between 0-10 cm and 10-20 cm soil layers (P < 0.05), and different lowercase letters indicate significant difference between treatments within the same soil layer (P < 0.05).

图5 不同处理土壤线虫群落营养类群相对密度(平均值 ± 标准误)。CK: 对照; P50: 增水50%; T2: 增温2℃; P50+T2: 增水50%增温2℃。Ba: 食细菌线虫; Fu: 食真菌线虫; Pl: 植物寄生线虫; Pr: 捕食-杂食线虫。图5a中, 不同大写字母表示0-10 cm和10-20 cm土层之间差异显著(P < 0.05), 不同小写字母表示同一土层内各处理之间差异显著(P < 0.05)。图5b中, 不同小写字母表示同一土层内不同营养类群之间差异显著(P < 0.05)。

Fig. 5 Relative density of soil nematode trophic groups in different treatments (mean ± SE). CK, No environmental alteration; P50, Precipitation increased by 50%; T2, Temperature increased by 2℃; P50+T2, Precipitation increased by 50% and temperature increased by 2℃. Ba, Bacterivores; Fu, Fungivores; Pl, Plant-parasites; Pr, Predators-omnivores. In Figure 5a, Different capital letters indicate significant differences between 0-10 cm and 10-20 cm soil layers (P < 0.05), and different lowercase letters indicate significant differences between treatments within the same soil layer (P < 0.05). In Figure 5b, different lowercase letters indicate significant differences among trophic groups within the same soil layer (P < 0.05).

图6 不同处理的土壤线虫群落生态指数(平均值 ± 标准误)。CK: 对照; P50: 增水50%; T2: 增温2℃; P50+T2: 增水50%增温2℃。不同大写字母表示0-10 cm和10-20 cm土层间差异显著(P < 0.05), 不同小写字母表示同一土层内不同处理间差异显著(P < 0.05)。

Fig. 6 Ecological indices of soil nematode communities in different treatments (mean ± SE). CK, No environmental alteration; P50, Precipitation increased by 50%; T2, Temperature increased by 2℃; P50+T2, Precipitation increased by 50% and temperature increased by 2℃. Different capital letters indicate significant differences between soil 0-10 cm and 10-20 cm soil layers (P < 0.05), and different lowercase letters indicate significant differences between treatments within the same soil layer (P < 0.05).

图7 0-10 cm土层(a)和10-20 cm土层(b)线虫群落与环境因子的冗余分析(RDA)。CK: 对照; P50: 增水50%; T2: 增温2℃; P50+T2: 增水50%增温2℃。SM: 湿度; TN: 全氮; AN: 铵态氮; NN: 硝态氮; SOC: 土壤有机碳; PB: 植物生物量; PC: 植物盖度; PR: 植物丰富度。

Fig. 7 Redundancy analysis (RDA) on the relationship between soil nematode communities and environmental factors in 0-10 cm (a) and 10-20 cm (b) soil layers. CK, No environmental alteration; P50, Precipitation increased by 50%; T2, Temperature increased by 2℃; P50+T2, Precipitation increased by 50% and temperature increased by 2℃. SM, Soil moisture; TN, Total nitrogen; AN, Ammonium nitrogen; NN, Nitrate nitrogen; SOC, Soil organic carbon; PB, Plant biomass; PC, Plant coverage; PR, Plant richness.

图8 土壤线虫与环境因子间的相关性分析。SM: 湿度; TN: 全氮; AN: 铵态氮; NN: 硝态氮; SOC: 土壤有机碳; PB: 植物生物量; PC: 植物盖度; PR: 植物丰富度。DE: 密度; TR: 丰富度; H: Shannon多样性指数; C: Simpson优势度指数。Ba: 食细菌线虫密度; Fu: 食真菌线虫密度; Pl: 植物寄生线虫密度; Pr: 捕食-杂食线虫密度。EI: 富集指数; SI: 结构指数; CI: 通道指数; BI: 基础指数; MI: 成熟度指数; WI: 瓦斯乐斯卡指数。图片中红色表示正相关, 蓝色表示负相关, 颜色越深表示相关系数越大。*P < 0.05; **P < 0.01; ***P < 0.001。

Fig. 8 Correlation analysis on the relationships between soil nematodes and environmental factors. SM, Soil moisture; TN, Total nitrogen; AN, Ammonium nitrogen; NN, Nitrate nitrogen; SOC, Soil organic carbon; PB, Plant biomass; PC, Plant coverage; PR, Plant richness. DE, Density; TR, Taxonomic richness; H, Shannon diversity index; C, Simpson dominance index. Ba, Bacterivore density; Fu, Fungivore density; Pl, Plant-parasite density; Pr, Predator-omnivore density. EI, Enrichment index; SI, Structure index; CI, Channel index; BI, Basal index; MI, Maturity index; WI, Wasilewska index. Red indicates positive correlation, blue indicates negative correlation, the darker the color, the greater the correlation coefficient. *P < 0.05; **P < 0.01; ***P < 0.001.

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