生物多样性 ›› 2022, Vol. 30 ›› Issue (11): 22069.  DOI: 10.17520/biods.2022069

所属专题: 青藏高原生物多样性与生态安全

• 研究报告:植物多样性 • 上一篇    下一篇

高寒草甸植物物种丧失对草原毛虫的影响

雍青措姆, 习新强, 牛克昌()   

  1. 南京大学生命科学学院, 南京 210023
  • 收稿日期:2022-02-09 接受日期:2022-04-24 出版日期:2022-11-20 发布日期:2022-06-23
  • 通讯作者: 牛克昌
  • 作者简介: E-mail: kechangniu@nju.edu.cn
  • 基金资助:
    国家自然科学基金(32171519)

Effect of plant species loss on grassland caterpillar in alpine meadows

Yongqingcuomu , Xinqiang Xi, Kechang Niu()   

  1. School of Life Sciences, Nanjing University, Nanjing 210023
  • Received:2022-02-09 Accepted:2022-04-24 Online:2022-11-20 Published:2022-06-23
  • Contact: Kechang Niu

摘要:

植物多样性是调控食物网结构和生态系统功能最重要的生物因素, 植物多样性丧失深刻影响食草动物, 但由于小型食草动物种群数量波动明显、统计随机性较大等困难, 我们对植物多样性丧失如何影响小型食草动物依然知之甚少。基于在青藏高原高寒草甸设置的长期植物物种剔除试验, 本研究于2016-2020年7-8月连续调查了植物物种剔除各处理中草原毛虫(Gynaephora alpherakiif)的数量, 分析了植物物种及功能群丧失对草原毛虫的影响。结果表明, 虽然时空差异及统计随机性是影响草原毛虫数量变化的主要因素, 但植物物种剔除介导的群落差异对草原毛虫数量的影响依然显著: (1)在各观测时段, 优势种线叶嵩草(Kobresia capillifolia)的丧失导致群落中草原毛虫数量显著减少; 禾草类物种丧失也会减少草原毛虫数量, 但其影响仅在8月显著; (2)杂类草物种丧失通过增加群落中禾草物种多度, 可增加草原毛虫数量; 豆科物种丧失使莎草增多, 也会增加草原毛虫数量; (3)各植物功能群部分物种剔除并未显著影响草原毛虫数量。本研究证实了高寒草甸中草原毛虫数量会因优势植物嵩草和禾草的多度减少或禾草物种丧失而显著减少, 但群落总生物量、个体数和物种丰富度、豆科多度以及各功能群植物同比减少, 都对草原毛虫数量没有明显影响。这些结果说明在随机作用主导下, 植物群落中的特定功能群相对多度(而非物种多样性)变化深刻影响草原毛虫适合度, 进而影响生态系功能及服务; 未来生物多样性研究及草地虫害生物防控中应更多考虑统计随机性及植物功能多样性对小型食草动物的影响。

关键词: 物种多样性, 群落构建, 统计随机性, 重复测量, 功能群, 功能性状

Abstract

Aims: Plant diversity plays a crucial role in regulating food web dynamics and ecosystem functioning. Existing studies have documented significant impact on large herbivores and ecosystem functioning from loss in plant species diversity. Yet, little is known about effect of plant diversity loss on small herbivores and its functional consequence on food web dynamics, ecosystem functioning and ecosystem service, due to difficulty in distinguishing the role of plant diversity from larger fluctuations of small herbivore populations under the confounding effect of multiple ecological factors and demographic stochasticity.

Methods: Based on our long-term experiment of plant species removal in an alpine meadow on the Tibetan Plateau, we repeatedly measured the number of grassland caterpillar (Gynaephora alpherakiif) in each plot (i.e. density) in July and August over five years (2016-2020). We examined the effect of plant species removal on caterpillar population by associating changes in caterpillar counts with a shift in plant community attributes following plant removal and using a set of generalized linear mixed models.

Results: Plant removal induced a difference in the plant community, which significantly and consistently influenced the caterpillar counts over years and months independent of the observed variation in caterpillar counts accounted for by the difference in years and observational times within each month. Comparing the caterpillar counts in plots without removing plant species, (i) the caterpillar counts decreased in plots subjected to removal of dominant species (Kobresia capillifolia) in both July and August across five years, and increased in plots subjected to removal of forbs species in August of 2016 and 2019, and (ii) the caterpillar counts tended to increase in plots subjected to removal of legume species but only significantly in few cases, and did not significantly differ with plots subjected to removal of partial species (accounting for 20% aboveground biomass) of each functional groups. Further analysis showed that neither total aboveground biomass nor plant species richness and total individual numbers was significantly correlated with the caterpillar counts. The variation in caterpillar counts was associated positively with aboveground biomass of sedges and grasses as well as grass species richness, but negatively with the amount of forbs and legumes. The structural equation model further revealed that the removal of Kobresiaand grass species affected caterpillar counts through decreasing aboveground biomass of graminoids, but increasing graminoids following removal of forb and legume species promoted the density of caterpillars.

Conclusion: Based on field observations on the grassland caterpillar populations in plots subjected to different removal protocols, our study provides robust evidence that the decline in relative abundance of graminoids significantly reduced the fitness of caterpillars, and thus potentially impacts grassland functioning and ecosystem service. This study also suggests that future research on biodiversity effects and biological control of pests needs to pay more attention to the effects of plant functional diversity and demographic stochasticity on small herbivores.

Key words: species diversity, community assembly, demographic stochasticity, repeated measurement, functional group, functional traits