摘要:食物网中的上行效应和下行效应对于群落的动态和生态系统功能有十分重要的影响，旨在探讨互利关系和植物多样性对节肢动物群落中食物网不同营养级之间的影响。通过随机裂区试验方法，分别设置了3种蚂蚁-紫胶虫互利关系处理（有互利关系、无互利关系和自然对照）以及3种植物多样性处理（单一种植、2树种混植和3树种混植），于2016年8月和9月分两次用手捡法、网扫法和震落法采集试验地寄主植物上所有的节肢动物，并按照不同营养级将其分类。利用结构方程模型分析方法对不同营养级之间的相互作用的路径和强度进行了比较，结果显示：1）互利关系对捕食者和消费者均有显著的下行作用，有互利关系处理下蚂蚁对捕食者的路径强度要强于自然对照组，互利关系对捕食者的影响要强于对消费者的影响。2）植物多样性会通过影响植物的生物量而对消费者和捕食者产生显著的上行效应影响，这种影响会随着营养级的升高而显著减小。3）消费者主要受植物多样性的上行效应影响，而捕食者主要受互利关系的下行效应影响。有互利关系的食物网结构更加复杂，营养级之间的相互作用更为显著。探讨了以蚂蚁-紫胶虫互利关系为核心作用的紫胶林生态系统中互利关系和植物多样性对节肢动物食物网中各营养级的影响，揭示了上行效应和下行效应对各营养级的作用途径和强度，其结果有一定的理论参考价值。



Abstract:The bottom-up and top-down effects in the food web have a significant impact on community dynamics and ecosystem functions. This study aims to explore the effects of mutualism relationships and plant diversity on different trophic levels of food webs in arthropod communities. Three levels of ant-lac insects mutualism treatments (presence, absence of mutualism, and natural control) and three kinds of plant diversity treatments (monoculture, two species planting, and three species planting) were set up by randomized split-plot experiment design. We collected all arthropods on the host plants under by using hand-collection, shake-down, and sweeping method in August and September 2016. Then we identified all arthropods on the basis of different trophic levels. Structural equation modeling was used to compare the path and intensity of the interactions among different trophic levels. The results showed that:1) Mutualism relationship had a significant top-down effect on predators and consumers. The path strength of mutualism ants to predators was stronger than that of natural control treatment. Mutualism relationship had a greater impact on predators than consumers. 2) Plant diversity had a significant bottom-up effect on consumers and predators by affecting plant biomass, and this effect was significantly reduced as the trophic level increased. 3) Consumers were mainly affected by the bottom-up effects of plant diversity, while predators were mainly affected by the top-down effects of mutualism ants. The food web structure with mutualism relationship was more complex, and the interaction between trophic levels was more significant. This study not only explored the effect of mutualism and plant diversity on different trophic levels in arthropod food webs in a lac plantation ecosystem, but also revealed the pathways and strengths of top-down and bottom-up effects to each trophic level. The results have certain theoretical reference value.





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