Abstract

In mountains, current land-use changes are altering plant communities of semi-natural grasslands with potential cascading effects on associated herbivores. Besides vegetation changes, temperature is also a key driver of insect diversity, and in the European Alps is predicted to increase by 0.25 °C per decade. Understanding herbivore responses to temperature and plant composition changes in mountain environments is of increasing importance. Our study aims at investigating the response to temperature and plant diversity and composition of two key herbivore groups (orthopterans and leafhoppers) belonging to contrasting feeding guilds (chewers vs. sap-feeders). We hypothesized that orthopteran diversity would be driven by temperature while leafhoppers by plant community composition. We selected 15 dry calcareous grasslands ranging from 100 to 1330 m a.s.l. along two independent gradients of plant diversity and temperature. We sampled orthopteran and leafhopper species richness and abundance by sweep-netting. Consistent with their low feeding specialisation, orthopteran species richness and community composition were only driven by temperature. By contrast, leafhopper species richness was not affected by temperature nor by plant diversity but leafhopper community composition was strongly influenced by plant species composition. This response can be explained by the higher host feeding specialisation of many leafhopper species. Species rarity and mobility did not change the response of the diversity of both groups, but orthopteran abundance increased with temperature only for highly mobile species. Altogether, our results suggest that future responses of grassland herbivores to vegetation changes and temperature warming are highly variable and depend on the feeding strategy and specialisation of the focal herbivore group.

Implications for insect conservation

Leafhoppers emerged to be particularly sensitive to potential management or climate-induced change in vegetation composition, while orthopterans are expected to respond directly to temperature warming due to their relaxed association with plant community diversity and composition.

中文翻译：

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温度和植物多样性对石灰性干旱草原直翅目和叶蝉的影响

摘要

在山区，当前的土地利用变化正在改变半天然草原的植物群落，对相关的草食动物具有潜在的连锁效应。除了植被变化外，温度还是昆虫多样性的关键驱动力，在欧洲阿尔卑斯山，预计每十年会升高0.25°C。了解草食动物对山区环境中温度和植物组成变化的反应越来越重要。我们的研究旨在调查温度和植物多样性以及两个主要食草动物群体（直翅目和叶蝉）的组成对的反应，它们属于不同的喂养行会（chewers。sap-feeder）。我们假设直翅目昆虫的多样性将由温度驱动，而叶蝉则由植物群落组成。我们选择了15个钙质干燥草原，面积从100到1330 m a。沿植物多样性和温度的两个独立梯度变化。我们通过扫网对直翅目和叶蝉的物种丰富度和丰度进行了采样。与低摄食专长一致，直翅目物种的丰富性和群落组成仅受温度驱动。相比之下，叶蝉物种的丰富度不受温度或植物多样性的影响，但叶蝉群落组成受植物物种组成的强烈影响。这种反应可以通过许多叶蝉种类的更高的寄主食性来解释。物种的稀有性和流动性并没有改变两组物种多样性的响应，但是直翅目昆虫的丰度仅随高度活动的物种而增加。共，

对昆虫保护的意义

叶蝉似乎对潜在的管理或气候导致的植被组成变化特别敏感，而直翅目昆虫由于与植物群落的多样性和组成的松散联系而有望直接对温度升高做出反应。