Human activities have triggered profound changes in natural landscapes, resulting in species loss and disruption of pivotal ecological interactions such as insect herbivory. This antagonistic interaction is affected by complex pathways (e.g., abundance of herbivores and predators, plant chemical defenses, and resource availability), but the knowledge regarding how forest loss and fragmentation affect insect herbivory in human‐modified tropical landscapes still remains poorly understood. In this context, we assessed multi‐pathways by which changes in landscape structure likely influence insect herbivory in 20 Atlantic forest fragments in Brazil. Using path analysis, we estimated the direct effects of forest cover and forest edge density, and the indirect effect via canopy openness, number of understory plants and phenolic compounds, on leaf damage in understory plants located in the edge and interior of forest fragments. In particular, plants located in forest edges experienced greater leaf damage than interior ones. We observed that landscape edge density exerted a positive and direct effect on leaf damage in plants sampled at the edge of forest fragments. Our findings also indicated that forest loss and increase of edge density led to an increase in the canopy opening in the forest interior, which causes a reduction in the number of understory plants and, consequently, an increase in leaf damage. In addition, we detected that phenolic compounds negatively influence leaf damage in forest interior plants. Given the increasing forest loss in tropical regions, in which forest fragments become stranded in highly deforested, edge‐dominated and degraded landscapes, our study highlights the pervasive enhancement in insect herbivory in remaining forest fragments—especially along forest edges and canopy gaps in the forest interior. As a result, increased herbivory is likely to affect forest regeneration and accelerate the ecological meltdown processes in these highly deforested and disturbed anthropogenic landscapes.

中文翻译：

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将景观结构的变化与大西洋森林遗迹森林边缘和内部的昆虫食草联系起来


人类活动引发了自然景观的深刻变化，导致物种丧失和关键的生态相互作用（如昆虫食草）的破坏。这种拮抗相互作用受复杂途径（例如，食草动物和捕食者的丰富性、植物化学防御和资源可用性）的影响，但关于森林丧失和破碎化如何影响人类改造热带景观中的昆虫食草性的认识仍然知之甚少。在此背景下，我们评估了景观结构变化可能影响巴西 20 个大西洋森林碎片中昆虫食草的多途径。使用路径分析，我们估计了森林覆盖和森林边缘密度的直接影响，以及通过树冠开放度、林下植物和酚类化合物的数量对位于森林碎片边缘和内部的林下植物叶片损伤的间接影响。特别是，位于森林边缘的植物比室内植物遭受的叶子损害更大。我们观察到景观边缘密度对在森林碎片边缘采样的植物的叶片损伤产生了积极和直接的影响。我们的研究结果还表明，森林损失和边缘密度的增加导致森林内部树冠开口的增加，这导致林下植物的数量减少，从而增加树叶损伤。此外，我们检测到酚类化合物对森林内部植物的叶片损伤产生负面影响。 鉴于热带地区的森林损失日益严重，森林碎片被搁浅在高度砍伐、边缘主导和退化的景观中，我们的研究强调了剩余森林碎片中昆虫食草的普遍增强——尤其是沿着森林边缘和森林内部的树冠间隙。因此，食草的增加可能会影响森林再生，并加速这些高度砍伐和受干扰的人为景观中的生态融化过程。