Insect herbivory is known to augment emissions of biogenic volatile organic compounds (BVOCs). Yet few studies have quantified BVOC responses to insect herbivory in natural populations in pan-Arctic regions. Here, we assess how quantitative and qualitative BVOC emissions change with increasing herbivore feeding intensity in the Subarctic mountain birch (Betula pubescens var pumila (L.)) forest. We conducted three field experiments in which we manipulated the larval density of geometrid moths (Operophtera brumata and Epirrita autumnata), on branches of mountain birch and measured BVOC emissions using the branch enclosure method and gas chromatography-mass spectrometry. Our study showed that herbivory significantly increased BVOC emissions from the branches damaged by larvae. BVOC emissions increased due to insect herbivory at relatively low larvae densities, causing up to 10% of leaf area loss. Insect herbivory also changed the blend composition of BVOCs, with damaged plants producing less intercorrelated BVOC blends than undamaged ones. Our results provide a quantitative understanding of the relationship between the severity of insect herbivore damage and emissions of BVOCs at larvae densities corresponding to background herbivory levels in the Subarctic mountain birch. The results have important and practical implications for modeling induced and constitutive BVOC emissions and their feedbacks to atmospheric chemistry.

已知食草动物会增加生物挥发性有机化合物（BVOC）的排放。然而，极少有研究量化泛北极地区自然种群中BVOC对昆虫食草的反应。在这里，我们评估了北极北极山桦树上草食动物进食强度的增加，定量和定性的BVOC排放量如何变化（毛桦 变种 普米拉（L.））森林。我们进行了三个野外实验，在这些实验中我们操纵了几何蛾的幼虫密度（布鲁氏 和 秋梨），在山桦的分支上，并使用分支封闭法和气相色谱-质谱法测量BVOC排放。我们的研究表明，食草动物显着增加了受幼虫破坏的分支的BVOC排放。由于在相对较低的幼虫密度下食草，BVOC排放增加，导致最多10％的叶面积损失。食草动物也改变了BVOC的混合物组成，受损植物产生的互相关BVOC混合物比未损坏的植物少。我们的结果提供了对昆虫食草动物危害的严重性与幼虫密度下的BVOCs排放之间的关系的定量理解，而幼虫密度对应于北极北极白桦的背景食草水平。