Amplification of plant volatile defence against insect herbivory in a warming Arctic tundra

Supplementary data for the article:Li et al. (2019). Amplification of plant volatile defence against insect herbivory in a warming Arctic tundra. Nature Plants. http://dx.doi.org/10.1038/s41477-019-0439-3 The study employs long-term in situ warming to assess the impacts of warming and insect herbivory on plant volatile organic compound emissions from the widespread circumpolar dwarf birch (Betula nana), a major player in ongoing Arctic greening. The experiment comprises open top chambers in place during summer on an arctic tundra heath in northern Sweden for 8 and 18 years in a randomized complete block design. The study involves three independent experiments. The first experiment describes the impacts of experimental warming and mimicked insect herbivory (exogenous application of methyl jasmonate) on Betula nana volatile emissions (n=18). The second experiment describes volatile emission kinetics of Betula nana upon either real insect herbivory (autumnal moth, Epirrita autumnata) or mimicked insect herbivory (n=4). The third experiment describes the effects of experimental warming on insect herbivory pressure on Betula nana (n=18).