Fig. 1.

Effects of environmental variables on VOC emissions. Density distributions of mean standardized effect sizes of five environmental variables in six different VOC groups. The effect sizes (β-estimates) correspond to linear slope parameters derived from multivariable mixed effect models containing sampling year, study site, and local habitat manipulation as random effects (see SI Appendix, Table S1 and Fig. S1 for further details). All β-estimates are adjusted for seasonal variation in VOC emissions, assuming an increase in the spring and a decrease in late summer.