Results
When considered across all experimental treatments (Fig. 2), we find
evidence for negative effects of insect herbivory on willow shoot
growth, and for a mix of negative and positive effects of climate (Fig.
2a). These climate effects generally became more positive with warming,
such that at cool climate conditions (low GDD), warming climate
conditions were associated with declines in shoot growth, whereas under
warmer conditions, further warming had either no effect, or weakly
positive effects (Fig. 2b). The joint outcome of these patterns was that
under cooler climate conditions, insect herbivores had relatively weak
effects on willow shoot growth, whereas under warmer conditions, the
negative effects of insect herbivory on shoot growth became more
pronounced (Fig. 2c).