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).