Hierarchical partitioning analysis of leaf trait effects on chewing damage in the field trial (n = 20). The data presented are I, the independent contribution of leaf traits to variance in chewing damage, expressed as a percentage of the explained variance, with statistical significance (*P < 0·05) derived by randomization procedures (Walsh and Mac Nally, 2013). ‘L’ indicates data were log-transformed for analysis. Chewing damage was also log-transformed. When mechanical traits were analysed alone to include tear tests (n = 17), again, only specific work to shear made a significant independent contribution (I = 19 %; P < 0·05) to chewing damage