Effect of uncertainty in thermal emissivity
We did not measure leaf thermal emissivity (ε ), but assumed a fixed value of 0.98. To assess how a systematic difference in εbetween bald and hairy patches would have affected our results, we simulated cooling curves assuming ε was between 0.94 and 0.99 in bald patches but 0.98 in hairy patches, or vice versa. Additional details are provided in Supporting Information Methods S2. This analysis found that uncertainty in ε would have negligible effect on inferred differences in g bh between hairy and bald patches (Figs S2 and S3).