Canopy interception of rain, dew, and fog occurs in ecosystems worldwide. A ubiquitous effect of leaf wetness on plant water balance is the interference of the water droplets with the leaf energy balance, which increases leaf albedo and emissivity and decreases leaf temperature through droplet evaporation. This in turns affects the vegetation carbon uptake rate, with potential consequences for the whole global carbon cycle. Here, I use the specific example of dew deposition to understand how leaf wetness affects water and CO2 fluxes of plants. First, I will present a simple leaf energy balance that characterizes the effect of deposition and the evaporation of dew on transpiration and carbon uptake. The model is driven by five common meteorological variables and is used to explore the tradeoffs between energy, water, and carbon balances for leaves of different sizes across a range of environmental conditions. I will then present results from a laboratory experiment
where Colocasia esculenta leaves were misted with isotopically enriched water to mimic canopy interception. Leaf water isotopes and water potential measurements corroborates the results of the model.