Embolism does not spread outwards from simulated herbivory damage sites in leaves

Embolism is known to occur in leaf venation networks as the leaf dries out. This process is associated with reduced leaf hydraulic conductance that can impact transpiration and photosynthesis. We hypothesize that herbivory or other leaf mechanical damage could introduce additional air into the leaf, leading to further venation-mediated embolism spread during drought. Using the optical vulnerability method, we compared embolism spatial spread rates after either midrib or lamina damage in two species of contrasting venation architecture (pinnate vs. palmate). We then tested the hypothesis that embolism would spread faster near damage locations. We found that there was no consistent effect of damage but rather substantial spatial heterogeneity in how damage influences leaf hydraulic conductance. Herbivory damage and hydraulic damage may have independent effects in the studied species.