Urban tree canopy processes affect the volume and biogeochemistry of inputs to the hydrological cycle in cities. We studied stemflow in isolated deciduous trees in a semiarid climate dominated by small precipitation events. To clarify the effect of canopy traits on stemflow thresholds, rates, yields, percent, and funneling ratios, we analyzed branch angles, bark relief, tree size, cover, leaf size, and branch and leader counts. High branch angles promoted stemflow in all trees, while bark relief influenced stemflow differently for single- and multi-leader trees. The association between stemflow and numerous leaders deserves further study. Among meteorological variables, rain depth was strongly correlated with stemflow yields; intra-storm break duration, rainfall intensity, rainfall inclination, wind speed, and vapour pressure deficit also played roles. Greater stemflow was associated with leafless canopies and with rain or mixed events versus snow. Results can inform climate-sensitive selection and siting of urban trees towards integrated rainwater management.
