Surface storage of rainfall in tree crowns: not all trees are equal

Urban forests can be an effective strategy for managing stormwater. The soil that supports tree growth acts like a reservoir that reduces runoff. The tree crown intercepts rainfall on leaves and stems and its evaporation reduces water reaching the ground below. Until now surface storage capacities have been studied only for forest trees. Based on forest research, green infrastructure accounting tools have assumed a storage depth of one millimeter, regardless of species. We used a rainfall simulator and branch cuttings of 20 tree species in Davis, CA to measure the depth of surface storage under a variety of rainfall conditions. Potential storage capacity is modeled for 40 years using tree growth equations and storage depth values.