Rainfall characteristics affected canopy rainfall redistribution more than canopy structure and leaf micromorphology in three urban forest species in China

Abstract

Rainfall redistribution in urban forests is a critical component of urban hydrological cycle, influencing runoff regulation and rainwater utilization. This study examined three urban forest species (Cinnamomum camphora, Sophora japonica, and Platanus orientalis) in Hefei, China, across 20 rainfall events during 2022–2023. Canopy interception, throughfall, and stemflow were monitored, and the effects of rainfall characteristics, canopy structure, meteorological factors, and leaf functional and microstructural traits were assessed. Throughfall was the major component, averaging 17.3–17.6 mm for the three species, followed by canopy interception (4.0–4.3 mm), and stemflow was minimal (0.06–0.1 mm). Rainfall characteristics greatly affected redistribution, particularly rainfall amount, which exhibited a linear positive correlation. Redistribution tended to increase initially and then stabilize with longer rainfall duration and higher intensity. Interception and throughfall were largely independent of canopy structure and other meteorological factors, whereas stemflow was negatively related to tree dimensions. Plant storage capacity was influenced by plant size, biomass, leaf wettability and microstructure, but these effects were attenuated for rainfall redistribution under natural rainfall conditions. These findings highlighted that rainfall characteristics primarily determined redistribution, with minor contributions from leaf and canopy traits, providing valuable insights into the regulatory mechanisms of urban green infrastructures on ecohydrological processes.