Objective The rainfall interception by plant canopy plays an important role in reducing stormwater runoff, and the water absorption performance of plant leaves is closely related to the ability of plant canopy to intercept rainfall.
Method In order to evaluate the interception ability of plant canopy, the leaf water absorption, canopy interception quantity and canopy interception volume of 21 plant species in Beijing were calculated by water immersion experiment, field measurement and aerial image analysis.
Result Research showed that: (1) the relationship between water absorption and immersion time was logarithmic; (2) the water absorption process of plant leaves can be divided into three stages. The water absorption process of trees and shrubs was similar. The mean water absorption of leaves at 20 min was 0.17 and 0.05 g, respectively; the mean water absorption of leaves at 80 min was 0.18 and 0.06 g, respectively; and the mean water absorption of leaves at 120 min was 0.18 and 0.06 g, respectively. The average water absorption of herb leaves was 0.13 g at 20 min, 0.27 g at 40 min, and 0.21 g at 120 min; (3) the canopy rainfall interception of 11 arbor species was between 71.30 and 738.72 g/m2, and the canopy rainfall interception of 6 shrub species was 41.79−275.28 g/m2, the canopy rainfall interception of 4 herb species ranged from 57.82 to 217.49 g/m2, and the canopy interception of evergreen conifers was significantly higher than that of deciduous broadleaved plants; (4) canopy interception of some shrubs and herbs was higher than that of some arbors, such as Buxus sinica and Iris tectorum; (5) the plant canopy interception volume was positively correlated with canopy cover area and plant canopy interception quantity, the evergreen coniferous tree + evergreen shrub + herb combination had the largest canopy interception volume; (6) the ratio of average annual rainfall interception of the Cedrus deodara +Buxus sinica + Iris tectorum community canopy to the total rainfall was 11.57%, which had a significant interception effect on small rainfall events.
Conclusion Different plant types and configurations have an impact on urban green space rainfall interception capacity. This study can provide reference for the construction of high retention capacity plant communities and sponge city green space construction.