Process-based rainfall interception by small trees in Northern China: The effect of rainfall traits and crown structure characteristics

Rainfall interception by a tree's crown is one of the most important hydrological processes in an ecosystem, yet the mechanisms of interception are not well understood. A process-based experiment was conducted under five simulated rainfall intensities (from 10 to 150 mm h−1) to directly quantify tree crown interception and examine the effect of rainfall traits and crown structure characteristics on interception for broadleaf (Platycladus orientalis, Pinus tabulaeformis) and needle tree species (Quercus variabilis, Acer truncatum). Results indicated that (1) the interception process was composed of three phases, a rapid increase phase which accounted for approximately 90% of the maximum interception storage (Cmax), a relatively-stable phase, and a post-rainfall drainage phase in which 40% (±16%) of Cmax drained off to reach the minimum interception storage (Cmin); (2) Cmax and Cmin were only correlated with rainfall intensity for P. tabulaeformis; (3) Cmax and Cmin were correlated with both leaf traits (i.e., leaf area, leaf biomass, leaf morphology) and branch traits (i.e., branch density, branch count, branch length, woody surface area, and woody biomass), and the best predictors of Cmax and Cmin were biomass-related parameters; and (4) The needle species P. orientalis had the greatest Cmax, while the largest Cmin was observed in the broadleaf species A. truncatum. Our findings demonstrate the complexity of the interception process and tree characteristics may be more important in controlling interception than rainfall characteristics.