Rainfall interception by tree crown and leaf litter: An interactive process

Rainfall interception research in forest ecosystems usually focuses on interception by either tree crown or leaf litter, although the 2 components interact when rainfall occurs. A process-based study was conducted to jointly measure rainfall interception by crown and litter and the interaction between the 2 interception processes for 4 tree species (Platycladus orientalis and Pinus tabulaeformis represented needle-leaf species, and Quercus variabilis and Acer truncatum represented broadleaf species) at 3 simulated rainfall intensities (10, 50, and 100 mm hr⁻¹). Results indicated that (a) crown and litter interception processes incorporated 3 phases: the dampening phase, the steady saturation phase, and the postrainfall drainage phase, but the dampening phase for litter interception usually lasted 30 min longer than for crown interception; (b) the maximum and minimum interception storage (C_max and C_min) for the crown were 0.63 and 0.36 mm on average, and litter C_max and C_min were 5.38 and 2.36 mm, respectively; (c) generally, crown and litter C_max and C_min increased when gross precipitation increased significantly (p <.05) from 10 to 100 mm; and (4) crown C_max and C_min for needle-species were 1.8 and 1.2 times larger than broadleaf species, whereas broadleaf litter showed the opposite, its C_max and C_min were 2.0 and 1.6 times larger than needle-leaf litter on average; however, no significant differences were observed in crown and litter C_max and C_min between species on per leaf area and litter thickness basis. Results were normalized by total leaf area and litter thickness to provide a way to scale up from young trees to mature forests. Overall, rainfall interception was affected by biotic and abiotic factors together and could be quantified via multiple linear regression functions.