Relationship between Throughfall Kinetic Energy and Tree Height, Crown Bottom Height, and Crown Length for Japanese Cypress Plantation

Abstract

Summarizing seven studies that measured throughfall drops in Japanese cypress (Chamaecyparis obtusa) plantation, we found positive correlation between kinetic energy of throughfall normalized by rainfall (KE_N; J m⁻² mm⁻¹) averaged in several rainfall events and crown bottom height but negative correlation between KE_N and crown length. The results suggest the increase of fall velocity of drips with increasing crown bottom height, and the increase of the opportunities that drips splash on lower layer foliage with increasing crown length. An empirical equation for estimating KE_N from crown bottom height and crown length was developed. The equation will be useful for assessing infiltration, overland flow, and soil erosion on bared forest floor in Japanese cypress plantations reflecting difference in canopy structures.