Generation of stemflow volume and chemistry in a mature Japanese cypress forest

Long-term monitoring of rainfall, throughfall and stemflow was conducted in a mature Japanese cypress forest at the University Forest in Chiba, Bose Peninsula, Japan. Two stemflow collectors were installed in a tree at 19.1 m (just under the tree crown) and at 1.3 m above the ground to determine the processes controlling the generation, volume and quality of stemflow at the stem, leaves and branches. The canopy-only stemflow and stem-only stemflow for this tree, and the canopy-and-stem stemflow for three other trees, were measured and sampled for chemical analysis. Total stemflow increased after installation of the 19.1 m collector just under the tree crown, suggesting a large water storage capacity of the bark. All ion concentrations: in stemflow except H+ were highest in the first sample collected during a rain event and declined thereafter. Hydrogen ion concentrations of canopy-only stemflow and canopy-and-stem stemflow were nearly balanced with the charge balance deficit (CBD) concentrations for all samples. Following comparison of ion concentrations among canopy-only stemflow, canopy-and-stem stemflow and throughfall, the ions were categorized into four groups (NO3-, SO42-, H+, CBD), (Na+, Cl-), (Mg2+, Ca2+) and (K+, NH4+). The groupings were based on differences in stemflow and throughfall chemistry generation processes between and among the groups. Copyright (C) 2001 John Wiley & Sons, Ltd.