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

AbstractLong‐term monitoring of rainfall, throughfall and stemflow was conducted in a mature Japanese cypress forest at the University Forest in Chiba, Boso 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 © 2001 John Wiley & Sons, Ltd.