Abstract
The through fall and stem flow were examined for 17 years old manmade forests of Todo fir (Abies sachalinensis) and Ezo spruce (Picea jezonensis) in the suburbs of Saspporo from May, 1990 to November, 1990. The amounts of through fall, stem flow and outer rainfall were measured at every rain event, and they were analyzed for, pH, EC and base cations concentrations. Also pH and EC of the surface soils at stem base and in berween trees were measured to know the influence of the through fall and stem flow on soil. The rsults obtained are summarized as follows. 1) Proportion of the amount of stem flow to total precipitation was higher in the Todo fir forest (10%) than in the Ezo spruce forest (5%). 2) The pH value was generally the lowest for the outer rainfall, then increased in the order of Todo fir stem flow < Todo firthroughfall < Ezo spruce throughfall < Ezo spruce stem flow throughout the period. The EC was higher for the through fall and stem flow than for the outer rainfall. 3) The base cations concentrations of the throughfall and the stem flow increased in the spring and the autumn, and the increases seem to take place cooncomitantly with leaf development and defoliation, respectively. Details of the time function of each base cation level differed depending on the tree species and the kinds of rainwater. 4) The amount of H ion loadedto thesoil during the period was smaller in the Todo fir forest (15 meq/1 m^2) and Ezo spruce forest (12 meq/1 m^2) than in the outside of the forests (34 meq/1 m^2). The loaded amounts of each base cation in the forests were similar between the species, and increased by respective 2 times, 1.5-2 times and 20 times for Ca, Mg and Na, and K in comparison with the outside of the forests. 5) The pH value of the surface soil was lower at stem base than in between trees in the Todo fir forest, while the reverse was the case in the Ezo spruce forest, presumably because of the inter-species differences in rainfall distribition into throughfall and stem flow and their qualities.
