Chemical Compositions of Throughfall and Stem Flower under Mixed Forests. An Example in Misumai Experimental Site

1989

S. 829-846

13 Abb., 1 Tab., 8 Lit. Ang.

Unselbständiges Werk

200037127

The chemical composition of precipitation, throughfall and stem flow was investigated at the Misumai Experimental Site near Sapporo. Three kinds of throughfalls (that from Larix kaempferi, Abies sachalinensis, and deciduous woods) and four kinds of stem flows (that from Larix kaempferi, Abies sachlinensis, Juglans ailanthifolia, and Fraxinus mandshurica var. japonica) were sampled to compare their ionic concentration and chemistry. The pH of precipitatin at this site was in the range from 4.02 to 6.77 and the frequency of acid rains was rare. The EC of precipitation was lower than (Formel) except for the samples from November, whose EC levels were about (Formel) due to the wind-borne salt originating from sea water. The ionic concentration of throughfall was higher than that of rainfall owing to the leaching of ion from the leaves and/or the dissolution of dry-deposits accumulating in the crown. As for the throughfall of deciduous trees and Larix, the ionic concentration increased in fall due to the leaching of ions from the autumn leaves which had changed colors. In case of the throughfall of Abies, however, such an increment could not be observed. A distinct peak indicating a high ionic concentration was also recognized inthe throughfalls of deciduous trees after a long dry spell which was attributed to the accumulation of dry-deposits on the surface of broad leaves. The ionic concentration of stem flow was also higher than that of rainfall. But the magnitude of the increment depended upon the status of the stem surfaces on which the stem flows ran down. The stem flow of Larix, which passed down the rough surface of the stem and had a long contact time, had the highest ionic concentration among the stem flows examined. Potassium, sodium and chlorine were the most important inorganic elements inthe throughfalls and stem flows examined. Besides inorganic substances, many organic substances leached from the trees were also included. The low pH of the Larix stem flow was closely related to the organic acids included with the other organic substances.