Studied on the diffusion of acid fallout and the succession of urban forest in Kyoto City

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The purpose of this study is to clear the characteristic of rainfall in Kyoto City and to clear the stand structure and the dynamics of urban forests. To achieve this object, we collected the rainfall here and there in Kyoto City, and besides at 4 points in Kansai District using commercially sold acid rain collector. And we investigated at the permanent plots of the secondary stand which were established from 1980 locating in the northern part about 20 km distant from the town area of Kyoto CitypH at the beginning of rain was 3 level everywhere. And pH was increasing and EC was decreasing gradually in the progress of time. pH was the highest and EC was the lowest in the depths of mountain. pH was lower and EC was higher in the forest behind a industrial area, and there pH and EC hardly changed in the progress of time as compared with Kyoto City.In Kyoto City pH was higher in northern and eastern parts. Though in center of the town area EC was higher, pH were not so low generally, but pH was the lowest and EC was the highest near the highway. And it was expected that the rain was acidified by increasing of the rate of NO_3^- in pH lower area, but it may well be neutralized by increasing of the rate of NH_4^+ in centerThe investigated forests were consisted of many types stands. In mixed stands of Castanea crenata and Quercus mongolica var. grosseserrata where we could see frequently in this area the species in the lower story decreased and now the species of the light demanding tree were decreasing in the upper story gradually, too.