著者

佐々 朋幸 後藤 和秋 長谷川 浩一 池田 重人

出版者

森林立地学会

雑誌

森林立地 (ISSN:03888673)

巻号頁・発行日

vol.32, no.2, pp.43-58, 1990-12-30 (Released:2017-10-20)

被引用文献数

10

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They say, forests are being damaged in many parts of Europe, North America and Scandinavia by acid rain. In Japan also, the decline of adult Sugi tree (Cryptomeria japonica D. Don.) is going in urban areas, which is supposed by acid rain or acid materials from exhaust gases. The authors have an opinion that the influences of acid water will appear firstly on increase of soil acidity. Because, many kind of metals in soil will be exchanged to poisonous ions for tree fine roots or mycorrhizae, under such an acid soil condition. But, as it is extremely rare that rain water reaches forest floor directly without any touches on leaves, twigs, branches and stems, the water supplied to soil will certainly contain much amount of soluble nutrient elements derived from tree body, other than the amount in rain water. The other words, "the rain fall dropped on soil" means the throughfall or the stem flow changed in quality by such nutrient elements. The authors schement out a new method for collecting the stem flow and studied about the differences of acidity among rain fall, through fall and stem flow in relation to those nutrients' concentration. As the results of their study, they listed the following topics. 1) The acidity of stem flow always seems to converge to characteristic pH value in every species, independently of that of rain fall, as followings; Cryptomeria japonica: pH3.5〜pH4.1 Larix leptolepis: pH4.2〜pH4.8 Pinus densiflora: pH4.5〜pH5.2 Thujopsis dolabrata: pH5.0〜pH6.0 Fagus crenata: pH5.9〜pH6.5 2) The pH value of throughfall is always between that of rain fall and that of stem flow. 3) The pH value of stem flow is determined by multiple ionic action, not by single element. 4) The larger istheratio of(Ca+Mg+K+Na)/ organic-C in stem flow, the lower is the acidity. 5) The succeeding stem flow is different from the beginning one in the proportion between alkaline earth metals and alkali metals.