Effects of air pollution on the tree growth and vigor on the Japan Sea coast-a dendrochronological study-

1.在位于日本本州中部日本海一侧的福井县堺县的两个热电厂周边地区，研究了低水平空气污染对各种树木元素的影响，包括日本杉木、密植松、松和许多其他阔叶常绿和落叶树木。自1974年以来，对全区树种视觉损伤程度的监测持续了23年，本报告汇编了1995年和1996年的视觉损伤实地调查结果。目前这个地区没有一棵没有视觉损伤的树，这反映了空气污染的影响。形态学和生理学症状也进行了检查。通过树木年代学研究，评价了空气污染对杉木生长的影响。人们认识到空气污染水平与树木年轮生长下降之间存在显著的相关性。树木年轮分析也显示了生长抑制作用。近40年来，以日本西南地区为代表的松林因松枯萎病大面积遭到破坏。在本研究中，我们研究了被松树枯萎病杀死的松树的径向生长，以阐明空气污染和/或酸沉积等环境胁迫如何影响疾病的发展。100年以上的老树径向生长随空气中SOx的增加而减少。然而，这些树木即使在压力下存活下来，当它们恢复生长时却突然被杀死了。

1.The effects of low level air pollution on various tree elements, including Cryptomeria japonica (Japanese Cedar), Pinus densiflora, Pinus thunbergii, and numerous other broad-leaved evergreen as well as deciduous trees, have been studied in the surrounding area of two thermoelectric power stations in Sakai-gun, Fukui Prefecture, on the Japan Sea side of central Honshu, Japan. The monitoring on the degree of visual injury of tree species in the whole area has been cotinued for 23 years since 1974, and in the present report the results of the field survey on the visual injury during 1995 and 1996 are compiled. There are no trees at present without any visual injury in this area, reflecting effects of air pollution. Morphological and phyiological symptoms were also examined.2.A dendrochronological study was also carried out to evaluate the effects of air pollution on the increment growth of Japanese Cedars. Conspicuous correlations between the levels of air pollution and decline in tree ring growth were recognized. The growth inhibition was also revealed by the tree ring analysis.3.Pine forests consisting of Pinus densiflora and P.thunbergii have been devastated by pine wilt disease for past 40 years in the large areas, especially in the southwestern part of Japan. In the present study we have examined radial growth of pine trees which were killed by pine wilt to elucidate how environmental stresses such as air pollution and/or acid deposition affect the disease in its development. Aged trees, about 100 years old or more, show reduction in radial growth in accordance with SOx increase in the air. However, such trees, even though survived under the stress, were abruptly killed when their growth recovered.