On early August, 1982, a climax subalpine coniferous forest in the South Japanese Alps, dominated by Abies mariesii and A. veitchii, was severely damaged by the Typhoon No. 10. Among trees more than 4.0cm in DBH, 95.6% were damaged. The stem broken trees made up 54.0% of damaged trees and the rest were uprooted trees. The regeneration process of the forest were studies on the basis of annual ring data of damaged trees. The age class distribution was discontinuous and three age groups, less than 90 years, between 90 and 180 years, and more than 180 years were distinguished. The oldest trees were 286 years old for Picea jazoensis var. hondoensis. The results of annual ring analysis showed that synchronous and rapid increase in diameter growth occurred several times. This indicate that small scale disturbances occurred several times in the forest. It seemed that many trees established in relation to disturbances occurred about 200 and 100 years ago.

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The deposited amonts of acidic materials on leaves of Abies at Mt. Norikura, Gifu Prefecture, were measured by using the leaf washing method, and with these measurements the minimum pH of fog in the subalpine forest area was estimated. The resulting minimum estimated pH level was about 3.6. We concluded that the load of acidic materials was not so severe compared with the acidic condition applied in usual chaamber experiments by which some visual effects of acidic fog on leaf surface were detected. Many seedings and saplings are found among the dead trees of large diameter in the forest stands at Mt. Norikura. This means that these forest stands are in the regeneration stage. Although no obvious evidence was found that acidic deposition caused the decline of these stands, more successive and comprehensive research have to be performed to make clear the effect of atmospheric pollutants on subalpine trees.

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Formation process of a mixed coniferous forest composed of Pinus parviflora var. pentaphylla, Thujopsis dolabrata var. hondai and Tsuga diversifolia on the ultrabasic rocks was investigated by annual ring chronologies in the northern area of Mt. Hayachine, northeast Honshu, Japan. The stand is regarded to have been formed under the influence of an intensive disturbance affecting a vast area at the end of the 17th century. Relatively slight disturbance also would have occurred around 1880. The Pinus recruited simultaneously, grew rapidly after the intensive disturbance and became the canopy trees prevailing over other species. The recruitment of the Thujopsis and Tsuga was carried out by advance regenerated saplings and they continued relatively slow growth after the intensive disturbance. Abies mariesii recruited in the undergrowth after the regenerated Pinus, Thujopsis and Tsuga formed a closed canopy layer, and grew extremely slowly. Broad-leaved species such as Betula spp. and Magnolia hypoleuca recruited after the slight disturbance and grew rapidly. The intensive disturbance which caused the forest regeneration may have been human disturbances such as logging.

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Decline of Yezo spruce (picea jazoensis (Sieb. et Zucc.) Carr.) forest has been recently noticed in Hokkaido. In this experiment comparison of microorganisms isolated from the Yezo spruce roots from declining and healthy stands was obseved. Fine roots of Yezo spruce were collected from declining and healthy stands in the Tokyo University Forest in Hokkaido, Furano, Japan. Soil-free roots were homogenized in sterilized water and the number of total bacteria, nitrogen-fixing bacteria, actinomycetes, and fungi in the suspension were estimated. In general, the number of total bacteria and actinomycetes of the roots from the declining stand was larger, while the number of nitrogen-fixing bacteria was much smaller than healthy stand. Bacteria were randomly isolated from the agar plates, and the physiological characteristics of each isolates were examined. Bacterial flora from the healthy stand was diverse, while rather restricted groups were majorities in the isolates from the declining stand.

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