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Volume 32 (1970)
- Issue 6 Pages 129-
- Issue 4-5 Pages 83-
- Issue 3 Pages 43-
- Issue 1-2 Pages 1-
Volume 32, Issue 1-2
Displaying 1-6 of 6 articles from this issue
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[in Japanese]1970 Volume 32 Issue 1-2 Pages 1-3
Published: January 30, 1970
Released on J-STAGE: July 23, 2009
JOURNAL FREE ACCESSDownload PDF (628K) -
Masami KITAMURA, Shoji SUTO, Hidehiro ISHIBASHI1970 Volume 32 Issue 1-2 Pages 4-9
Published: January 30, 1970
Released on J-STAGE: July 23, 2009
JOURNAL FREE ACCESSThe relation between the depth of snow on the young stand of Sugi (Cryptomeria Japonica) in the Forest of Yamagata University and the micro-topographic factors was investigated with the aid of partial and multiple correlation coefficients. The measurements of depth of snow were made from December in 1964 to May in 1965. Summary of the findings is as follows :
1) In the first half of the duration of snowfall the depth of snow is not affected very much by the micro-topographic factors and the stand composition, but in the latter half it is affected remarkably by the above factors as the day goes on.
2) On the steep slope, the convex surface and the place which has a lot of light supply the depth of snow decreases rapidly during the spring thaw. On the other hand the depth of snow decreases slowly on the place which has many trees over 6 m in height.View full abstractDownload PDF (974K) -
Masayuki ISHIKAWA, Toshitsugu KAWAGUCHI, Shohei SATO1970 Volume 32 Issue 1-2 Pages 10-17
Published: January 30, 1970
Released on J-STAGE: July 23, 2009
JOURNAL FREE ACCESSEstimation methods of snow depths by tree forms of Japanese cedar and Japanese larch were studied.
The absolute maximum depth of snow (H) in 10 years can be estimated by the following formula
H=H1
H=H2+0.5
H=H3+0.4 (unit : meter)
where H1; hight of drooping branches of Japanese cedar caused by the settling force of snow
H2 ; height of scars of tree trunks of Japanese cedar caused by bending of treetop under snow cover at an early age
H3; height of scars on the trunks of Japanese larch caused by the settling force of snow at the time of the breaking off of branch
The drooping branch method is applicable on steep slopes and the smallest sample numbers are required for the estimation. When the branches of Japanese cedar have been pruned off or the boundary of the drooping branches is not clear, then the trunk scar method or the broken branch method is applicable.View full abstractDownload PDF (6567K) -
Masayuki INUMA, Toshimi KURITA1970 Volume 32 Issue 1-2 Pages 18-22
Published: January 30, 1970
Released on J-STAGE: July 23, 2009
JOURNAL FREE ACCESSSince snow pressure acting on buried items under the snow varies depending their shape and surface area the resulting snow damage of young trees is exceedingly complicated. Thus silviculutural countermeasures to prevent snow damage must be taken while taking into consideration problems from the side of the tree.
Hence the present writers carried out a survey on the relation of snow damage of trees with regard to stem form and root system in young cryptomeria forests in heavy snow regions at the foot of Mt. Gassan in the Yamagata Prefecture.
(1) Many trees exposed on the snow surface showed stems with elliptical cross sections in which the long axis was in parallel with the slope line at the lower parts. While the trees buried under the snow generally showed stems with a circular cross section or elliptical shape with the short axis in parallel with the slope line. A high degree of snow damage was found in trees having circular cross sections.
(2) Trees having severely bend and loosely rooted stems at the lower part were buried under the snow and had a high degree of snow damage. These feeble stem forms seem to be caused by the insufficient development of root systems as compared with the upper parts of trees.View full abstractDownload PDF (828K) -
Shigeo WATANABE, Seiichi NEZU, Daikichi UMEYAMA1970 Volume 32 Issue 1-2 Pages 23-29
Published: January 30, 1970
Released on J-STAGE: July 23, 2009
JOURNAL FREE ACCESSThe purpose of this investigation is to make clear the states of snow cover in the heavy-snow area of which Cryptomeria japonica-trees are damaged by snow pressure very often. Gomisawa Plantation, young stands of C. japonica is in the heavy- snow area of Niigata Prefecture. On the various topographic places of this plantation, maximum snow cover depth, snow pressures and the vertical section of snow cover were investigation in the snow seasons of the years 1965-1969. The results are as follows :
1) The course of snow cover depth during each winter at Gomisawa has a strong resemblance to that of Tôkamachi Site.
2) It seems that the heavy-snow year over 500 cm in maximum depth on the flat stand occurred five times within last twenty years.
3) It is estimated that the duration of continuous snow cover range 160-190 days on the flat stand.
4) The maximum snow cover depths are considerably changed with topography, wind direction and climatic condition in each winter. They range from 310 to 750 cm or more in the heavy-snow year, and from 290 to 470 cm in the year of small depth. In addition, always they are shallow on the windward slopes, and are deep on the leeward slopes. Therefore, the snow pressures on inclined stands show remarkably large values onthe leeward slopes. The settling pressures of snow on flat stands range from 2.4 to 3.0 times as great as those of Tôkamachi Site.
The states of snow cover mentioned above are closely related with the damage of the forests.View full abstractDownload PDF (8607K) -
Keiji TAKAHASHI, Kikumatsu TAKAHASHI1970 Volume 32 Issue 1-2 Pages 30-36
Published: January 30, 1970
Released on J-STAGE: July 23, 2009
JOURNAL FREE ACCESSThe purpose of this investigation is to find out a dangerous topography for the planting of Cryptomeria japonica in the heavy-snow area of Niigata Prefecture. Twenty-two plots of C. japonica stands ranging 26-53 years old were surveyed and the topographical changes of the damage by snow pressure were examined.
The forest stands in this area have the maximum snow depth ranging 3.0-4.0 meters on the average, and the deepest extremes in the last ten years at the sample plots ranged from 3.7 to 5.4 meters. Most frequent wind direction in winter in this area is NW.
The snow damage of the forests is influenced by the direction of slope, inclination angle, snow cover depth, site on the slope, etc., especially by the direction of slope. In north and east slopes, the ratios of undamaged trees to standard number of yield table range from 0.54 to 1.06, and the average shows 0.79. However, in south and west slopes, they range from 1.00 to 1.50, and the average shows 1.24. Therefore, the planting of C.japonica in north and east slopes of this area is very dangerous, especially in gentle slope under 10° on the lower part of inclined place and in steep slope over 35°.
Generally speaking, the damage of the forests on inclined place over 10° in angle become more and more conspicuous with the increase of snow depth and of inclination; besides the ratios of undamaged trees in the lower part of inclined place are lower than those in the upper.View full abstractDownload PDF (3413K)
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