The purpose of this paper is to clarify the patterns of forests damage on various site condition. The relationships between the forests damage patterns and site condition were discussed. There are three reason for forest damage in this area. One reason, the forests damage was caused by typhoon. The dead trees became like bleached bone. The site condition in the dead tree area is very similar at each study area: the direction of the wind is blowing from south-east. Topography is characterised by the mountain top and upper parts of ridge. In addition to these dead tree area, the small patches of dead trees appeared on the top of the ridge in direction of north-west slope blowing over from south-east wind. The growth of advanced seedlings in closed forest is very slowly but under the open canopy it is so fast. Consequently, changes of growth patterns were proved to be destroyed the canopy by typhoon or other reason. The results of annual ring analysis suggest the forests damage was caused by typhoon, in 1982. Second, the forest damage was occurred by seasonal wind at mountain top and ridge as mountain effect. The third reason is landslide, especially, top and side edge of big volcanic land slide area. According to newspaper, the forest damage in this area was occurred by acid rain. But we can not ditect the dead trees caused by acid rain except for a little leaves discoloration, but the causes were unknown. Currently, the forest damage in this area is considered as the one type of natural regeneration.

View full abstract

[in Japanese]

View full abstract

Soil changes after a catastrophic blowdown of coniferous forest, due to a typhoon in 1954, have been monitored for approximately 40 years. Monitoring sites were established in locations where the vegetation and soil had been surveyed 2 years before the typhoon. The type of humus layer, soil pH, carbon and exchangeable Ca concentration were monitored approximately every 4 years. Humus type of Mor and Moder sites changed to Mull type within 6 years after the typhoon, but the Mull type sites did not change their humus type during the observation period. Soil pH, carbon, and exchangeable Ca concentration had been increasing after the typhoon in Moder and Mor type sites. These trends began to decrease 14-22 years after the typhoon. The changes of these chemical properties in Mull sites were small and a clear trend of changes could not be detected. We suggest that those chemical changes detected were caused by a decomposition of humus layers after the typhoon and an accumulation of organic layer with recovering forest vegetation. Another several decades might be necessary for recovery of the soil properties similar to the pre-disturbance level.

View full abstract

In a mixed deciduous broad-leaved forest whose tree density was 1980 trees/ha, the experiment of thinning was conducted. After 18 years from the experiment, the effects of thinning on diameter-growth and wood quality were studied for three predominant species, i.e. Castanea crenata SIEB. et ZUCC., Purunus sargentii REHD. and Magnolia obovata THUNB., and others. Diameter growth rates of C. crenata, and P. sargentii, differed among the four plots, i.e. 300 trees/ha, 400 trees/ha, 500 trees/ha, and non-thinning plot. The growth rates in non-thinning plot was slower than in thinning plots, especially in trees of smaller diameter size. The other hand, the rates of M. obovata, and Aesculus turubinata BLUME, did not differ among the four plots. Wood quality was checked using the relationships of air-dried density and modulus of elasticity in bending to the mean width of annual ring. Both relationships showed no correlation with the stand density in P. sargentii, and M. obovata, (diffuse-porous wood). Weak positive correlation was detected in C. crenata, (ring-porous wood) with these relationships. Thus, it was clarified, the thinning of mixed deciduous broad-leaved forest promoted the diameter growth rate of some species, but the wood quality of them did not become worth after the thinning.

View full abstract

Community structure of a mixed koyean pine (Pinus koraiensis) hardwood forest was studied by tree (over 2m in height) census in nine quadrats located in Xiaobeihu Forestry Area in Ningan District, Heilongjiang Province, northeastern China. Pinus koraiensis dominated in stands on mountain side. Further, this species attained second dominance in stands with dominant of Larix olgensis or Ulmus japonica on wet sites. The forests with dominant of Korean pine on mountain side, usually had two or three layers in their stratification diagrams. Pinus koraiensis dominated in tree layer, Tilia amurensis and Abies nephrolepis did in sub-tree and/or shrub layer and Acer spp. did in shrub layer. Regeneration of P. koraiensis occurred sporadically beneath the canopy of P. koraiensis in undisturbed stands and did vigorously under the canopy of Populus koreana and Betula platyphylla forest established after fires.

View full abstract

In a Fagus crenata Blume forest on Mt. Mikuni on the Pacific side of Central Japan, emergence and establishment of beech seedlings were studied in 1994 following a mastyear. Desiccation, animal-damage, insect-damage and fungi-damage were main factors for seedling death. Some seedlings died immediately after germination, due to taking off by mice, feeding by animals, and desiccation, indicating that less snow cover on the Pacific side has unfavorable effects on seedling establishment. Density of current-year seedlings at the end of the growing season was similar or more compared to that in beech forests well-regenerating on the Japan Sea side. It is thus concluded that, in the process of sound nut supply and establishment of current-year seedlings, there are no inhibiting factors against regeneration of beech forests on Mt. Mikuni. Because relative illuminance at the forest floor is very low (mean value of 2.2%) due to high density (3194 No./ha) stools in the study site, growth and survival of seedlings older than 2 year might be inhibited.

View full abstract

At one time bare hills caused from intense human impacts were widely distributed in the Kinki and Setouchi district, and most of them were afforested later. But soil conditions in these areas are rather immature even now. Development process of immature soils in these bare hills were studied with special reference to their mineralogical changes, weathering of primary minerals and forming of clay minerals. Study areas were Mt. Tanakami (granite area), Shiga prefecture and Mt. Mikusa (rhyolite area), Hyohgo prefecture. As for the primary mineral composition of granite soils, contents ratios of feldspars, mica and other minerals changed corresponding to the soil development. On the other hand clear changes couldn't be seen as for the rhyolite soils. But both on granite soils and on rhyolite soils interesting tendency for particular heavy minerals such as magnetite and zircon to be concentrated with soil development was found out. And it was suggested concentration ratio of heavy minerals might be used for quantitative indicator of weathering stage. Clay mineral composition of granite soils shows the process that feldspars and mica partly altered to kaolin minerals in early stage of soil genesis, and in later stage 14Å-minerals and gibbsite were formed. As for the rhyolite soils 14Å-minerals has been formed slightly even in the early stage, and it increases gradually in contrast with decrease of feldspars with soil development. From these results 3 or 4 stages of soil maturity could be presumed both on the granite soils and on the rhyolite soils respectively.

View full abstract

Invasion and establishment of tree species was surveyed in a part of the Oi Wharf. This is one of the reclaimed land in Tokyo Bay, formed by infill of waste materials and discarded soil. The vegetation of the study site was composed of perennial grass and herb communities dominated by the anemochorous plants such as Phragmites australis, Solidago altissima, Imperata cylindrica var. koenigii, Miscanthus sacchariflorus. The invaded trees scattered in the site were abundant under the electric cables and along the drains. Trees taller than 3m in height tended to be distributed near the drains. As almost all the tree species which appeared on the site (Prunus jamasakura, Celtis sinensis var. japonica, Rhaphiolepis umbellata var. integerrima, Ligustrum japonicum etc.) were endozoochores, their seeds seemed to have been dispersed by birds. The source of these seeds was thought to be the mature trees planted in the parks near the site. The electric cables act as perches, accounting for one of the trends of tree invasion. Since construction of the drains prohibits the expansion of those perennial grasses and herbs which make clonal growth by rhizomes, loosen soil compaction and extreme wet condition of soils, the areas adjacent to the drains must be suitable sites for the establishment of tree seedlings. The abundance of endozoochorous trees among the invading trees is a common characteristic of isolated forests in urban habitats. Thus, tree invasion on a reclaimed land seems to be influenced by the urbanization of surrounding areas. Moreover the C. sinensis var. japonica forest and the M. japonicus forest will be involved in the early tree phase of succession in the reclaimed land of Tokyo Bay.

View full abstract

Seasonal changes of leaf water relations of 4 evergreen Taxodiaceae species, Cryptomeria japonica D. Don, Taiwania cryptomerioides Hayata, Cunninghamia lanceolata Hook and Sequoia sempervirens Endl., and 2 deciduous Taxodiaceae species, Metasequoia glyptostroboides Huet Cheng, Taxodium distichum Rich., were investigated, referring to the low temperature effects on the water relations. For each species, shoots were collected from one to three trees planted in the Tokyo University Forest in Chiba and water relations of current-year leaves were measured with pressure-volume curve technique. Ψ^<sat>_s and Ψ^<tip>_w of M. glyptostroboides decreased in October compared to August while those of Taxodium distichum in October showed little change from August. All 4 evergreen species showed the lowest Ψ^<sat>_s and Ψ^<tip>_w in February, when the monthly mean of daily minimum temperature decreased near to 0℃. Among the 4 evergreen species, T. cryptomerioides and C. lanceolata showed decreases of Ψ^<sat>_s and Ψ^<tip>_w in October compared to those in August, while those of C. japonica and S. sempervirens showed no decrease in October. These differences might reflect the differences of the low temperature sensitivity among the 4 species.

View full abstract