We selected two malesterile sugi (Cryptomeria japonica D. Don) trees (M-1, M-2) from 10, 902 Tateyama-sugi seedlings. By observation, both male and female flowers appeared to be almost normal. However, no pollen grains were dispersed from the male flowers in pollination season. The inside structures of the male flowers appeared to be quite different from normal flowers under a scanning electron microscope. The open-pollinated seeds obtained from M-2 had normal germination ability, but the seeds of M-1 showed a low level of germination. The chromosome numbers of the two male sterile trees were 22, euploid. So, it was inferred that the characteristic is caused by the male sterile gene and this mutation occurrs at a frequency of 0.016 to 0.002% in sugi (Cryptomeria japonica D. Don). This selection method is effective because male sterile trees can be selected in few cultivation areas and short terms.

View full abstract

The podocarp bark borer, Hirticlytus comosus (Matsushita), is one of the most serious pest insects of Podocarpus macrophillus (Thunb.) In order to study the characteristics of the distribution pattern of infestation by H. comosus in a stand, I settled a study plot of 540 m2 in a P. macrophillus stand in Kagoshima City, and surveyed the infestation of the insect in each standing tree in April and May 2003. Additionally, I determined relative light intensity distribution in the study plot on May 20, 2004. The majority of infested trees occurred near the roadside forest edge, where relative light intensity was significantly high. Diameter at breast height did not differ significantly among intact, damaged, and killed trees. I also conducted laboratory experiments to examine phototaxis of adult H. comosus in May 2001 and 2002. Both male and female adults walked or flew toward the light source, indicating that adult H. comosus has positive phototaxis. From these results, I conclude that the light condition and the adult phototaxis are the important factors for the pattern formation of the spatial distribution of infestation by H. comosus in a stand.

View full abstract

Stable carbon and nitrogen isotopes were studied in a community of a headwater stream covered with old-growth deciduous forest in central Japan, in spring. CPOM (Coarse Particulate Organic Matter), consisting mainly of tree litter such as leaves and twigs, had lower δ¹³C-value than epilithic algae. From comparison of mean δ¹³C-values, finely decomposed tree litter was the main component of FPOM (Fine Particulate Organic Matter). A dual isotope plot of δ¹³C and δ¹⁵N showed that most taxa of benthic invertebrates and fish (char) depended on CPOM and/or FPOM for their C and N source, and only a few taxa of benthos appeared to depend on algae. Therefore, we concluded that the food web in this stream was based on allochthonous organic matter derived from terrestrial forest, rather than on autochthonous production.

View full abstract

Recently, the number of patients with birch pollen pollinosis has increased in Hokkaido, northern Japan. However, little is known about the pollen production and dispersal of birch. We studied the pollen production and dispersal of Betula platyphylla var. japonica and B. ermanii, and the method to evaluate the amount of male inflorescence. The number of male inflorescences (A) and the ratio of flowering branches (B) for 50 cm branches of B. platyphylla street trees were investigated, and the product of A and B were defined as a flowering index. The flowering index was available as a method to evaluate the amount of male inflorescence, because it indicated high positive correlation with the number of male inflorescences per tree. Pollen production rate of B. platyphylla plantation (average height: 19 m) was within the range of 0.07-3.5×10¹² ha^-1yr^-1. When the dominant tree height of B. platyphylla plantation was more than 10 m, the ratio of flowering tree exceeded 50%. The male inflorescence produc-tion of B. platyphylla street trees was affected by pruning for three flowering seasons. B. platyphylla flowered about two weeks earlier than B. ermanii, and the air pollen season of B. platyphylla was earlier than that of B. ermanii.

View full abstract

Seven stands of Chamaecyparis obtusa plantations with different ages, ranging from 20240 years, were investigated to understand their development patterns in relation to the forest practices. Roughly 200-year-old plantations of Chamaecyparis obtusa not only showed larger stem size and stand volume, but also had different species composition and stand structure from plantations less than 100 years old. The old-aged stands developed a multiple layered structure composed of planted trees at the upper layer and broad-leaved trees at the lower layers. These differences in stand structure among old-aged coniferous plantations may be associated with canopy openings caused by logging in the past, as well as the occurrence of standing dead.Therefore, old-aged coniferous plantations need continuous tree density control, even after 100 years, to maintain their vitality as forest ecosystems.

View full abstract

The relationship between the destruction of aggregate structure and changes in soil physical properties such as pore size distribution and permeability after clearcutting was examined. Soil samples were taken from a clearcut area of Japanese cypress (Chamaecyparis obtusa Endl.) 13 years after clearcutting. Soil physical properties were measured and water-stable aggregates were analyzed by the wet-sieving method. After clearcutting, the soil structure changed in A or Al horizons, and the aggregate diameter became smaller with the destruction of aggregate structure. This changed the soil pore composition, namely large pores decreased and fine pores increased, consequently reducing permeability. In A-B horizons, although the soil structures changed, the pore size distributions and permeabil-ity remained unchanged. In B horizons, no changes were found in soil structure, pore size distributions or permeability. In conclusion, in top soil such as A or Al horizons, the changes in soil pore composition and permeability after clearcutting were closely related to the changes in soil structure and destruction of aggregate structure.

View full abstract

A small-scale combined heat and power generator, CHP or co-generation system with gas-engine or micro gas-turbine, which uses gasified wood-biomass and is backed up with the commercial power, is the most probable power-application using wasted bark of about 10 t/day. Locating its gasifier near the lumbermill and the CHP near the customer is the best arrangement in the usual case. Under this arrangement, the gas is transferred from the gasifier to the CHP. When power is supplied to the houses, number of the working generators is adjustable corresponding to the demands because the gas-engine and micro gas-turbine is quickly warm-up and shutdown. Hot water is also deliverable to the houses when the CHP is built near the houses. One generator operated during the working time is the most preferable for a lumbermill. Its power, depending on the transfer efficiency, is estimated to be from 200 to 1, 100 kW. Hot water is supplied to a steam boiler as preheat.

View full abstract

The variation of carboncontent in the stem of 15 individuals representing five plus-tree clones of sugi (Cryptomeria japonica D. Don) was examined. Carbon content in the heartwood was higher than in the sapwood, and tended to be higher in the inner sapwood than in the outer sapwood. Longitudinal variation of carbon content in both heartwood and sapwood tended to decrease with increasing height. Carbon content showed small differences between individuals and between clones, even those of various heights. Carbon contents at 1.2 m above ground level showed significant positive correlation coefficients to the contents at other heights, suggesting that the carbon content of different individuals can be adequately compared by comparing measurements taken solely at this height. Statistically significant differences between clones at this height were found, implying that carbon content in the wood had strong inheritance.

View full abstract

Using cleaved amplified polymorphic sequences (CAPS), which are simple codominant markers, I attempted to identify 74 sugi plus-trees that have been selected to date in Ehime Prefecture. All 74 plus-trees were distinguished from one another using 11 of the 53 markers used.

View full abstract

On a mountainous slope, sap flow velocities in sugi trees (Cryptomeria japonica) located at the ridge and the bottom of the slope were measured using heat pulse sensors. Meteorological factors were also observed at the ridge and the bottom of the slope. Time lag in sap flow velocities was observed between trees at the ridge and the bottom of the slope when transpiration began to occur after sunrise or rainfall. Usually, transpiration occurred earlier at the ridge of the slope than at the bottom. The average value of the time lag was 58.5 min. Additionally, differences in meteorological factors between the ridge and bottom of the slope were observed. The average and variation of the time lag were larger after sunrise than when rain ceased in afternoon. The time lag was highly correlated with differences in both vapor pressure deficit and shortwave radiation between the ridge and the bottom of the slope. Thus, we suspected that differences in both vapor pressure deficit and shortwave radiation between the ridge and the bottom of the slope caused differences in the time lag after sunrise.

View full abstract

It was assumed that stands could control snow cover movements as long as the stands were not be uprooted by the creep and glide pressure of snow and no large movements of snow cover were generated. To determine the stand density that satisfies these conditions, the distances of snow cover movements and the creep and glide pressure of snow were measured in various forests and stands of Cryptomeria japonica D. Don and Fagus crenata Blume were examined. The minimum stand density necessary to prevent uprooting by the creep and glide pressure of snow was determined according to the maximum snow depth and the basal diameter of the Cryptomeria japonica and Fagus crenata, respectively. It was found that more than 400 trees/ha were necessary to prevent large movements of snow cover in the stands assuming that the trees were distributed evenly in the stand. Thus, the stand density to control snow cover movements was represented as values in which both conditions were satisfied.

View full abstract

An improvement in the forest planning information system is a necessary for local forestry management, especially future development of forest GIS. Moreover, there must be an examination of the availability of not just forest planning information, but also existing basic local information for forestry management. This paper focuses on cadastral information, which is a basic type of local landholding information. First, an investigation of the reliability of the parcel number recorded on forest register indicated that certain adjustments were needed in the parcel number recorded on the forest register in order to link forest register with cadastral information. Subsequently, a method of adjusting the parcel number using GIS was devised. These results were used to consider measures would enable cross use of forest GIS and cadastral information.

View full abstract

We investigated the influence of thinning (thinning intensities were 20.5 and 38.5%) on the sheltereffect of inland windbreaks for protecting outdoor activities. Both thinnings were intended to improve the overcrowd-ed condition. The shelter effect was evaluated by the shelter distance at which the wind speed returned to the critical wind speed (which causes initial damage to the protected object) on the leeward side of the windbreak. Wind speeds before and after thinning were measured at a height of 1.5 m. As a result, the shelter effects after 20.5 and 38.5% thinning were evaluated to be the same as or slightly lower before than those thinning when the wind speed on the windward side was less than 2.9 m/s. When the wind speed on the windward side was over 2.9 m/s, the shelter effect covered about 70% of the park next to the windbreak. It was thus found that the shelter effect after thinning to preserve this windbreak was the same as or not much less than that before thinning.

View full abstract

"Symbiosis in the forest ecosystem and its applications in pine forests" supported by BRAIN was discussed with special reference to the puzzle of Tricholoma matsutake. Sequences of the internal transcribed spacer (ITS) region of rDNA were analysed, and a specific PCR primer pair was designed for T. matsutake. This indicates that the presence of T. matsutake can be easily confirmed by the PCR detection. The genetic diversity of T. matsutake was investigated by using PCR-RFLP. Eight IGS1 rDNA types were identified, and type A was by far the most frequent in Japan. Sequences of ITS region among the basidiomata of T. matsutake and T. nauseosum, one of the species closely related to T. matsutake in Europe and North Afrcica, didn't deny their identity. However, whether both species are genetically the same or not should be examined from their interfertility tests (biological species). T. matsutake was elucidated to be a typical ectomycorrhizal fungus by the evidence of Hartig net structure and ATPase activity. Rapid root colonization such as a well-developed Hartig net that appeared in taproots after 2 weeks was established. The rapid mycelial growth was stimulated further by the addition of surfactants. Such a method may contribute to the establishment of T. matsutake Shiro and fruit body formation.

View full abstract