Ten years after group cutting to promote regeneration of broad-leaved tree species, we investigated litterfall and the organic horizon (O-horizon) at three different slope positions in a secondary hinoki cypress-dominated forest. The aim was to determine the effects of the cutting on nitrogen (N) cycling. In the cut plots on the middle and lower slopes, where abundant tall broad-leaved tree species had regenerated, carbon (C) and N inputs by leaflitter from these trees were higher, and the litterfall C/N ratio was lower, than in the control plots. In contrast, on the upper slope, where abundant woody shrubs had regenerated, these parameters did not differ between the control and cut plots. Litterfall C/N ratio decreased with increasing N input by leaf litter from broad-leaved species. Stocks and mean residence times (MRTs) of C and N in the O-horizon were lower in the cut plots than in control plots at the same positions. The MRTs of C and N in the O-horizon decreased as the litterfall C/N ratio decreased. The decrease in MRTs in the O-horizon in the cut plots was much greater at the middle and lower slope positions than at the upper position. These results suggest that the change in MRTs in the O-horizon at each position 10 years after group cutting is strongly influenced by the type of tree species that regenerates in the cut plots, but not by differences in soil nutrition along the slope.

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A simple method for precisely estimating leaf biomass is required in forest ecosystems. Strong correlation has been reported between leaf biomass and basal area at the crown-base height of a tree (A_B), suggesting the pipe model theory is applicable. Basal area at the crown-base height can also be estimated from tree height (H), crown-base height (H_B), and basal area at breast height (A_1.3). A simple method for estimating leaf biomass was developed using the relationship between these measurements and was applied to three hinoki cypress forests in Kochi prefecture. When A_B was estimated from A_1.3[(H－H_B)/(H－1.3)], the slope of the regression equation was approximately one and the intercept did not differ between the three forests. When leaf biomass was estimated from A_1.3 or A_1.3H, the slope or intercept of the regression lines differed between the three forests. When leaf biomass was estimated from A_B or A_1.3[(H－H_B)/(H－1.3)], the slope of the regression was approximately one but the intercept differed between the three forests. These results suggest that leaf biomass per unit of basal area at the crown base height is constant in an area, which supports the pipe model theory. Leaf biomass per unit of basal area at the crown base height in six regions including previous results was positively correlated with mean annual temperature.

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To examine changes in the wood species and in the manufacturing and distribution of wooden baseball bats (henceforth bat) in Japan, we interviewed managers at six major domestic bat factories and conducted a literature review. In 1979, almost all bats manufactured domestically were made of Japanese ash (Fraxinus lanuginosa) in Hokkaido. However, around 2005, manufacturers began using North American and Chinese maple (Acer sp.) and Chinese moso bamboo (Phyllostachys edulis). Currently, at least 70% of the bats manufactured domestically are made of imported woods. We found three major changes in the distribution. First, the number of bat material factories in Hokkaido has decreased sharply. Second, there is a clear divide between manufacturers who remain as subcontracting factories and those who do not. Third, whereas bats were processed and manufactured in Japan in 1985, today overseas processing is popular, and some are manufactured in China. In addition, the online sale of bats has become popular. To continue the manufacture of F. lanuginosa bats in Hokkaido, it is necessary not only to protect and grow F. lanuginosa but also to indicate the country of origin on bats.

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Two methods are commonly used to measure the diameter of a tree’s crown or to make tree crown projection figures. One is to measure between points transcribed by eye from the ends of the tree’s branches to the ground below the tree; the other is based on aerial photographs. However, the accuracy and precision of these methods can vary by tens to hundreds of centimeters, as it is difficult to determine the precise locations of these points by eye or from photographs. To address this issue, we developed a new tree crown measurement tool, the Ten-bou-kyou, roughly translated as vertical mirror-eye to the sky. To assess the tool’s accuracy and precision, we used it to measure branch like marks beyond our reach 100 times and compared the results with known reference data. The results using our device differed from the reference data by -1 to 4 cm, with an average of 1.8 ± 1.0 cm. Therefore, we conclude that, despite its slight positive bias, the Ten-bou-kyou may be a promising method for determining the location of points directly below tree branches to within approximately ± 1.0 cm.

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