We carried out a feasibility test using odor of a thiazoline compound that induces the innate fear reaction of mice, aiming to develop a new sika deer repellent in young conifer plantations. It has revealed that predator-originated thiazoline compounds invoke a fear reaction in mice in a laboratory and the reaction is determined genetically. We examined whether 2-(Methylthio)-2-thiazoline (C ₄ H ₇ NS ₂ , hereafter 2MT2T) would inhibit the foraging behavior of captive sika deer (Cervus nippon). At first, we confirmed that a self-build volatilizer showed a volatilization rate of approximately 100 mg/h, and we monitored the odor-spreading process with an odor meter. Secondarily, automatic video cameras recorded the foraging behavior of captive sika deer to Japanese knotweed (Fallopia japonica var. japonica) fresh leaves beside the two volatilizers with 2-ml 2MT2T. We recognized only four times of avoidance behavior amid 1,590 times of foraging behavior, and the sika deer ate up knotweed leaves within 15 h after the beginning of the trials. It can be hard to expect the repellent effect of 2MT2T against sika deer in an open field to invoke avoidance behavior or to control foraging behavior.

The present study examined seven years of birch regeneration after clearcutting the fir, Abies sachalinensis, plantation, and scarification treatment in the Eniwa National Forest, Hokkaido. The clearcutting and scarification treatment was conducted in 2016. The test had four settings based on the combination of the presence/absence of scarification treatment and a deer-proof fence, which surrounded a part of the plot. Regeneration of tree species, including birches, was examined in 2018, 2019, 2021, and 2023. The cover and average stand height of the dwarf bamboo, Sasa senanensis, which competes with the tree species, were also measured. Results indicated that the cover of S. senanensis reached nearly 100% except in the scarified area outside the fence, and the average stand height recovered to approximately 80–110 cm. Prominent differences were found in the sapling density and the height of birches between inside and outside the deer-proof fence. Inside the fence, the sapling density tended to be larger in the scarified area than in the control area. In 2023, seven years after the treatment, the density of the birch saplings higher than 150 cm reached 18,000 / ha in the scarified area in the fence. All of the saplings outside the fence were less than 150 cm tall. These results showed that the scarification treatment after clearcutting the fir plantation was effective for the natural regeneration of birches.

The timbers as structural members in traditional Japanese wooden buildings provide important information at the time of construction such as the cultural and historical background. The main hall of Jyosho-ji Temple in Onomichi City, Hiroshima Prefecture (National Important Cultural Property), one of these traditional Japanese wooden structures, was built approximately 500 years ago, and its structural members have been used as they were when the temple was built. We conducted an investigation of 127 removed timbers considered no longer useful as structural members during the restoration of the main hall of Jyosho-ji Temple. The wood species, apparent density and annual ring width of each of these removed timbers were investigated, and cross-sectional photographs and optical micrographs of the three sections (transverse, radial, and tangential sections) of these removed timbers were taken.Of the 127 pieces examined, 118 were JI-DARUKI, 5 were TOSHI-HIJIKI, and 4 were HIEN-DARUKI. All the pieces were assumed damaged by Anobiidae. The results of wood species identification using optical micrographs showed that 119 of the 127 removed timbers were Japanese red pine (Pinus densiflora Sieb. et Zucc.) and the remaining 8 removed timbers were Japanese cypress (Chamaecyparis obtusa (Sieb. et Zucc.) Endl.). The apparent density of these removed timbers was similar to or higher than that of commonly distributed timbers of Japanese red pine and cypress. The mean annual ring width of the removed timbers was slightly wider in the red pine and almost the same for cypress compared to commonly distributed timbers. Among the Japanese red pine timbers, 55% were without pith, whereas most of the Japanese cypress timbers contained pith. An examination of the positions of the removed timbers in the main hall revealed that they were mostly located on the western and northern sides.

Severe withering was observed on cedar-cutting varieties from Kyushu in a 4-year planting site in central Shikoku. Overall, 66 saplings out of 112 of the high-performing variety “Takaoka#1” showed dead foliage and stem, including individual deaths on a north-facing slope at 900 m above sea level. The proportion of saplings with dead parts was higher compared to the conventional variety “Tanoaka,” which showed five damaged saplings out of 109. The deadly damage to Takaoka#1 was suspected to be mainly caused by late and early frosts, as sudden air temperature drops were recorded in early spring and winter in 2023. Cold injury was not found on the stems, and the damage did not worsen in the mid-winter. Takaoka#1 might be more sensitive to cold temperatures than Tanoaka, thus requiring careful selection of planting sites.