In order to clarify the machining properties of fast-growing trees in Japan, the cutting force were measured during the orthogonal cuttings of the heartwood and sapwood of sugi (Cryptomeria japonica) and five fast-growing tree species, namely koyozan (Cunninghamia lanceolata), sendan (Melia azedarach), two species of eucalyptus (Eucalyptus maidenii and robusta), and yurinoki (Liriodendron tulipifera). The cutting angles and depth of cut were 22°, 32°, 42°, 52°, and 62° and 0.5, 1.0, 1.5, and 2.0 mm, respectively. The quarter-sawn surface was finished by cutting along the grain, whereas the flat-sawn surface was finished by cutting across the grain. When cutting was done along the grain, the parallel cutting force increased with increasing cutting angle and/or depth of cut for all species tested. The parallel cutting force increased with the basic density of the specimen. The cutting forces of yurinoki, koyozan, and sendan, whose basic densities were close to that of sugi, were similar to that of sugi. The normal cutting force increased with increasing depth of cut and/or basic density, however the relationship with the cutting angle was unclear. When cutting was done across the grain, the parallel cutting force increased with increasing cutting angle and/or the depth of cut, but the relationship with the basic density was unclear. The normal cutting force increased with increasing depth of cut, but no dependence on the cutting angle or basic density was observed. No difference was found in the cutting force between the heartwood and sapwood regardless of the species or cutting direction. The difference in the cutting force between the species became smaller with decreasing cutting angle and depth of cut. Thus, we found that fast-growing trees could be cut with a small cutting force by setting a small cutting angle and depth of cut, even if their basic densities were high.

We investigated suspended solid (SS) concentrations, except flooding, before and during line thinning in a Japanese cedar and broad-leaved forested watershed in Ibaraki Prefecture, Japan. Line thinning was conducted at a thinning rate of 35% during 2012 and 2013. Spur roads were constructed along all tributaries (ephemeral streams). The SS concentrations in the regular survey during the thinning conducted in 2012 did not increase significantly compared to the values before conducting thinning. Whereas, SS concentrations were significantly higher during and after the thinning that was conducted in 2013 than the values before conducting thinning. Furthermore, even though 11 hours had passed since the end of the rainfall, high SS concentration (175.4 mg L ⁻¹ ) was observed. This reason may be that the spring water after rainfall eroded the surface of the spur roads and the disturbance by forestry machinery for spur roads construction or timber collection. Therefore, it was concluded that the SS concentrations in streamwater except flooding during thinning might be higher than the values before thinning.

Wood plastic composites (WPCs) have been gaining market share in exterior materials, such as decking, owing to their good decay resisting properties. However, recently, as the domestic exterior market of WPCs has not been showing an increasing trend, the expansion of applications is required. In this study, WPCs with wood percentages of 60% to 75% were exposed to the marine environment to obtain basic knowledge about the WPCs deterioration in marine environments where they have not been used much. In particular, the influences of wood percentages in WPCs on its characteristics changes, such as discoloration, mass change, dimensional change, bending elasticity change, and surface chemical change due to deterioration, were examined. As a result, in the underwater exposure test, almost no feeding damage by marine borers was observed throughout the test period of 21 months, with several percentage levels of mass reduction. Furthermore, the flexural modulus decreased greatly at the early exposure stage as the WPC with higher wood percentages. However, in the splash zone exposure test conducted for 18 months, the WPC surfaces photodegraded and discolored greatly in the early exposure stage. Moreover, the flexural modulus showed a decreasing tendency similar to that in the underwater exposure test. However, the water contact time was shorter in the splash zone exposure test than in the undersea exposure test. Based on the results obtained, the availability of WPCs in the marine environment was discussed.

Estimation of the nutrient accumulation rate in tree biomass is important for understanding the nutrient budgets of forest ecosystems but choosing a suitable method can be challenging. In this study, we compared the nutrient budgets of four forest ecosystems in Japan (Oyasan, Kamigamo, Kiryu, and Takatori) and estimated the nutrient accumulation rates in tree biomass using two methods. For short-term estimates, the nutrient content of tree biomass was measured at two points in time over several years; for long-term estimates, the nutrient content was divided by forest age. The nutrient accumulation rates estimated using the long-term method was lower than those using the short-term method. Weathering rates for potassium, magnesium, and calcium estimated using the long-term method were lower than those using the short-term method. Weathering rates determined using the short-term method were high and could be overestimates in nutrient-limited forests. Soil nitrogen release values were lower with the longterm method than those with the short-term method and could be overestimated when using the latter method in nitrogen-limited watersheds. In conclusion, weathering rates and soil nitrogen release values determined using the long-term method are useful for assessing the sustainability of nutrient cycling in forest ecosystems although the rate of nutrient accumulation in tree biomass is assumed to be constant.

Seasonal occurrences of two mycophagous beetles, Bolbocerosoma nigroplagiatum (Bolboceratidae) and Nothochodaeus maculatus (Ochodaeidae), which are known to feed on the sporocarps of arbuscular mycorrhizal fungi, were observed. We set flight intercept traps on the ground in a Japanese cedar (Cryptomeria japonica) stand in Chiyoda experimental station of Forestry and Forest Products Research Institute, located in Kasumigaura, Ibaraki. Both species was collected from spring to autumn and the collection reached a peak in early summer. On B. nigroplagiatum both male and female were collected similarly in all seasons but on N. maculatus the female was apparently collected more frequently than males. This is the first record for both species collected in the Japanese cedar stand.

The regeneration status of saplings was examined using statistical modeling in a mixed forest in Hokkaido, ten years after small-area scarification under the crown and artificial uprooting were conducted to facilitate regeneration following selection cutting. It was inferred that the effects of both operations on the presence of regenerated saplings were positive; namely, they made the presence probability higher. In addition, a deer-proof fence was considered to have increased the height of the understory vegetation with a probability of 90%. The total effect of the deer-proof fence on the presence of saplings was generally considered to be positive, even when the indirect effect of the fence via understory vegetation was considered. It was suggested that both of the operations, small area scarification under the crown and artificial uprooting, promoted the establishment of Betula maximowicziana.

The capture quantity and species composition of vespine wasps were compared between Malaise traps (MT) and bait (orange juice mixed with liquor) traps (BT) in six secondary broad-leaved tree stands of different ages in central Japan. MTs and BTs captured a total of 99 vespines of 6 species and 918 of 8, respectively, during the spring (May to June) and fall (August to October) collection periods. BTs captured significantly more vespines than MTs in the youngest stand in the spring and in all six stands during the fall period. Proportions of Vespa to Vespula specimens were much larger in BTs than in BTs. Overall, BTs is an effective way to compare vespine species diversity and abundance among different sites, if we use them taking into account its low attractiveness to certain groups including Dolichovespula.

Dung beetles (coprophagous groups of Scarabaeoidea) are useful indicators of habitat quality in tropical regions. To evaluate dung beetle diversity in a variety of land use types, we carried out beetle surveys using pitfall traps baited with human excrement and fish meat from 2004 to 2017 in the Sungai Wain Protection Forest and its surroundings located 10–40 km north of Balikpapan in the lowlands of East Kalimantan, Indonesia. From these surveys, we collected 68 dung beetle species. To help identify these species, we presented photographs and diagnoses of all collected species and included photographs of useful characteristics for discriminating similar species. There is no previously published atlas of dung beetles in Indonesia. Despite only covering a small area on Borneo Island, we hope this atlas will help entomologists and insect lovers in Indonesia identify dung beetles.