We estimated the indirect effects of an over-abundant deer population on carabid beetles in the Tanzawa Mountains by comparing their community from five sites with different levels of damages to vegetation. We also sampled carabids from in- and outside of three 8-years-old deer exclosures to assess the effectiveness of these fences on carabid conservation. The mass of forest-floor vegetation had a negative effect on the number of the most-abundant species, Pterostichus yoritomus, and a positive one on that of the species with the largest body size, Carabus (Leptcarabus) procerulus, as was demonstrated by Poisson regression and model selection. This result was compatible with a general trend that decline of vegetation cover affects small carabids positively and large carabids negatively. A prominent effect of vegetation mass was also suggested from a redundancy analysis targeting five dominant carabid species. These results showed the strong indirect effect of over-abundant deer populations on carabid communities. Lots of C. procerulus were captured from inside deer exclosures, which had been installed before vegetation was heavily damaged, suggesting their effectiveness in the preservation of large-bodied carabids.

In recent years, airborne LiDAR has been proposed as a means to acquire accurate information regarding forest structure. However, while measurements, such as tree height and crown size, can be obtained directly using airborne LiDAR, mathematical equations must be used to indirectly estimate stem volume and diameter at breast height. The equation parameters vary with tree species, so it is important to obtain accurate tree species information for each tree species to estimate accurate forest information. In this study, we propose a method for classifying tree species with high precision in single tree units using airborne LiDAR intensity data and LiDAR structure metrics. Five tree species were included: Japanese cedar, Japanese cypress, red pine, larch, and broad-leaf (deciduous and evergreen) species. We used LiDAR intensity data and tree crown shape metrics to calculate eight tree feature quantities and then compared the measurements among the five tree species to evaluate the importance of feature quantities. The comparison was performed using the random forest machine learning algorithm. We found that crown shape calculated for a grid unit of 10 m×10 m was more effective for classification than those of single trees. Classification accuracy of 93.7％ was recorded after classifying the above five tree species using the proposed eight feature quantities. Thus, it is possible to accurately classify single tree units using the feature measurements presented in this study.

We investigated how competition with weeds affects survival and height growth of Japanese larch （Larix kaempferi） seedlings in three consecutive years after planting. We planted three types of nursery stock, two-years and three-years-old bareroot and one-year-old containerized seedlings, with different height to examine the effect of initial seedling height on the competition with weeds. The tallest three-year-old bare-root seedlings showed less suppression by weeds in all three years, whereas the shortest containerized seedlings experienced much suppression. In the first year, when weeding was conducted, the degree of competition had no effect on survival rate; height growth was decreased only when weeds covered the entire seedling crown. In the second and third years, when weeding was not conducted, survival rate and height growth were significantly decreased when at least 75 and 50％ of the seedling crown was covered by weeds, respectively. It was estimated that the seedling height will be 91-100 cm shorter three years after planting if more than 75％ of the crown is covered by weeds. These results suggest that Japanese larch seedlings are susceptible to suppression by weeds, and, thus, weeding should be conducted to hold the crown cover by weeds below 75％. Planting taller seedlings would be effective for reducing weeding cost in Japanese larch.

We evaluated the conditions necessary for the establishment of an avalanche protection forest on a steep slope mounted with wooden anti-glide tripod structures under 2 m of annual maximum snow depth. We investigated five forest stands on slopes of 35° with 450 tripods/ha or 40° with 620 tripods/ha, more than 7 years after the construction of the tripods and planting of sugi (Cryptomeria japonica) seedlings (planting density of 1,020-2,500 seedlings/ha). Survival rates of the tripods decreased to ca. 80 and 40％ after 9 and 12 years, respectively. In contrast, height growth of sugi trees could be termed a middle site quality. In addition, under planting density of 2,500 seedlings/ha, which is a common regime for afforestation, stand densities of erect sugi trees, which had grown up to twice the annual maximum snow depth, were estimated to be 1,000 and 1,500 trees/ha after 9 and 12 years, respectively. It is considered that snow cover can be stabilized in more than 1,000 trees/ha of erect sugi. Thus, these results suggested that, for avalanche protection, sugi forests can be successfully established with wooden tripods on a steep slope, and with planting density above a certain level, under 2 m of annual maximum snow depth.

The information of snow environment is very important for a study of forest or making a judgment of forest management method. “Mesh normal climatic data 2010” shows the distribution of average annual maximum snow depth. But then, the estimate values of maximum snow depth are underestimation compared to the observation values of that in high elevation area. On the other hand, at low temperatures, the amount of precipitation in the form of snowfall increases, and the melting of snow is less likely to occur. Thus, the maximum snow depth is observed increase further. Therefore, we developed a model for estimating the average annual maximum snow depth based on the estimated distribution of the mean temperature and precipitation values of “Mesh normal climatic data 2010”. We further demonstrated that the proposed model is accurate enough for reproducing the observed values.

To clarify the effects of Chinese fir (Cunninghamia lanceolata) on surface soil movements we measured the transport of materials on a range of sloping forest stands and compared our findings with those of related studies using a simple transport rate (g m⁻¹mm⁻¹) as the indicator of soil erosion. We placed sediment traps at the site to analyze the following factors: gradient, material type and time period. At the site, transport rates of steeper slope were larger than those of gentler slope. However, the magnitude of transport rates was small. The possible reason was high litter coverage rate even on the steeper slope. Compared with other tree species, the Chinese fir stand has the same material transport rates as that of mixed stands of Japanese red pine (Pinus densiflora) and broad-leaved trees, which are also said to have high surface soil conservation.

Mass propagation of pine wood nematodes (PWNs) has generally been conducted using Petri dishes containing 20 g barley. However, this method is labor intensive, especially when a large population of PWNs is required, thus hindering the work involved in their propagation. In this study, we determined the utility of mushroom bed cultivation bags, with a capacity for a large amount of barley, for the mass propagation of PWNs. We used 100 Petri dishes and 6 cultivation bags with 2,000 and 1,700 g barley, respectively, for propagating PWNs. Sufficient and comparable numbers of PWNs were obtained from Petri dishes and cultivation bags. However, the operation time required for the propagation of PWNs varied from 407 minutes using Petri dishes to 76 minutes using cultivation bags. Thus, the operation time involved in propagating PWNs using cultivation bags was only 20％ of that involved in PWN propagation using Petri dishes. On the basis of these data, we conclude that the propagation of PWNs can be greatly improved with the use of cultivation bags.

Evergreen broadleaved tree seedlings are recently planted to maintain the function of coastal protection forest after pine wilt disease in the former pine stands on the coastal sand dunes. Those seedlings, however, have a problem of poor vigor in the early rooting stage. On March 2014, both evergreen broadleaved tree species of Neolitsea sericea and Machilus thunbergii were planted in a coastal pine forest where pine wilt disease has been proceeding and deciduous broadleaved trees have naturally been invading. This study examined the effect of light intensity, soil temperature and soil moisture that measured in summer on the survival of the two species. The residual pine and invaded tree canopies played a significant role as a nurse plant for the survival of the young seedlings. In addition, Neolitsea sericea and Machilus thunbergii were significantly influenced by light intensity and soil moisture, respectively. We concluded that sparse canopies should be retained to facilitate planting evergreen broadleaved seedlings in a coastal protection forests.