Katsuto Shimizu: stemv: An R package for calculating tree stem volume in Japan. Jpn. J. For. Plann. 58: 55～60, 2024　Calculating stem volume is important for forest resource management and research analysis. In Japan, stem volume tables and equations for main species have been developed; however, it requires considerable effort for users to extract the corresponding equations and perform relevant corrections. This article describes the features of an R package developed for calculating stem volume in Japan and compares the calculation results against the existing calculation program. The advantages of calculation in the R environment are also discussed. Stem volume calculation using diameter at breast height and tree height was based on 83 equations established by the Forestry Agency in Japan and corrected by methods proposed by Hosoda et al. (2010). The comparison using simulated data revealed discrepancies in seven equations; however, the calculation results generally aligned with the output from the existing calculation program, with only 0.19% of the total data showing a difference greater than 0.01m³. The processing, using national forest inventory data, suggested that computation time is acceptable for data analysis. The stem volume calculation in R would contribute to more transparent and reproducible data analysis in the open-source environment.

Masaru Watanabe, Masashi Saito and Keisuke Toyama: Application of Forest Zoning Based on Forestry Profitability and Landslide susceptibility on a Wide Area. Jpn. J. For. Plann. 58: 83～91, 2024　In recent years, the importance of multi-purpose forest management, including timber production promotion and landslide susceptibility management, has been increasing due to the aging of planted forests and the progression of climate change. In order to make policy decisions regarding future forest management and domestic timber supply, it is necessary to quantitatively understand what kind of land has what kind of potential in terms of two criteria: material production and landslide susceptibility. In this study, the zoning based on profitability and landslide susceptibility was applied to planted forests in private forests in Gifu Prefecture, and the area ratio of each zone was clarified. The results showed that the zones of cautionary forestry land (high profitability, high susceptibility), suitable forestry land (high profitability, low susceptibility), potential forestry land (low profitability, low susceptibility), and unsuitable forestry land (low profitability, high susceptibility) accounted for 10%, 29%, 31%, and 29% of the total area in the entire prefecture, respectively. Furthermore, the score structure of each criterion was examined for each zone. It was suggested that by looking in detail at the combination of high and low scores for the same zone, management policies with higher resolution and tailored to specific potentials could be proposed.