Yuki Hirose and Naoto Matsumura: Effectiveness of tree count estimation in Sugi and Hinoki plantations using aerial orthophotos and deep learning. Jpn. J. For. Plann. 59: 1～9, 2025　In this study, we focused on high-resolution aerial orthophoto data, which are being increasingly acquired by local governments, in order to explore efficient methods for obtaining forest resource information in medium- to large-scale regions, particularly with the aim of updating nationwide laser survey data. Using the aerial orthophotos acquired during laser surveys, combined with a deep learning model (EfficientNet) that has demonstrated excellent performance in the field of remote sensing, we estimated the number of standing trees in Sugi (Cryptomeria japonica) and Hinoki (Chamaecyparis obtusa) plantations (15×15m plots). The results showed an overall accuracy of approximately 80%. Notably, the Sugi plantations, due to their distinct crown shapes, maintained high estimation accuracy even in densely populated areas, showing superiority over the hinoki plantations. Additionally, it is expected that applying the proposed method to high-resolution satellite images and past aerial photographs will enable the acquisition of a wider range of spatiotemporal forest resource data.

Naoki Aihara and Yasushi Mitsuda: Automatic forest road extraction using a deep-learning model with a CS topographical map. Jpn. Jpn. J. For. Plann. 59: 11～17, 2025　Utilizing a CS topographical map derived from a Digital Elevation Model (DEM) acquired through airborne laser scanning (ALS), we developed a methodology to automatically extract forest roads using a deep learning model. The deep-learning model, employing a CS topographical map as the input, reproduced 75.1% of the route length for actual forest roads. Of the forest roads extracted by the model, 91.7% were consistent with the existing forest roads. In contrast, the deep-learning model developed using elevation, slope, and plane curvature as inputs could reproduce only 0.1% of the route length for actual forest roads. In forested areas, the automatic extraction of forest roads using conventional photographs is challenging due to vegetation cover. Our forest road detection model can overcome this limitation because it utilizes an ALS-derived DEM as the input. Furthermore, the reproduction rate of forest roads in our model employing the CS topographical map as the input image was significantly higher than that of the model that used elevation, slope, and plane curvature as the input images. This result indicates the efficacy of the CS topographical map for automatic forest road extraction using deep-learning models.

We investigated early survival and growth of advanced regeneration Abies sachalinensis seedlings after clear-cutting of overstory trees in July in stands where many advance growths are not umbrella-like. The two study sites were Okoppe and Mombetsu. 77 % of advanced regeneration seedlings in Okoppe and 55% in Mombetsu remained alive 2 years after clear-cutting. At both sites, seedling height significantly increased after clear-cutting. The results of this study suggest that there would be a case in which the growth of not umbrella-like advanced regeneration A. sachalinensis seedlings can be expected even when overstory trees are clear-cut in summer.

Koji Nakagawa: Zoning of small catchment with special reference to natural landscapes, timber production and biodiversity. Jpn. J. For. Plann. 59: 25～38, 2025　This study focused on ecosystem services, specifically the conservation of natural landscapes, timber production, and habitat provision. By organizing natural and social information following the Montreal Process Criteria and Indicators, the study examined the setting of management objectives, arrangement of forest types, and silvicultural methods. A hierarchical zoning method combining regional and project levels was applied. The following factors were measured: site index, cost, distance, landscape diversity, and visibility. Principal component and cluster analyses were used to characterize the forest types and silvicultural methods. A zoning trial conducted in the Aichi River watershed demonstrated the possibility of setting long-term management goals for small catchment areas at the regional level. At the project level, forest types and silvicultural methods can be flexibly arranged for each stand according to the current socioeconomic conditions of the region. Furthermore, this study showed that even when the management objective is timber production, stands exist where the conservation of natural landscape functions through careful selection of forest types and silvicultural methods is required.