Yasushi Minowa and Keita Asao: Tree species identification based on venation patterns of leaf images photographed with a mobile device in the outdoors. Jpn. J. For. Plann. 53: 43~52, 2020 The aim of this study was to identify tree species based on venation patterns of leaf images,which were photographed with a mobile device in the outdoors. Forty leaves (10 species) collected at the Kyoto University and Kyoto Prefectural University Campus were used as samples in this study. Seven learning patterns were determined from the differences in photography methods and conditions. The venation patterns were evaluated by histograms of oriented gradients (HOG). Two decision-tree algorithms (J48, RandomForest), a lazy learning (IBk) and a neural network (MultilayerPerceptron) were used for machine-learning classification. A performance evaluation of the proposed model was performed with Matthews correlation coefficient (MCC) and correct answer rate. The classification accuracy for test data was verified by the 10-fold cross-validation method. Every learning pattern resulted in classification accuracy for training data; however, the classification accuracy for test data varied greatly according to the difference in learning patterns. By considering camera-tosubject distance, the angle at which subjects were photographed, and the light environment, high classification accuracy could be obtained from the leaf images, which were photographed with a mobile device.
Kosuke Makino, Masaru Oka, Tsuyoshi Kajisa, Yukiyoshi Teramoto, Masami Shiba, Toru Nakajima and Takayuki Nagahama: Calculation of the stem-curve equation of sugi（Cryputomeria japonica ）and analysis of timber quality in the Osumi area of Kagoshima Prefecture: A case study of the Kagoshima University Takakuma Experimental Forest. Jpn. J. For. Plann. 53: 53~62, 2020 At tree-harvesting sites, grading logs are generally made from trees. To maximize the profitability of log operations, wood conversion, which determines the quality grade of logs and timber-yield percentage, largely depends on the adherence to appropriate procedures by forest workers. In this study, we collected data on logs at a production site in real time and assessed their potential applications. Stem-curve equations were developed by measuring trimming length, log length, top end length, and the cutting diameter of each end when the lumber was ready for processing. Next, we analyzed the shape of fallen trees and estimated the timber-yield percentage and quality grade. The timber-yield percentage of cedar wood was consistent with previously documented values in the Osumi area. Furthermore, when the frequency of the quality class was analyzed using the shape ratio as an index, a correlation between the B and C-grade logs and the shape ratio was revealed; however, there was no significant correlation between the shape ratio and A-grade logs.
Masahiko Nakagawa and Naoaki Tashiro: Effect of top soil removal on transition of initial growth of Japanese larch. Jpn. J. For. Plann. 53: 63~68, 2020 Effect of top soil removal on transition of initial growth of Japanese larch, Larix kaempferi, was investigated. Eight years after planting in Higashikagura, tree growth was not significantly different from that in sites prepared by weeding and topsoil removal. Five years after planting in Ashoro, tree growth was the highest with light topsoil removal, followed by that with weeding;the least growth was identified with heavy topsoil removal. The results of this study indicate that initial growth of Japanese larch is not negatively affected or become better by topsoil removal. However, quite heavy topsoil removal may negatively affect growth, likely through thinning of the optimum soil horizon for root systems.
Hiroyuki Kobayashi: Effect of the difference of shooting altitude and DTM products on forest measurement by UAVSfM. Jpn. J. For. Plann. 53: 69~79, 2020 To establish forest measurement method by UAVSfM, aerial photographs were taken over a Sugi (Japanese cedar) stand with a generalpurpose UAV, combining three shooting altitude (80, 100, 120 m) and three DTM (0.5, 5, 10 m mesh) products. Tree top points were decided, tree heights and canopy area were measured and DBH and volume were estimated using SfM and GIS software. The most precise estimation was obtained by the combination of 100 m shooting altitude and 0.5 m mesh DTM product, and number of trees was 86 (ground measurement was 92),average height was 25.29 m (24.81 m) and plot volume was 104.5 m3 (107.6 m3).
Soil of the Tokachi plain of eastern Hokkaido freezes during the winter due to low temperatures and light snowfall. Deciduous and fast-growing Japanese larch, Larix kaempferi, is often planted in arable land windbreaks to prevent wind damage to cultivation plants. Japanese larch is more resistant to winter desiccation than evergreen trees. However,windbreaks made of Japanese larch are disliked by many farmers because they shed a lot of branches and branchlets every year; if not completely removed from cultivation fields, branches and branchlets may damage agricultural tractors. Therefore, some farmers favor planting evergreen trees like Sakhalin spruce, Picea glehnii, or Sakhalin fir, Abies sachalinensis, both indigenous to Hokkaido. However, the disadvantage of these evergreen trees is that they are susceptible to winter desiccation. In settings where spruce and fir do not survive winter desiccation,planting of the evergreen Korean nut pine, Pinus koraiensis, is recommended. Although not native to Hokkaido, this species is less likely to suffer damage from winter desiccation than the other two evergreen species.
In the Tokachi plain of eastern Hokkaido, Japanese larch, Larix kaempferi, is often planted in arable land windbreaks to prevent wind damage to sugar beets,potatoes, and beans during the spring cultivation season. Japanese larch is fast-growing and very effective in reducing wind damage in the early spring cultivation season, even if its buds are not open or its leaves are not fully extended. However, many farmers dislike Japanese larch arable land windbreaks because they shed a lot of branches and branchlets to cultivation fields every year, which may cause damage to agricultural tractors. Therefore, it is necessary to suggest a model of arable land windbreaks with less amount of fallen branches and branchlets of larches entering the cultivation field. It is recommended to plant three rows of trees: Japanese larch in the most windward and middle rows, and Japanese white birch, Betula platyphyllavar. japonica, in the most leeward row. Japanese larch in the most windward and middle rows reduces wind speed, whereas Japanese white birch in the most leeward row reduces branches and branchlets of Japanese larch entering cultivation fields.