In 2009, mass mortality caused by Japanese oak wilt was confirmed in a Quercus serrata secondary forest at Shimane University. In a 1 ha study area within the forest, we investigated Q. serrata stem diameter, mortality, and survivorship from 2001 to 2018, and the distribution of dead oak trees from 2012 to 2014. Although the total basal area of stems had been increasing before the occurrence of Japanese oak wilt, the area decreased continuously until 2018 after the infection occurred. Many small oak trees had died before the outbreak, while the disease killed various sized trees in 2012 and 2013 and killed small ones in 2014 when it spread. Moreover, the trees killed by the disease were in the valley. The numbers of dead trees found in 2013 and 2014 were similar to those found during the 5 years prior to disease occurrence. During the 17-year study period, the mortality rate due to Japanese oak wilt was 18.1％, whereas that due to other factors was 32.2％. We predict that this mass mortality event will alter the structure of this secondary forest, due to the rapid death of various sized trees, including large ones.
Leaf area is an essential parameter for quantifying physiological traits such as photosynthesis. Sugi (Cryptomeria japonica D. Don), a coniferous evergreen, is widely planted in Japan. It is laborious to directly measure needle projected area (An) of Sugi, because there is a need to detach each needle from a shoot. The objective of this study is to elucidate whether An can be estimated from shoot projected area (As) which is relatively easily measured by using a scanner. We investigated the effects of canopy position and leaf age on the An‒As relationship and also compared three different varieties of Sugi. As a result, An was strongly correlated with As and there were no significant effects of canopy position, leaf age in months, or varieties on the An‒As relationship. Moreover, a relationship between needle mass per An (LMAn) and shoot mass per As (LMAs) showed the same results as the An‒As relationship. These results suggest that, once these relationships are established by shoot sampling in a given month for a target variety, needle projected area and LMAn can be estimated from measurements of shoot projected area and dry weight of the shoot. Furthermore, a common equation might be established irrespective of varieties of Sugi. However, inter-varieties variation in An‒As relationship should be further verified.
The objective of this study was to investigate the utility of Landsat time series data for the detection of harvested area using annual data on the main island of Kyushu. We used a change detection algorithm to extract variables for the classification of harvesting, other disturbance, stable forest, and other land cover change. The estimated annual harvested area from 1985 to 2017 was 7426.5 ha, on average, with an increasing trend in the last decade. The overall, producer’s, and user’s accuracies were 95.2％ (±0.5％), 83.1％ (±2.9％), and 93.8％ (±0.9％), respectively, based on the accuracy assessment using satellite images. When the accuracy was assessed based on ground survey data, 87.6％ of the harvested area was detected by annual Landsat time series data. When the accuracy was assessed based on statistical data, the estimated harvested area was 2.6％ larger than the recorded clearcut area in national forests and 30.5％ larger than the recorded clearcut area in private conifer forests in Miyazaki Prefecture. This study demonstrated that using annual Landsat time series data is a viable approach for the detection of harvesting in a large area across several decades.
In Japan, the origin of the forest planning system can be traced back to two events which made a major impact-namely, the 1939 amendment of the Forest Law and the formulation of the forest policy during the Allied occupation of Japan under the General Headquarters/Supreme Commander of the Allied Powers (GHQ/SCAP). My research involved the analysis of the present forest planning system as well as the discourse of policymakers involved in it. It can be concluded that the 1939 amendment to the Forest Law extended the scope of the forest management plan to private forests as well, and was the basis for the current forest planning system which includes technical mechanisms such as forest registers. At the same time, the evaluation of the 1939 amendment of the Forest Law is a point of contention among policymakers, especially with regards to the wartime regime. For this reason, the significance of the 1939 amendment of the Forest Law may have been underestimated after World War II. With regard to the policy under the Allied occupation, the “forestry program” as given in the GHQ/SCAP document provided an accidental opportunity for the formulation of a forest planning system. Revisiting the discourse of policymakers of that period, it can be inferred that as a result of political horse-trading with the occupation policy, the forest planning system formulated at that time laid the foundation of forest policy in Japan after the war.
We analyzed the mortality factor and spatial distribution of trees in a sedimentation-dominated riparian forest in a warm-temperate mountainous region by using the monitoring data of 7 years, forest dynamics with a special focus on suppression. Based on the results, we discussed a part of a coexistence mechanism of coppice woodland species and aestatilignosa forest species (CA species) with five major evergreen broadleaved species within the same geomorphic unit. A generalized linear model (GLM) of survival rate detected overstory stem density as a significant explanatory variable for the CA species and the major evergreen broadleaved species, except for Persea japonica. The CA species showed the lowest survival rate, indicating remarkably lower shade tolerance than that of the evergreen broadleaved species. Among the major evergreen broadleaved species, Quercus gilva demonstrated relatively lower shade tolerance than the other species. The CA species tend to be distributed on sites close to the channel. Q. gilva had a significant distribution bias toward the sites derived from large-scale disturbance. These results suggested that frequent but less intensive disturbances might provide constantly better light environment by restricting establishments of evergreen broadleaved trees, which allows the coexistence of CA species with evergreen broadleaved species. Among the major evergreen broadleaved species, Q. gilva seemed to depend partially on large-scale gaps for its coexistence with other evergreen species.
This study identified the cost-effective weeding schedules for reducing weeding cost. First, we used a Monte Carlo method to simulate 7-year-old sugi (Cryptomeria Japonica) mean height and cumulative weeding operation time under different combinations of weeding timing and frequency from 0 to 6 times after planting. Then, we calculated operation time per sugi mean height to express cost-effectiveness. Moreover, to evaluate the stability of the cost-effectiveness, we calculated coefficient of variation for sugi mean height, cumulative operation time and operation time per sugi height. Each coefficient of variation was lower when weeding frequency was equal to or more than three times. The operation time per sugi height decreased when weeding was conducted in the first or second year after planting. We conclude that the three-treatment weeding frequency including the first- or second-year weeding is more effective weeding for the reduction of weeding costs.
Passalora needle blight caused by Passalora sequaoiae is one of the serious disease in the nursery of Japanese cedar (Cryptomeria japonica). It was epidemic in the early 1900s and during the period of expansion reforestation in the around 1950, and caused devastating damage to nursery production of Japanese cedar. At present, the damage of this disease has not become a serious problem, but this disease is by no means a past disease. If it is not properly controlled, it still causes damage to nursery of Japanese cedar. Whereas, it is also true that with accurate knowledge on this disease, the damage caused by this disease could be almost completely controlled. With the recent increase in production of cedar saplings for re-afforestation, it is concerned that this disease will be prevail. The damage of this disease has already occurred in several areas, and this may also occur in containerized seedlings recently developed in Japan. The purpose of this review is to compile the knowledge of this disease that is likely to be damaged again in the near future, to understand of this disease, and to organize the further issues.
The purpose of this study was to propose teaching content on the subjects of forest science, forestry management, and usage of forest products in high schools according to the Ministry’s official guidelines for school education in 1999, 2009 and 2018. We classified the contents of a technical book on forestry and forest products, and the areas of content from the viewpoint of the subject content studies of “the technology of nurturing living things” in technology education. We found a clear relationship between forests and societies and identified some overlap among the three subjects from 2009. The practice of forest science, the practice of forestry management, and the practice of usage of forest products were placed together as a session about problem-solving activities according to Ministry’s 2018 guidelines. On the others hand, though nursery practices and breeding had been described in a chapter of the technical book and categorize according to the early stage of cultivation, they had been eliminated from the teaching content of forest science in 2018.
Various studies have examined the effectiveness of Nature Experience Activities. In this one, we examined the influence of Ikiru Chikara and Symbiotic Values with Nature on children participating in Nature Experience Activities in a forest environment. This research focused on the characteristics of participants and examined the effect of the program in terms of the impact of the original nature experiences and the mental and physical trauma of adverse experiences of natural disasters. The subjects analyzed were 213 participants in Fukushima Kids Program and their parents, all of whom were asked to provide feedback via questionnaires on aspects of Ikiru Chikara, Symbiotic Values with Nature, nature experiences and the experiences of parents during the disaster. After analyzing Symbiotic Values with Nature, the three factors emerging included an affinity with nature, relationship between nature and life and interest in and consideration of nature. The analysis of all participants showed that the program improved both Ikiru Chikara and Symbiotic Values with Nature. This improvement was clear following a comparison made with children with less experience of nature. What also emerged was how the occurrence or absence of a fearful experience caused by on earthquake affected on the level of physical ability.
To promote forest education in formal schooling, we studied the methodology to continuously reflect forest experience activities to in-class learning. This was done through forest learning units in an elementary school. We conducted surveys twice, once each in the fiscal years 2015 and 2016, for a fifth-grade unit that included forest experience activities. This unit consisted of five phases: 1) forest experience activities at the Fuji Iyashinomori Woodland Study Center, The University of Tokyo Forest; 2) a class using video learning tools to review the activities of the first phase; 3) advice about the children’s investigative learning from graduate students; 4) intermediate presentations of the children’s investigative learning; and 5) final presentations of their investigative learning. We then did co-occurrence network analysis and cluster analysis on words extracted by morphological analysis from sentences used by the children to describe what they had learned after phases 2) and 5). As a result, the validity to present the children with video learning tools for reviewing their forest experience activities through their five senses starting with smell and hearing was suggested.
This study examines the implementation status of the “Tree Expert Program for Children” (Kodomo-jyumoku-hakase) being held in various parts of Japan by an evaluation axis based on school-age to clarify its progress. We conducted a questionnaire survey to 242 implementing entities. The results show that the implementation trends throughout Japan are aimed mainly at sparking interest in children and increasing their familiarity with the different types of trees and are a standard part of each implementing entity’s project. Many organizations used familiar trees, such as a characteristic tree species in the park and representative tree species in the area. Therefore, it is difficult to connect directly to larger forests, and further consideration is required. The staff of particular implementing entities often teach about the trees and participants were divided into about ten people per group. Twenty different tree species were described, and the program often lasted about 90 min. On the other hand, some implementers described more than 50 different tree species. Effective implementation for school-age needs to deal with such factors as the number of tree species and implementation time, accounting for the developmental stage of the participants.