Papers - UEHARA Iwao
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Iwao UEHARA
Kanto Journal of Forest Research 76 ( 1 ) 29 - 32 2025.03
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：関東森林学会
要旨：2011年3月の東日本大震災の発生以来，福島県内の各地にはいまなお放置された状態の山林が数多く存在している。本論文では，放射性降下物の汚染が甚大であった地域の一つである相馬地方のスギ，ヒノキの放置林および広葉樹二次林を対象地とし，それぞれ間伐をおこない，その後の植生回復を観察し,今後の当地における施業について提言することを目的とした。研究の方法は，各調査林分において50％の本数間伐を2019年～2022年に実施し，間伐前後の相対照度を比較し，それぞれ10 ｍ×10 m（１a）の調査区を4か所ずつ設けて，2024年6～10月に植生調査をおこなった。各林分では30～50樹種前後の実生が見出されたものの，その上長成長は低く，スギ，ヒノキ林分においては林床の被覆度も低かった。その主な理由には林冠閉鎖による低照度が推察され，追加の間伐が必要と考えられた。
キーワード：相対照度，林床植生，被覆度，実生，50％間伐
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Effects of leaf allelopathy on plant seedling growth of forest trees. Reviewed
Mai MARUYAMA, Megumi TANAKA, Iwao UEHARA
Kanto Journal of Forest Research 76 ( 1 ) 77 - 80 2025.03
Authorship：Corresponding author Language：Japanese Publishing type：Research paper (scientific journal)
Abstract: The plants have been reported to have allelopathic effects that inhibit or promote the growth of other plants. Although it is known that there are several pathways for their expression, such as volatilization and dissolution, few studies have focused on the allelopathic effects of trees, and also few have been able to identify the allelopathic substances. This study aimed to investigate the inclination and factors of allelopathic effects at six forest tree species, and to accumulate basic data. Growth indicators of lettuce
seedlings due to volatilization and leached components were measured. The results showed that although growth suppression was observed overall, there were no differences among species. The difference between fresh and defoliated leaves also differed among tree species. The growth inhibition in the Sandwich method may be due to the action of relatively stable substances.
Keywords: Allelopathy, Sandwich method, Dish pack method, Forest tree
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Shoko TODA, Megumi TANAKA, Iwao UEHARA
Kanto Journal of Forest Research 76 ( 1 ) 57 - 60 2025.03
Authorship：Corresponding author Language：Japanese Publishing type：Research paper (scientific journal)
Abstract: Main of cutting is that insert into the soil, but there is a method wood scion in the water that insert into the water. Wood scion in the water seems to be used for plants that root when they in the water, but due to insufficient oxygen supply, it is reported that delay root development and cause soft roots. When we grow wood scion in the water, we have to stabilize the cuttings. In this study, we use Morus australis, which had shown rooting by wood scion in the water in a previous study, was used to prepare and grow two types of plants, one inserted in Kanuma soil and the other in three different types of wood scion in the water. Survival rate and growth rates were higher for those inserted into the Kanuma soil than into water. Survival rates were improved by creating space around the cuttings bases in wood scions in the water. Since the amount of growth is by far the highest for those inserted in soil, it is considered necessary to circulate air, etc. in the case of wood scion in the water.
Keywords: wood scion in the water, Morus australis, rootage, survival rate, cutting media
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Utilizing local forests for local elderly people: Case studies and their future possibilities Invited
Iwao UEHARA
Proceedings of 1st Challenges and Tasks in the Era of Super-Aging : Forest Therapy and Well Aging International conference 1 ( 1 ) 197 - 204 2024.10
Authorship：Lead author Language：English Publishing type：Research paper (international conference proceedings) Publisher：Dongguk University, Korea
Currently, aging in local communities is a major social issue in Japan. At the same time, the increase in abandoned forests in various regions is also a major issue. However, if the health and recreation functions of forests can be effectively utilized, local forests have great potential for promoting the health of local elderly people, preventing diseases, and improving their health.
This paper introduces five case studies of health and recreation in local forests in local communities in Japan. The first two cases are from Fukuoka Prefecture and Kagoshima Prefecture in Kyushu, which are close to Korea. At local hospitals in both prefectures, forests of cedar, cypress, and evergreen broadleaf trees that had been abandoned were developed and used mainly for the treatment of dementia patients.
As a result, the patients' behavioral disorders associated with dementia (BPSD) decreased, and improvements were seen in their daily lives. The next case is from Saitama Prefecture and Nagano Prefecture in Honshu. Reg
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Iwao UEHARA
森林保健研究 5 1 - 5 2024.08
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：日本森林保健学会
This paper shows a case where a hospital-owned secondary forest of broad-leaved trees, which had been abandoned for more than 30 years, was developed for patients’ rehabilitation and recreation at a regional hospital in Tokyo. The survey site is Ongata Hospital and its forest (approximately 6 ha) located in suburb of Hachioji City. The owned forest is mainly a secondary forest of broad-leaved trees. The tree layer consists of trees such as Quercus serrata, Q. acutissima, and Castanea crenata, as well as Zelkova serrata, Celtis sinensis, and Magnolia ovobata. The forest floor is thriving with Sasamorpha borealis. As of September 2020, the tree density before maintenance was around 4,000 to 6,000 trees per a ha, and the average relative light intensity in the forest was around 5 %.Clearing and thinning work on this forest block began in October 2020 and continued until September 2022. The tree density decreases to 1,500 trees/ha in 2021 and to 300 to 500 trees per a ha in 2022. The average relative illuminance improved to around 15 to 30 %. The number of confirmed tree species on the forest floor was around 40. The thinned wood was used to create rest benches, walking paths and occupational therapy of patients.
Key-words: secondary forest, thinning, Sasamorpha borealis, forest therapy, Hachioji City
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Attempts of forest therapy at Nishino Hospital in Kita-Kyushu city, Japan Reviewed
Iwao UEHARA
森林保健研究 5 6 - 18 2024.08
Authorship：Lead author Language：English Publisher：日本森林保健学会
An aging society is currently a feature of our country, and health promotion for the elderly has also become an issue. Many elderly people suffer from some kind of disease or poor physical condition, feel anxious about their health, and it is not uncommon for elderly people to spend the rest of their lives in social welfare facilities. Under these circumstances, this report shows a case in which a local hospital and social welfare facility have several hectares of forest on their premises, and are using it for health and respite for patients and users.
Keywords: local hospital, social welfare facility, health promotion
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Iwao UEHARA
Kanto Journal of Forest Research 75 ( 1 ) 25 - 28 2024.03
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：関東森林学会
Abstract: In this study, I thinned an artificial cypress forest in Minamisoma City, Fukushima Prefecture, and conducted a subsequent vegetation survey. The survey targets were a forest stand that is approximately 30 years old and has never been thinned
or pruned (Haramachi district), and a young forest that is approximately 20 years old and has been pruned once 10 years after planting (Odaka district). There are 2 locations. The former had a stand density of 3500 trees/ha, average tree height 12 m, and average DBH 15 cm, while the latter had a stand density of 2000 trees/ha, average tree height 8 m, and average DBH 12 cm. The former cypress forest was thinned by 50% in December 2021, and the latter cypress forest was thinned by 50% in December 2022. Seedlings of 20 to 30 tree species were found in both stands. In addition, we collected samples of soil, branches, leaves, etc., and
measured radioactive cesium. The results showed that in the former forest stand, it was approximately 20,000 Bq/h in a 5 cm deep soil layer, and in the latter, in a 5 cm deep soil layer. Approximately 100,000 Bq/h of radioactive cesium was detected.
Keywords: abandoned forest, tree thinning, relative illumination, sample collection, radioactive cesium -
More lianas on larger host trees on steep slopes in a secondary temperate forest, Japan Reviewed International journal
Ikumi Nakada, Iwao Uehara, Hideki Mori
Plant Ecology 225 519 - 533 2024.03
Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Springer
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New reforestation by planting and natural regeneration and welfare utilization in Japan Reviewed International journal
Iwao UEHARA
森林保健研究 4 11 - 19 2023.06
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：日本森林保健学会
Abstract:
Approximately 70% of Japan's land area is covered with forests, so it is sometimes called a forest country. There are four types of forest belts: subarctic forest, temperate forest, temperate forest, and subtropical forest, and biodiversity in the forest is high. On the other hand, however, there is an annual increasing number of "abandoned forests" where appropriate treatment such as thinning has not been done in artificial forests mainly made of cedar and cypress in Japan. Although the main reasons for this increase in abandoned forests are social factors such as the aging and declining number of forestry workers and falling log prices. To improve these conditions, it requires efficient forest management and reforestation. Traditional Japanese forestry involves planting saplings in mountains, cutting undergrowth, pruning, clearing and thinning. However, as the forestry labor force is declining, it is necessary to review the traditional way of doing things. Therefore, in this study, I introduce an example of a mixed reforestation method that combines artificial planting and natural spraying. This method can also be expected to secure biodiversity. Japanese foresters have tried to plant and make mixed forest artificially, but it is quite difficult, because Japanese forest ecosystem is so complicated and difficult to make mixed and multi-layered forest artificially. Then utilizing natural regeneration power is quite making sense on this point. Various and diverse vegetation must bring various and diverse possibilities, too, such as medical, relax, food utilization, forest therapy, even preventing COVID-19. Totally, biomass of the mixed forest must be utilized efficiently.
Keywords; abandoned forest, natural regeneration, silviculture, forest therapy, COVID-19 -
Species occurrence, regeneration and relevance of herbaceous plants on selected street lanes and public parks of Setagaya ward Reviewed International coauthorship International journal
Kibalama Marvin Bogere, Iwao UEHARA
Journal of Forest and Human Health Promotion Research 4 1 - 10 2023.06
Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：The Society of Forest
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Possibility of abandoned forest regeneration by thinning and monitoring and radioactive cesium for 10 years in Fukushima forest Reviewed
Iwao UEHARA
Journal of Forest and Human Health Promotion Research 3 11 - 28 2022.07
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：日本森林保健学会
It has been reported that some forests in the Soma area of Fukushima Prefecture have high concentrations of radioactive cesium since the accident at the Fukushima Daiichi nuclear power plant in March 2011. However, the actual situation has not been clarified in many cases, and there are still high requests for scrutiny from local residents and neighbors. Since 2011, Tokyo Agriculture University has set up multiple fixed-point observation sites in the forests of the Soma region and has been continuously measuring radiation doses. In this paper, I report the results of continuous measurement for the 10 years. In 2019, thinning in the Cryptomeria japonica plantation in Soma City and in 2020 in the Chamaecyparis obtusa plantation in Minamisoma City will be carried out in private forests of about 30 years old, and those forests before and after thinning will be carried out. As of March 2022, the number of tree species in which cesium-134 (half-life is about 2 years) or 137 (half-life is about 30 years) is not detected in the collected branch and leaf samples is gradually increasing, especially in the seedlings of broad-leaved trees and conifers by natural dispersal. The number of individuals in which both are not detected is gradually increasing. In the beginning of 2011, there were tens of thousands to hundreds of thousands of becquerels or more of forest soil, but in December 2021, there were many places where the number decreased to about 1/10. In addition, a comparison of soil depths of 5 cm and 10 cm showed that the radioactive concentration at a depth of 10 cm decreased to about 1/10 to 1/40 or less compared to a depth of 5 cm. It can be seen that radioactive falling substances are accumulated on the surface of the soil. In the thinning of the Cryptomeria japonica stand in 2019 and Chamaecyparis obtusa stand in 2020, illuminance of both of the forest floor was improved, and in the following year, new seedlings were found on each forest floor. Based on these facts, we would like to propose the creation of a mixed forest of artificially planted coniferous forests and broad-leaved trees by natural dispersal. Radioactive substances from streams in the forest have not been detected since 2011.
Keywords: forest soil, litter, thinning, abandoned artificial forest, regenerationOther Link： https://forest-and-human-health.jp/
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Distribution and characteristic tree shapes of Larix kaempferi seedlings in Okutama Practice Forest of Tokyo University of Agriculture Reviewed
Iwao UEHARA
Kanto Journal of Forest Research 73 37 - 40 2022.03
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：関東森林学会
Abstract:
Larix kaempferi is a woody plant of the genus Larix Pinaceae. It is only one native deciduous coniferous trees in Japan. Larix kaempferi is a strong intolerant tree and grows fast. It is also a pioneer species and invades bare areas such as ground covered by volcanic ash and gravel. The soil demand of Larix kaempferi is low, therefore, a colony of them is sometimes formed at sites with poor soil. However, it is rare to see the seedlings in the Okutama Practice Forest of Tokyo University of Agriculture (TUA). The distribution and characteristic tree shapes have yet to be clearly identified. Thus, this study focused on the seedlings of Larix kaempferi at 900 m above sea level around a forest road and surveyed the seedlings’ distribution and characteristic tree shape. Results showed that 1 to 5-year-old seedlings of Larix kaempferi were distributed at bright sites (relative illuminance was 70 %) in the radius of 10 m from the Larix kaempferi stand. Seedlings were distributed on the soft ground (soil hardness: 0.5 kg / cm2) among the gravel soil. The tree shape was mainly dwarf or creeping types, the leaves are 3 to 4 cm long, and T/R ratio was 1.5 on average.
Key-word: seedlings, soil hardness, Yamanaka soil hardness meter, tree shape, T/R ratio -
Understanding urban trees of Setagaya city in correlation with the interests and perceptions of forestry students Reviewed
Kibalama Marvin Bogere, Iwao Uehara
Kanto Journal of Forest Research 73 57 - 60 2022.03
Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal)
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Study on the Antibacterial Effects on Woody Plant Fragrances Invited Reviewed
292 7 - 21 2021.12
Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal)
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Case study of campus practice as an alternative forest practice responding COVID-19 Reviewed
72 ( 1 ) 41 - 44 2021.03
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)
COVID-19 has been spread out world widely since it had been reported in Wuhan city in China in 2019. It has brought various limitations in our daily lives and it has given negative impacts on schools and campus lives, too. Therefore, educational society has mainly taken measures website delivery learning materials against COVID-19. In these sequences, forest departments of Japanese universities have also planned alternative practices of field practices. This study showed a case of campus practice as an alternative forest practice and considered the effects at Tokyo University of Agriculture. Totally 130 students were belong to 6 groups (approximately 20 students each) and each groups were divided to 5 training teams (4 students each) to keep physical distance. Contents of the practice were every tree survey (tree height, diameter at breast height: DBH), canopy projection drawing, soil cross section drawing, soil hand sorting, and tree identification on campus. These alternative practice showed some problems that were lack of dynamic forest practices such as thinning, making soil cross section, differences between forest tree species (Cryptomeria japonica and Chamaecyparis obtusa) and green planting species(Zelkova serrata and Ginkgo biloba), stand density, and so forth.
Key word: COVID-19, campus practice, alternative forest practice, silviculture, sophomore studentsOther Link： http://www.kantoforest.jp/
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Ectomycorrhizal fungal communities in the boundary between secondary broad-leaved forests and Japanese cypress plantations Reviewed
Akira Ishikawa, Iwao Uehara, Megumi Tanaka
Journal of Forest Research 25 ( 6 ) 397 - 404 2020.11
Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal)
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Student training at Okutama Practice Forest of Tokyo University of Agriculture Reviewed
68 17 - 20 2020.04
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：The Chubu Forestry Society
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Distribution and crown shape changing of Lindera praecox under the artificial Cryptomeria japonica and Chamacyparis obtusa canopies Reviewed
Iwao UEHARA
関東森林研究 71 ( 1 ) 53 - 56 2020.03
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：関東森林学会
Abstract:
Lindera praecox is a woody plant of Camphoraceae, Lindera that has peculiar fragrance. It contains oily component and it has been used for firewood. Its fruit had made desk lamp oil, too. Natural distribution of Lindera praecox broads Honshu Island to Kyushu Island in Japan. It can grow on the floor and edge of artificial Criptmeria japonica and Chamaecyparis obtusa stands. However, the characteristic features of Lindera praecox under the canopies of Cryptomeria and Chamaecyparis stands has not been clear yet. Then, this study surveyed the condition of distribution, density, and tree shape variation of Lindera praecox under the canopies condition. The survey site was 50-year artificial Cryptomeria and Chamaecyparis stands located in 500 altitude in Kosuge village, Yamanashi Prefecture. The stand incline was approximately 25 degree. Lindera praecox formed second canopies under the canopies. Their crowns transformed their shape into two types that were vertical and horizontal direction. Their branches and leaves might develop stepped shape for light reception and corresponding the incline. These results suggested that the tree shape might be used as an indicator of the stand condition. It should keep Lindera praecox without cutting under the Cryptomeria and Chamaecyparis canopies at steep stands to prevent soil erosion.
Key word: under the canopies of Cryptomeria japonica and Chamaecyparis obtusa, Lindera praecox, distribution, characteristic features -
Distribution of natural regenerated Lindera umbellata at artificial Chamaecyparis obtusa floor by several thinning rates Reviewed
Iwao UEHARA
関東森林研究 70 ( 2 ) 157 - 160 2020.02
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：関東森林学会
Thinning cut facilitates natural regeneration of woody species on the forest floor.
This research surveyed the natural regeneration of Lindera umbellata at the floor of artificial Chamaecyparis obtusa stand. It also aimed to reconsider how thinning rate have effects on the distribution of Lindera umbellata. The survey plots were 30%, 50%, 70% thinning, and control plot in a 50-year Chamaecyparis obtusa stand and each plot area was 400㎡. The average tree height of Chamaecyparis obtusa was 17.5m, the average DBH was 24cm, and the average crown height was over 6.5m.
The results showed the appearance rate of Lindera umbellata seedlings was 1 to 3% of all seedlings except Chamaecyparis obtusa. Thinning rate and relative illumination and the tree height had correlation.
These results suggested it has some possibility of forest floor cultivation of Lindera umbellata. There was no correlation between thinning rate and relative illumination and chlorophyll amount of the leaves of Lindera umbellata.
Key-words: natural regeneration, floor vegetation, appearance rate, space dominant, SPAD -
Intake of Radionuclides in the tree of Fukushima Forests 2. Study of radiocesium flow to poplar seedlings as a model tree Reviewed
Nonaka Miki , Yasukawa Chisato , Itakura Masateru , Tsubokura Masaharu , Baba Kei'ichi , Ohbayashi Hiroya , Seyama Tomoko , Uehara Iwao , Kaida Rumi , Taji Teruaki , Sakata Yoichi , Hayashi Takahisa
Forests 10 ( 9 ) 736 - 744 2019.09
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)