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OKADA Keiichi Assistant Professor |
From School 【 display / non-display 】
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Tokyo University of Agriculture Faculty of Regional Environment Science Graduated
2001.04 - 2005.03
From Graduate School 【 display / non-display 】
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Shinshu University Master Course Completed
2005.04 - 2007.03
Employment Record in Research 【 display / non-display 】
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Tokyo University of Agriculture Faculty of Bio-Industry Department of Northern Biosphere Agriculture Assistant Professor
2020.04
Research Interests 【 display / non-display 】
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mycorrhizal symbiosis
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ecosystem ecology
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matter cycling
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functional ecology
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forest ecology
Papers 【 display / non-display 】
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Exploration capacity versus specific enzymatic activity of ectomycorrhizas in response to primary productivity and soil phosphorus availability in Bornean tropical rainforests
Kei-ichi Okada, Daiki Yokoyama, Shin-ichiro Aiba, Kanehiro Kitayama
Scientific Reports 2024.02
Language：English Publishing type：Research paper (scientific journal)
<jats:title>Abstract</jats:title><jats:p>Ectomycorrhizal (ECM) fungi are functionally important in biogeochemical cycles in tropical ecosystems. Extracellular enzymatic activity of ECM on a ground-area basis is the product of two attributes; exploration capacity (ECM surface-area) and specific enzymatic activity. Here, we elucidated which attribute better explained the ECM enzymatic activity in response to different levels of soil phosphorus (P) and Nitrogen (N) availability in five Bornean tropical rainforests. We determined the surface area of ECM root tips as well as the enzymatic activities per ECM surface area for carbon (C), N and P degrading enzymes in each site. We evaluated the relationship of ECM enzyme activities with the resource availabilities of C (Above-ground net primary production; ANPP), N, and P of ECM by a generalized linear mixed model. The ECM enzymatic activities on a ground-area basis were more significantly determined by specific enzymatic activity than by the exploration capacity. Specific enzymatic activities were generally negatively affected by C (ANPP) and soil P availability. ECM fungi enhance the specific enzyme activity rather than the exploration capacity to maintain the capacity of nutrient acquisition. The less dependence of ECM fungi on the exploration capacity in these forests may be related to the limitation of C supply from host trees. We highlighted the adaptive mechanisms of ECM fungi on nutrient acquisition in tropical ecosystems through the response of enzymatic activity to nutrient availability across the elements.</jats:p>
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Long-term Consequences on Soil Fungal Community Structure: Monoculture Planting and Natural Regeneration. International journal
Minagi Naka, Shota Masumoto, Keita Nishizawa, Shunsuke Matsuoka, Shinichi Tatsumi, Yuta Kobayashi, Kureha F Suzuki, Xinyu Xu, Tomoya Kawakami, Noboru Katayama, Kobayashi Makoto, Kei-Ichi Okada, Masaki Uchida, Kentaro Takagi, Akira S Mori
Environmental management 2023.12
Language：English Publishing type：Research paper (scientific journal)
Understanding the regeneration and succession of belowground communities, particularly in forests, is vital for maintaining ecosystem health. Despite its importance, there is limited knowledge regarding how fungal communities change over time during ecosystem development, especially under different forest restoration strategies. In this study, we focused on two restoration methods used in northern Japan: monoculture planting and natural regeneration. We examined the responses of the fungal community to monoculture plantations (active tree planting) and naturally regenerated (passive regeneration) forests over a 50-year chronosequence, using natural forests as a reference. Based on DNA metabarcoding, we assessed the richness of fungal Operational Taxonomic Units (OTUs) and their dissimilarity. Our findings revealed that soil fungal richness remained stable after natural regeneration but declined in monoculture plantations, from 354 to 247 OTUs. While the compositional dissimilarity of fungal assemblages between monoculture plantations and natural forests remained consistent regardless of the time since tree planting, it significantly decreased after natural regeneration, suggesting recovery to a state close to the reference level. Notably, the composition of key functional fungal groups-saprotrophic and ectomycorrhizal- has increasingly mirrored that of natural forests over time following passive natural regeneration. In summary, our study suggests that monoculture plantations may not be effective for long-term ecosystem function and service recovery because of their limited support for soil fungal diversity. These results underscore the importance of natural regeneration in forest restoration and management strategies.
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Change of regeneration status on nurse stump associated with the stump size at cool temperate forest
Okada Kei-ichi, Nakahama Kazuki, Nishimura Yoshinori, Tokita Katsuhiro
The Japanese Forest Society Congress 134 ( 0 ) 337 2023.05
Language：English Publisher：THE JAPANESE FORESTRY SOCIETY
<p>[in Japanese]</p>
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Effects of natural regeneration and monospecies planting on organic matter decomposition
Takeuchi Rie, Nishizawa Keita, Kobayashi Yuta, Masumoto Shota, Suzuki Kureha F, Kawakami Tomoya, Kobayashi Makoto, Katayama Noboru, Okada Keiichi, Tatsumi Shinnichi, Matsuoka Shunsuke, Uchida Masaki, Takagi Kentaro, Mori Akira S
The Japanese Forest Society Congress 134 ( 0 ) 647 2023.05
Language：English Publisher：THE JAPANESE FORESTRY SOCIETY
<p>[in Japanese]</p>
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Termite sensitivity to temperature affects global wood decay rates Reviewed
Amy E. Zanne, Habacuc Flores-Moreno, Jeff R. Powell, William K. Cornwell, James W. Dalling, Amy T. Austin, Aimée T. Classen, Paul Eggleton, Kei-ichi Okada, Catherine L. Parr, E. Carol Adair, Stephen Adu-Bredu, Md Azharul Alam, Carolina Alvarez-Garzón, Deborah Apgaua, Roxana Aragón, Marcelo Ardon, Stefan K. Arndt, Louise A. Ashton, Nicholas A. Barber, Jacques Beauchêne, Matty P. Berg, Jason Beringer, Matthias M. Boer, José Antonio Bonet, Katherine Bunney, Tynan J. Burkhardt, Dulcinéia Carvalho, Dennis Castillo-Figueroa, Lucas A. Cernusak, Alexander W. Cheesman, Tainá M. Cirne-Silva, Jamie R. Cleverly, Johannes H. C. Cornelissen, Timothy J. Curran, André M. D’Angioli, Caroline Dallstream, Nico Eisenhauer, Fidele Evouna Ondo, Alex Fajardo, Romina D. Fernandez, Astrid Ferrer, Marco A. L. Fontes, Mark L. Galatowitsch, Grizelle González, Felix Gottschall, Peter R. Grace, Elena Granda, Hannah M. Griffiths, Mariana Guerra Lara, Motohiro Hasegawa, Mariet M. Hefting, Nina Hinko-Najera, Lindsay B. Hutley, Jennifer Jones, Anja Kahl, Mirko Karan, Joost A. Keuskamp, Tim Lardner, Michael Liddell, Craig Macfarlane, Cate Macinnis-Ng, Ravi F. Mariano, M. Soledad Méndez, Wayne S. Meyer, Akira S. Mori, Aloysio S. Moura, Matthew Northwood, Romà Ogaya, Rafael S. Oliveira, Alberto Orgiazzi, Juliana Pardo, Guille Peguero, Josep Penuelas, Luis I. Perez, Juan M. Posada, Cecilia M. Prada, Tomáš Přívětivý, Suzanne M. Prober, Jonathan Prunier, Gabriel W. Quansah, Víctor Resco de Dios, Ronny Richter, Mark P. Robertson, Lucas F. Rocha, Megan A. Rúa, Carolina Sarmiento, Richard P. Silberstein, Mateus C. Silva, Flávia Freire Siqueira, Matthew Glenn Stillwagon, Jacqui Stol, Melanie K. Taylor, François P. Teste, David Y. P. Tng, David Tucker, Manfred Türke, Michael D. Ulyshen, Oscar J. Valverde-Barrantes, Eduardo van den Berg, Richard S. P. van Logtestijn, G. F. (Ciska) Veen, Jason G. Vogel, Timothy J. Wardlaw, Georg Wiehl, Christian Wirth, Michaela J. Woods, Paul-Camilo Zalamea
Science 377 ( 6613 ) 1440 - 1444 2022.09
Publishing type：Research paper (scientific journal) Publisher：American Association for the Advancement of Science (AAAS)
Deadwood is a large global carbon store with its store size partially determined by biotic decay. Microbial wood decay rates are known to respond to changing temperature and precipitation. Termites are also important decomposers in the tropics but are less well studied. An understanding of their climate sensitivities is needed to estimate climate change effects on wood carbon pools. Using data from 133 sites spanning six continents, we found that termite wood discovery and consumption were highly sensitive to temperature (with decay increasing >6.8 times per 10°C increase in temperature)—even more so than microbes. Termite decay effects were greatest in tropical seasonal forests, tropical savannas, and subtropical deserts. With tropicalization (i.e., warming shifts to tropical climates), termite wood decay will likely increase as termites access more of Earth’s surface.
Books and Other Publications 【 display / non-display 】
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森林学の百科事典
日本森林学会編（ Role： Contributor）
丸善出版 2021.01
Language：Japanese Book type：Scholarly book
Misc 【 display / non-display 】
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Evaluating demographic non-equilibrium of tree population: four-decade study in a late-successional subalpine forest
Suzuki Kureha, Kitagawa Ryo, Koide Dai, Okada Kei-ichi, Mori Akira S
The Japanese Forest Society Congress 131 477 2020.05
Language：Japanese Publisher：THE JAPANESE FORESTRY SOCIETY
[in Japanese]
Scientific Research Funds Acquisition Results 【 display / non-display 】
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土壌への根系到達による倒木更新木の栄養制限緩和と更新の成否
Grant number：22K05730 2022.04 - 2025.03
日本学術振興会 科学研究費助成事業 基盤研究(C) 基盤研究(C)
岡田 慶一
Grant amount：\4160000 （ Direct Cost: \3200000 、 Indirect Cost：\960000 ）
Other External Funds 【 display / non-display 】
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根系発達と倒木腐朽度の時系列動態から紐解く倒木更新の成否
2021.06 - 2022.03
農生命科学研究所 2021 年度 若手・女性研究者支援プロジェクト
岡田慶一
Authorship：Principal investigator
Grant amount：\1000000 （ Direct Cost: \1000000 ）
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熱帯林における菌根菌の菌糸体生産と栄養獲得機能の解明
2014.04 - 2015.03
民間財団等 藤原ナチュラルヒストリー振興財団
岡田慶一
Authorship：Principal investigator Grant type：Competitive
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熱帯林における外生菌根菌の菌糸体生産と栄養獲得機能の解明
2014.04 - 2015.02
民間財団等 笹川科学研究助成
岡田慶一
Authorship：Principal investigator Grant type：Competitive
Presentations 【 display / non-display 】
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冷温帯天然林における伐根サイズに応じた針葉樹実生更新状況の変化
岡田慶一, 中濱和紀, 西村祥紀, 時田勝広
第 134 回⽇本森林学会⼤会 2023.03
Language：Japanese Presentation type：Poster presentation
Teaching Experience 【 display / non-display 】
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Exercise in Geographic Information Analysis
2022.04 Institution：Tokyo University of Agriculture
Committee Memberships 【 display / non-display 】
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Ecological Society of Japan Copy editor of Ecological Research
2015.05 - 2020.03
Committee type：Academic society