Shimpei Oikawa Plant ecologist studying leaf senescence, nitrogen use & carbon gain with special emphasis on global change issues. Contact Graduate School of Science and Engineering /College of Science Bldg. A303 Ibaraki University Mito 310-8512 Japan Email Shimpei orc Last update: May 30, 2023 Copyright Shimpei Oikawa © 2010

Researth interests Japanese The researches in our lab are driven by the following questions: 1. Why leaves of plant senesce and drop?: what are the evolutional significance and the ecophysiological mechanism controlling leaf phenology? (funded by JSPS and the Sasakawa Foundation) 2. How much nitrogen is resorbed during leaf senescence? How different are legume and non-legume species in this respect? Does the former use nitrogen more luxury? (funded by the NISSAY (Nippon Life Insurance) Foundation) and JSPS KAKENHI; and 3. How global changes influence these issues? What is their feedback to climate? 4. Which plant traits were improved and lost during crop cultivation? (funded by the Innovation Fund Project of Ibaraki University and JSPS KAKENHI) 5. Is Japanese dodder generalist or specialist? (funded by the Fujiwara Natural History Foundation) 6. What ecosystem services do invasive native species Peraria lobata (kudzu) provide? (funded by NEXCO East) 7. What is the energy cost of seed and its appendages? (funded by JSPS KAKENHI) Publications Shimpei Oikawa (2024) Changes in leaf lifespan, nitrogen resorption, and mean residence time of leaf nitrogen along a soil fertility gradient in an evergreen oak tree. Physiologia Plantarum 176(5) e14519 Miki U. Ueda, Nobuo Sakagami, Tadao Enomoto, Genki Katata, Yugo Suzuki, Yui Takase, Shimpei Oikawa (2024) Herbicide management of roadside kudzu (Pueraria lobata) vegetation doubles soil nitrification and nitrate leaching rates. Landscape and Ecological Engineering 20: 571-579 Naoki Masada, Tadao Enomoto, Genki Katata, Nobuo Sakagami, Yugo Suzuki, Shimpei Oikawa (2023) Competition between the invasive alien species Solidago altissima and the native Pueraria lobata in Japan. Botany Letters 170(4): 532-540 Genki Katata, Mirai Watanabe, Shimpei Oikawa, Akiko Takahashi, Tomohiro Kubota, Yui Takase, Tadao Enomoto, Keitaro Fukushima, Nobuo Sakagami, Miki U. Ueda, Yugo Suzuki (2023) Evidence of NOx and O3 concentration reduction by kudzu (Pueraria lobata) invasion at a Japanese highway Atmospheric Pollution Research 14(1): 101644 Ryo Tanabe, Shin-Ichi Miyazawa, Osamu Kitade, Shimpei Oikawa (2022) Effect of symbiotic N2-fixation on leaf protein contents, protein degradation and nitrogen resorption during leaf senescence in temperate deciduous woody species. Oecologia 200: 79-87 Shimpei Oikawa (2022) Supra-optimal leaf area index of a temperate liana Pueraria lobata for competition with Solidago altissima at the expense of canopy photosynthesis. Tree Physiology 42(12): 2446-2453 [The cover photo of the published issue is from this study] Ayaka Togashi, Shimpei Oikawa (2021) Leaf productivity and persistence have been improved during soybean (Glycine max) domestication and evolution. Journal of Plant Research 134: 223-233 Yui Takase, Shimpei Oikawa, Tadao Enomoto, Genki Katata, Nobuo Sakagami (2020) People's attitude towards strategies to control kudzu (Pueraria lobata (Willd.) Ohwi) during road slope revegetation. Papers on Environmental Information Science 34: 174-179 (in Japanese) Shimpei Oikawa, Yusuke Matsui, Michio Oguro, Masanori Okanishi, Ryo Tanabe, Tomoki Tanaka, Ayaka Togashi, Tomoyuki Itagaki (2020) Species-specific nitrogen resorption proficiency in legumes and nonlegumes. Journal of Plant Research 133: 639-648 [The cover photo of the published issue is from our study] Tomoki Tanaka, Chiharu Kurokawa, Shimpei Oikawa (2018) Leaf shedding increases the photosynthetic rate of the canopy in N2-fixing and non-N2-fixing woody species. Tree Physiology 38(12): 1903-1911 Shimpei Oikawa, Hitomi Ehara, Mika Koyama, Tadaki Hirose, Kouki Hikosaka, Charles P. Chen, Hirofumi Nakamura, Hidemitsu Sakai, Takeshi Tokida, Yasuhiro Usui, Toshihiro Hasegawa (2017) Nitrogen resorption in senescing leaf blades of rice exposed to Free-Air CO2 Enrichment (FACE) under different N fertilization levels. Plant and Soil 418: 231-240 Shimpei Oikawa, Koya Suno, Noriyuki Osada (2017) Inconsistent intraspecific pattern in leaf life span along nitrogen-supply gradient. American Journal of Botany 104: 342-346 Shimpei Oikawa, Elizabeth A. Ainsworth (2016) Changes in leaf area, nitrogen content and canopy photosynthesis in soybean exposed to an ozone concentration gradient. Environmental Pollution 215: 347-355 Kouki Hikosaka, Niels P.R. Anten, Almaz Borjigidai, Chiho Kamiyama, Hidemitsu Sakai, Toshihiro Hasegawa, Shimpei Oikawa, Atsuhiro Iio, Makoto Watanabe, Takayoshi Koike, Kazuya Nishina, Akihiko Ito (2016) A meta-analysis of leaf nitrogen distribution within plant canopies. Annals of Botany 118: 239-247 Takahiro Ogawa, Shimpei Oikawa, Tadaki Hirose (2016) Nitrogen-utilization efficiency in rice: an analysis at leaf, shoot, and whole-plant level. Plant and Soil 404: 321-344 Kouki Hikosaka, Takehiro Sasaki, Chiho Kamiyama, Masatoshi Katabuchi, Shimpei Oikawa, Masaya Shimazaki, Hiroshi Kimura and Tohru Nakashizuka (2015) Trait-based approaches for understanding species niche, coexistence, and functional diversity in subalpine moorlands. In: Gaku Kudo (ed), Structure and Function of Mountain Ecosystems in Japan. Springer Takahiro Ogawa, Shimpei Oikawa, Tadaki Hirose (2015) Leaf dynamics in growth and reproduction of Xanthium canadense as influenced by stand density. Annals of Botany116: 807-819 Noriyuki Osada, Shimpei Oikawa, Kaoru Kitajima (2014) Implications of lifespan variation within a leaf cohort for evaluation of the optimal timing of leaf shedding. Functional Ecology 29: 308-34 Chiho Kamiyama, Shimpei Oikawa, Kouki Hikosaka (2014) Seasonal change in light partitioning among coexisting species of different functional groups along elevation gradient in subalpine moorlands. New Phytologist 20: 913-923 Kouki Hikosaka, Takehiro Sasaki, Chiho Kamiyama, Masatoshi Katabuchi, Shimpei Oikawa, Masaya Shimazaki, Hiroshi Kimura and Tohru Nakashizuka (2014) Understanding of species niche, coexistence and extinction based on functional traits: approaches from community and physiological ecology for subalpine moorland plant communities. Chikyukankyo 19: 33-46 (In Japanese) Shimpei Oikawa, Masumi Okada, Kouki Hikosaka (2013) Effects of elevated CO2 on leaf area dynamics in nodulating and non-nodulating soybean stands. Plant and Soil 373: 627-639 Noriyuki Osada, Shimpei Oikawa, Onno Muller, Rie Miyata (2013) Future perspectives of the study of leaf lifespan. Japanese Journal of Ecology 63: 81-83 (In Japanese) Shimpei Oikawa, Noriyuki Osada (2013) Leaf shedding and whole-plant carbon gain. Japanese Journal of Ecology 63: 59-67 (In Japanese) Noriyuki Osada, Shimpei Oikawa, Rie Miyata, Chiho Kamiyama, Soichiro Nagano, Satomi Shiodera, Azusa Tabata, Kiyomi Ono (2013) Patterns of within-species variation in leaf lifespan in relation to environmental factors: General trends and differences across species of different functional types. Japanese Journal of Ecology 63: 19-36 (In Japanese) Shimpei Oikawa, Noriyuki Osada, Yoshiyuki Miyazawa, Rie Miyata, Onno Muller (2013) A brief history of leaf lifespan research. Japanese Journal of Ecology 63: 11-17 (In Japanese) Zhu Chunwu, Weigo Chen, Hidemitsu Sakai, Shimpei Oikawa, Rebecca C Laza, Yasuhiro Usui, Toshihiro Hasegawa (2013) Effects of elevated [CO2] on stem and root lodging among rice cultivars. Chinese Science Bulletin 58: 1787-1794 Tadaki Hirose, Shimpei Oikawa (2012) Mean residence time: leaf number, area, dry mass, and nitrogen in canopy photosynthesis. Oecologia 169: 927-937 Toshihiko Kinugasa, Takashi Sato, Shimpei Oikawa, Tadaki Hirose (2011) Demand and supply of N in seed production of soybean (Glycine max) at different N fertilization levels after flowering. Journal of Plant Research 125: 275-281 Kouki Hikosaka, Shimpei Oikawa, Toshihiko Kinugasa, Yusuke Onoda, Tadaki Hirose (2011) Effects of elevated CO2 concentration on seed production in C3 annual plants. Journal of Experimental Botany 62: 1523-1530 Chiho Kamiyama, Shimpei Oikawa, Takuya Kubo, Kouki Hikosaka (2010) Light interception in species with different functional groups coexisting in moorland plant communities. Oecologia 164: 591-599 Shimpei Oikawa, Kay-May Miyagi, Kouki Hikosaka, Masumi Okada, Toshinori Matsunami, Makie Kokubun, Toshihiko Kinugasa, Tadaki Hirose (2010) Interactions between elevated CO2 and N2-fixation determine soybean yield - a test using a non-nodulated mutant. Plant and Soil 330: 163-172 Shimpei Oikawa (2008) Structure of herbaceous plant stands and canopy photosynthesis models. In: Low Temperature Science Vol. 67 (Eds. Institute of Low Temperature Science, Hokkaido University and The Japanese Association for Photosynthesis Research), pp.103-112 (In Japanese) (Erratum) Yosuke Matsumoto, Shimpei Oikawa, Yuko Yasumura, Tadaki Hirose, Kouki Hikosaka (2008) Reproductive yield of individuals competing in a dense stand of an annual, Xanthium canadense. Oecologia 157: 185-195 Shimpei Oikawa, Kouki Hikosaka, Tadaki Hirose (2008) Does leaf shedding increase the whole-plant carbon gain despite some nitrogen being lost with shedding? New Phytologist 178: 617-624 Shimpei Oikawa, Kouki Hikosaka, Tadaki Hirose (2006) Leaf lifespan and lifetime carbon gain of individual leaves in a stand of an annual herb, Xanthium canadense. New Phytologist 172: 104-116 (This article appeared in Virtual Special Issue on 'Plant ecological strategy axes in leaf and wood traits' of New Phytologist in June 2008 again.) Shimpei Oikawa, Kouki Hikosaka, Tadaki Hirose (2005) Dynamics of leaf area and nitrogen in a canopy of an annual herb, Xanthium canadense. Oecologia 143: 517-526 Shimpei Oikawa, Kouki Hikosaka, Tadaki Hirose, Masae Shiyomi, Shigeo Takahashi, Yoshimichi Hori (2004) Cost-benefit relationships in fronds emerging at different times in a deciduous fern, Pteridium aquilinum. Canadian Journal of Botany 82: 521-527 Experience Associate professor, College of Science, Ibaraki University (2015-present) Assistant professor, College of Science, Ibaraki University (2013-2014) Post-doctoral research fellow, Tokyo University of Agriculture (2010-2012) Influence of CO2 and nitrogen fertilization on leaf turnover, growth and seed production of rice under Free-air CO2 enrichment. Visiting scholar, Department of Plant Biology, University of Illinois (2009) Nitrogen dynamics and dry matter production in a ozone-sensitive- and a less-sensitive soybean along O3 gradients. Post-doctoral research fellow, Center for Bioresource Field Science, Kyoto Institute of Technology/Japan Society for the Promotion of Science (2007-2008) Optimal timing of leaf shedding for carbon gain of leaf and plant. Post-doctoral research fellow, Graduate School of Life Sciences, Tohoku University (2005-2006) Interspecific competition for resources and aboveground productivity in wetland plant communities along an altitudinal gradient. Back