Kouki Hikosaka1, Niels P R Anten2, Almaz Borjigidai3, Chiho Kamiyama4, Hidemitsu Sakai5, Toshihiro Hasegawa5, Shimpei Oikawa6, Atsuhiro Iio7, Makoto Watanabe8, Takayoshi Koike9, Kazuya Nishina10, Akihiko Ito11. 1. Graduate School of Life Sciences, Tohoku University, Aoba, Sendai 980-8578, Japan, CREST, JST, Tokyo, Japan, hikosaka@m.tohoku.ac.jp. 2. Center for Crop System Analysis, Wageningen University, PO Box 430, 6700 AK Wageningen, the Netherlands. 3. Institute of Chinese Minority Traditional Medicine, Minzu University of China, Beijing, 100081, China. 4. Institute for the Advanced Study of Sustainability, United Nations University, Jingumae 5-53-70, Shibuya, Tokyo 150-8925, Japan. 5. Agro-Meteorology Division, National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604, Japan. 6. Department of Biology, Ibaraki University, Mito 310-8512, Japan. 7. Center for Education and Research in Field Science, Agricultural Faculty, Shizuoka University, Ohya, Shizuoka 422-8529, Japan. 8. Institute of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan. 9. Silviculture and Forest Ecological Studies, Hokkaido University, Sapporo 060-8589, Japan. 10. National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba 305-8506, Japan. 11. National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba 305-8506, Japan Japan Agency for Marine-Earth Science and Technology, Yokohama 236-0001, Japan.
Abstract
BACKGROUND AND AIMS: Leaf nitrogen distribution in the plant canopy is an important determinant for canopy photosynthesis. Although the gradient of leaf nitrogen is formed along light gradients in the canopy, its quantitative variations among species and environmental responses remain unknown. Here, we conducted a global meta-analysis of leaf nitrogen distribution in plant canopies. METHODS: We collected data on the nitrogen distribution and environmental variables from 393 plant canopies (100, 241 and 52 canopies for wheat, other herbaceous and woody species, respectively). KEY RESULTS: The trends were clearly different between wheat and other species; the photosynthetic nitrogen distribution coefficient (Kb) was mainly determined by leaf area index (LAI) in wheat, whereas it was correlated with the light extinction coefficient (KL) and LAI in other species. Some other variables were also found to influence Kb We present the best equations for Kb as a function of environmental variables and canopy characteristics. As a more simple function, Kb = 0·5KL can be used for canopies of species other than wheat. Sensitivity analyses using a terrestrial carbon flux model showed that gross primary production tended to be more sensitive to the Kb value especially when nitrogen content of the uppermost leaf was fixed. CONCLUSION: Our results reveal that nitrogen distribution is mainly driven by the vertical light gradient but other factors such as LAI also have significant effects. Our equations contribute to an improvement in the projection of plant productivity and cycling of carbon and nitrogen in terrestrial ecosystems.
BACKGROUND AND AIMS: Leaf nitrogen distribution in the plant canopy is an important determinant for canopy photosynthesis. Although the gradient of leaf nitrogen is formed along light gradients in the canopy, its quantitative variations among species and environmental responses remain unknown. Here, we conducted a global meta-analysis of leaf nitrogen distribution in plant canopies. METHODS: We collected data on the nitrogen distribution and environmental variables from 393 plant canopies (100, 241 and 52 canopies for wheat, other herbaceous and woody species, respectively). KEY RESULTS: The trends were clearly different between wheat and other species; the photosynthetic nitrogen distribution coefficient (Kb) was mainly determined by leaf area index (LAI) in wheat, whereas it was correlated with the light extinction coefficient (KL) and LAI in other species. Some other variables were also found to influence Kb We present the best equations for Kb as a function of environmental variables and canopy characteristics. As a more simple function, Kb = 0·5KL can be used for canopies of species other than wheat. Sensitivity analyses using a terrestrial carbon flux model showed that gross primary production tended to be more sensitive to the Kb value especially when nitrogen content of the uppermost leaf was fixed. CONCLUSION: Our results reveal that nitrogen distribution is mainly driven by the vertical light gradient but other factors such as LAI also have significant effects. Our equations contribute to an improvement in the projection of plant productivity and cycling of carbon and nitrogen in terrestrial ecosystems.