Effects of Combined CO2 and O3 Exposures on Net CO2 Assimilation and Biomass Allocation in Seedlings of the Late-Successional Fagus Crenata
by
Hiroyuki Tobita 1,*, Masabumi Komatsu 1, Hisanori Harayama 2
, Kenichi Yazaki 1, Satoshi Kitaoka 1 and Mitsutoshi Kitao 2
Hiroyuki Tobita 1,*, Masabumi Komatsu 1, Hisanori Harayama 2, Kenichi Yazaki 1, Satoshi Kitaoka 1 and Mitsutoshi Kitao 2
1
Department of Plant Ecology, Forestry and Forest Products Research Institute, Matsunosato 1, Tsukuba 305-8687, Japan
2
Hokkaido Research Center, Forestry and Forest Products Research Institute, Hitsujigaoka 7, Sapporo 062-8516, Japan
*
Author to whom correspondence should be addressed.
Climate 2019, 7(10), 117; https://doi.org/10.3390/cli7100117
Received: 15 July 2019 / Revised: 21 September 2019 / Accepted: 21 September 2019 / Published: 26 September 2019
(This article belongs to the Special Issue Air Pollution and Plant Ecosystems)
We examined the effects of elevated CO2 and elevated O3 concentrations on net CO2 assimilation and growth of Fagus crenata in a screen-aided free-air concentration-enrichment (FACE) system. Seedlings were exposed to ambient air (control), elevated CO2 (550 µmol mol−1 CO2, +CO2), elevated O3 (double the control, +O3), and the combination of elevated CO2 and O3 (+CO2+O3) for two growing seasons. The responses in light-saturated net CO2 assimilation rates per leaf area (Agrowth-CO2) at each ambient CO2 concentration to the elevated CO2 and/or O3 treatments varied widely with leaf age. In older leaves, Agrowth-CO2 was lower in the presence of +O3 than in untreated controls, but +CO2+O3 treatment had no effect on Agrowth-CO2 compared with the +CO2 treatment. Total plant biomass increased under conditions of elevated CO2 and was largest in the +CO2+O3 treatment. Biomass allocation to roots decreased with elevated CO2 and with elevated O3. Elongation of second-flush shoots also increased in the presence of elevated CO2 and was largest in the +CO2+O3 treatment. Collectively, these results suggest that conditions of elevated CO2 and O3 contribute to enhanced plant growth; reflecting changes in biomass allocation and mitigation of the negative impacts of O3 on net CO2 assimilation.
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MDPI and ACS Style
Tobita, H.; Komatsu, M.; Harayama, H.; Yazaki, K.; Kitaoka, S.; Kitao, M. Effects of Combined CO2 and O3 Exposures on Net CO2 Assimilation and Biomass Allocation in Seedlings of the Late-Successional Fagus Crenata. Climate 2019, 7, 117.
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