Effects of Elevated CO 2 Concentrations on Leaf Senescence and Late-Season Net Photosynthesis of Red Maple ( Acer rubrum
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Effects of Elevated CO2 Concentrations on Leaf Senescence and Late-Season Net Photosynthesis of Red Maple (Acer rubrum) Li Li & William Manning & Xiaoke Wang
Received: 20 May 2020 / Accepted: 20 August 2020 # Springer Nature Switzerland AG 2020
Abstract To investigate the effects of elevated atmospheric CO2 concentrations ([CO2]) on autumnal phenology and end of season photosynthesis of different bud-break leaves of trees, we fumigated 2-year-old red maple seedlings with 800, 600, and 400 μL L−1 [CO2] in nine continuous stirred tank reactor (CSTR) chambers. Leaves were subdivided into first (B1), second (B2), and third bud-break (B3) leaves. The results indicated that (1) autumnal leaf senescence, including the beginning date, end date, and duration of leaf abscission of all three bud-break leaf groups, was not affected by elevated [CO2]; (2) elevated [CO2] increased leaf photosynthesis of B1, B2, and B3 leaves throughout the whole of the growing season; (3) elevated [CO2] significantly increased whole plant photosynthesis only for B2 leaves, accounting for 41.2–54.7% of the whole plant photosynthesis, due to the larger whole leaf area of B2. In conclusion, enhanced seasonal carbon gain in response to atmospheric CO2 enrichment is the result of strong
L. Li Co-Innovation Centre for Sustainable Forestry in Southern China, College of Biology and the Environment, Bamboo Research Institute, Nanjing Forestry University, Nanjing 210037, China L. Li (*) : X. Wang State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China e-mail: [email protected] W. Manning Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, USA
stimulation of photosynthesis throughout the growing season, especially for B2 leaves but not by extending or shortening the growing season in autumn. Keywords Elevated CO2 . Leaf demography . Lateseason net photosynthesis . Autumnal leaf phenology
1 Introduction Elevated atmospheric [CO2] has been shown to affect the growth rhythm of forest trees by altering the timing of spring bud-break (Bigras and Bertrand 2006), flowering (Springer and Ward 2007), and autumnal leaf senescence (Taylor et al. 2008; Tallis et al. 2010; Warren et al. 2011). The timing of autumnal leaf senescence has a significant impact on plant carbon gain, which is directly affected by how many leaves are maintained on the plant and their photosynthetic rates, especially during the late season. However, results from previous experiments, performed with a variety of methods ranging from controlled indoor growth chambers to open-top chambers to free-air CO2 enrichment (FACE) experiments in the field, showed a large variability of specific forest trees going into the autumnal phenophase in response to elevated [CO2]. The response ranged from advances (Warren et al. 2011; Quercus in Asshoff et al. 2006; Sigurdsson 2001; McConnaughay et al. 1996) to delays (Taylor et al. 2008; Tallis et al. 2010; Carpinus and Fagus in Ass
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