The effects of elevated CO2, elevated O3, elevated temperature, and drought on plant leaf gas exchanges: a global meta-analysis of experimental studies.

Jinmeng Zhang, Lei Deng, Hong Jiang, Changhui Peng, Chunbo Huang, Minxia Zhang, Xiuying Zhang

Environmental science and pollution research international 2021 Mar

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Global change significantly influences plant leaf gas exchange, which affects the carbon-water cycle of terrestrial ecosystems. However, the magnitudes of the effects of multiple global change factors on leaf gas exchanges are currently lacking. Therefore, a global meta-analysis of 337 published articles was conducted to determine the effects of elevated CO2 (eCO2), elevated O3 (eO3), elevated temperature (eT), and drought on plant leaf gas exchanges. The results indicated that (1) the overall responses of photosynthesis rate (Pn) and instantaneous water use efficiency (WUEi) to eCO2 increased by 28.6% and 58.6%. But transpiration rate (Tr) and stomatal conductance (gs) responded negatively to eCO2 (- 17.5% and - 17.2%, respectively). Furthermore, all Pn, gs, and WUEi responded negatively to eO3 (- 32.7%, - 24.6%, and - 27.1%), eT (- 23.2%, - 10.8%, and - 28.9%), and drought (- 53.6%, - 59.3%, and - 4.6%, respectively), regardless of functional groups and various complex experimental conditions. (2) Elevated CO2 increased WUEi combined with eO3, eT, and drought (26.6%, 36.0%, and 58.6%, respectively, for eCO2 + eO3, eCO2 + eT, and eCO2 + drought) and mitigated their negative impacts on Pn to some extent. (3) Plant form and foliage type play an important role in the responses of leaf gas exchanges. Trees responded mostly to eCO2, but responded least to eT in Pn, Tr, gs, and WUEi compared with shrubs and herbs. Evergreen broad-leaved species were more responsive to eCO2 and drought. (4) The stress level of each factor can also significantly influence the responses of leaf gas exchanges to environment change. Hopefully, the quantitative results are helpful for the further assessments of the terrestrial carbon-water cycle.

Citation

Jinmeng Zhang, Lei Deng, Hong Jiang, Changhui Peng, Chunbo Huang, Minxia Zhang, Xiuying Zhang. The effects of elevated CO2, elevated O3, elevated temperature, and drought on plant leaf gas exchanges: a global meta-analysis of experimental studies. Environmental science and pollution research international. 2021 Mar;28(12):15274-15289