22 Sep 2023
 | 22 Sep 2023
Status: a revised version of this preprint is currently under review for the journal BG.

Elevated atmospheric CO2 and vegetation structural changes contributed to GPP increase more than climate and forest cover changes in subtropical forests of China

Tao Chen, Félicien Meunier, Marc Peaucelle, Guoping Tang, Ye Yuan, and Hans Verbeeck

Abstract. Abstract: The subtropical forest gross primary productivity (GPP) plays a pivotal role in the global carbon cycle and in regulating the global climate. Quantifying the individual and combined effects of forest cover change (FCC), vegetation structural change (VSC, i.e., leaf area index (LAI)), CO2 fertilization, and climate change (CC) on annual GPP dynamics of various subtropical forest types are essential for mitigating carbon emissions and predicting climate changes, but these impacts remain unclear. In this study, we used a processed-based model to comprehensively investigate the impacts of these factors on GPP variations with a series of model experiments in China’s subtropical forests during 2001–2018. Simulated actual GPP showed a significant increasing trend (26.72 TgC year−1, p < 0.001) under the interaction effects of these factors. The CO2 fertilization (8.23 TgC year−1, p < 0.001) and VSC (4.55 TgC year−1, p = 0.005) were the two dominant drivers of total subtropical forest GPP increase, followed by the effect of FCC (1.35 TgC year−1, p < 0.001) and CC (1.11 TgC year−1, p = 0.08). We observed different responses to drivers depending on forest types. The evergreen broadleaved forests have a high carbon sink potential due to the positive effects of all drivers. Both the FCC (1.29 TgC year−1, p < 0.001) and CC (0.53 TgC year−1, p < 0.05) significantly decreased evergreen needleleaved forest GPP, while their negative effects were almost offset by the positive impact of VSC. Our results indicated that forest structural change outweighed the forest cover change in promoting GPP, which is an overlooked driver that needs to be accounted for in studies, as well as ecological and management programs. Overall, our study offers a novel perspective on different drivers of subtropical forest GPP changes, which provides valuable information for policy makers in forest management to mitigate climate change.

Tao Chen et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on bg-2023-140', Anonymous Referee #1, 29 Oct 2023
    • AC2: 'Reply on RC1', Tao Chen, 25 Nov 2023
  • RC2: 'Comment on bg-2023-140', Anonymous Referee #2, 30 Oct 2023
    • AC1: 'Reply on RC2', Tao Chen, 25 Nov 2023

Tao Chen et al.


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Short summary
The Chinese subtropical forest ecosystems are an extremely important component of those global forest ecosystems and are hence crucial for the global carbon cycle and regional climate change. However, there is still a great uncertainty in the relationship between subtropical forest carbon sequestration and its drivers. Here, we provided the first quantitative estimates of the individual and interactive effects of different drivers on the GPP of various subtropical forest types in China.