Yan, H, Wang, S-Q, Da Rocha, HR et al. (5 more authors) (2017) Simulation of the Unexpected Photosynthetic Seasonality in Amazonian Evergreen Forests by Using an Improved Diffuse Fraction‐Based Light Use Efficiency Model. Journal of Geophysical Research: Biogeosciences, 122 (11). pp. 3014-3030. ISSN 2169-8953
Abstract
Understanding the mechanism of photosynthetic seasonality in Amazonian evergreen forests is critical for its formulation in global climate and carbon cycle models. However, the control of the unexpected photosynthetic seasonality is highly uncertain. Here we use eddy‐covariance data across a network of Amazonian research sites and a novel evapotranspiration (E) and two‐leaf‐photosynthesis‐coupled model to investigate links between photosynthetic seasonality and climate factors on monthly scales. It reproduces the GPP seasonality (R2 = 0.45–0.69) with a root‐mean‐square error (RMSE) of 0.67–1.25 g C m⁻² d⁻¹ and a Bias of −0.03–1.04 g C m⁻² d⁻¹ for four evergreen forest sites. We find that the proportion of diffuse and direct sunlight governs the photosynthetic seasonality via their interaction with sunlit and shaded leaves, supported by a proof that canopy light use efficiency (LUE) has a strong linear relationship with the fraction of diffuse sunlight for Amazonian evergreen forests. In the transition from dry season to rainy season, incident total radiation (Q) decreased while LUE and diffuse fraction increased, which produced the large seasonal increase (~34%) in GPP of evergreen forests. We conclude that diffuse radiation is an important environmental driver of the photosynthetic seasonality in tropical Amazon forests yet depending on light utilization by sunlit and shaded leaves. Besides, the GPP model simulates the precipitation‐dominated GPP seasonality (R² = 0.40–0.69) at pasture and savanna sites. These findings present an improved physiological method to relate light components with GPP in tropical Amazon.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2017 American Geophysical Union. Reproduced in accordance with the publisher's self-archiving policy. |
Keywords: | photosynthetic seasonality; light use efficiency; diffuse fraction; gross primary production; evapotranspiration; Amazonian forest |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst for Climate & Atmos Science (ICAS) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 29 Nov 2017 11:00 |
Last Modified: | 14 Jun 2018 00:39 |
Status: | Published |
Publisher: | American Geophysical Union |
Identification Number: | 10.1002/2017JG004008 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:124617 |