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https://doi.org/10.1111/gcb.16503
Title: | Vegetation clumping modulates global photosynthesis through adjusting canopy light environment | Authors: | Li, Fa Hao, Dalei Zhu, Qing Yuan, Kunxiaojia Braghiere, Renato K He, Liming Luo, Xiangzhong Wei, Shanshan Riley, William J Zeng, Yelu Chen, Min |
Keywords: | Science & Technology Life Sciences & Biomedicine Biodiversity Conservation Ecology Environmental Sciences Biodiversity & Conservation Environmental Sciences & Ecology canopy structure clumping index gross primary production radiative transfer terrestrial biosphere modeling LEAF-AREA INDEX RADIATIVE-TRANSFER DIFFUSE-RADIATION CARBON-DIOXIDE ENERGY FLUXES BIG-LEAF MODIS MODEL CO2 FOREST |
Issue Date: | 8-Nov-2022 | Publisher: | WILEY | Citation: | Li, Fa, Hao, Dalei, Zhu, Qing, Yuan, Kunxiaojia, Braghiere, Renato K, He, Liming, Luo, Xiangzhong, Wei, Shanshan, Riley, William J, Zeng, Yelu, Chen, Min (2022-11-08). Vegetation clumping modulates global photosynthesis through adjusting canopy light environment. GLOBAL CHANGE BIOLOGY 29 (3). ScholarBank@NUS Repository. https://doi.org/10.1111/gcb.16503 | Abstract: | The spatial dispersion of photoelements within a vegetation canopy, quantified by the clumping index (CI), directly regulates the within-canopy light environment and photosynthesis rate, but is not commonly implemented in terrestrial biosphere models to estimate the ecosystem carbon cycle. A few global CI products have been developed recently with remote sensing measurements, making it possible to examine the global impacts of CI. This study deployed CI in the radiative transfer scheme of the Community Land Model version 5 (CLM5) and used the revised CLM5 to quantitatively evaluate the extent to which CI can affect canopy absorbed radiation and gross primary production (GPP), and for the first time, considering the uncertainty and seasonal variation of CI with multiple remote sensing products. Compared to the results without considering the CI impact, the revised CLM5 estimated that sunlit canopy absorbed up to 9%–15% and 23%–34% less direct and diffuse radiation, respectively, while shaded canopy absorbed 3%–18% more diffuse radiation across different biome types. The CI impacts on canopy light conditions included changes in canopy light absorption, and sunlit–shaded leaf area fraction related to nitrogen distribution and thus the maximum rate of Rubisco carboxylase activity (Vcmax), which together decreased photosynthesis in sunlit canopy by 5.9–7.2 PgC year−1 while enhanced photosynthesis by 6.9–8.2 PgC year−1 in shaded canopy. With higher light use efficiency of shaded leaves, shaded canopy increased photosynthesis compensated and exceeded the lost photosynthesis in sunlit canopy, resulting in 1.0 ± 0.12 PgC year−1 net increase in GPP. The uncertainty of GPP due to the different input CI datasets was much larger than that caused by CI seasonal variations, and was up to 50% of the magnitude of GPP interannual variations in the tropical regions. This study highlights the necessity of considering the impacts of CI and its uncertainty in terrestrial biosphere models. | Source Title: | GLOBAL CHANGE BIOLOGY | URI: | https://scholarbank.nus.edu.sg/handle/10635/243480 | ISSN: | 1354-1013 1365-2486 |
DOI: | 10.1111/gcb.16503 |
Appears in Collections: | Elements Staff Publications |
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