Causality Guided Machine Learning Model on Wetland Ch4 Emissions Across Global Wetlands

Yuan, Kunxiaojia; Zhu, Qing; Li, Fa; Riley, William J.; Torn, M. S.; Chu, Housen; McNicol, Gavin; Chen, Min; Knox, Sara; Delwiche, Kyle; Wu, Huayi; Baldocchi, Dennis; Ma, Hongxu; Desai, Ankur R.; Chen, Jiquan; Sachs, Torsten; Ueyama, Masahito; Sonnentag, Oliver; Helbig, Manuel; Tuittila, Eeva‐Stiina; Jurasinski, Gerald; Koebsch, Franziska; Campbell, Dave; Schmid, Hans Peter; Lohila, Annalea; Goeckede, Mathias; Nilsson, Mats; Friborg, Thomas; Jansen, Joachim; Zona, Donatella; Euskirchen, Eugénie; Krauss, Ken W.; Bohrer, Gil; Jin, Zhenong; Liu, Licheng; Iwata, Hiroyasu; Goodrich, Jordan P.; Jackson, Robert B.

doi:10.2139/ssrn.4034619

Cited by 1 publication

(2 citation statements)

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“…For example, including CI into the model increased solar energy reaching the ground (Baldocchi & Wilson, 2001; Braghiere et al, 2019; Braghiere, Quaife, et al, 2020; Law et al, 2001) and thus enhanced the latent heat flux for evaporation broadly (Figure S7a). The transpiration latent heat flux was enhanced mainly in tropical forests (Figure S7b), suggesting higher stomata conductance and photosynthesis in the tropical forests (Chen & Zhuang, 2014; Yuan, Zhu, Riley, et al, 2022). Due to increased evaporation and transpiration, we observed a total global net water loss through evapotranspiration with the most significant loss occurred in the tropical regions (Figure S7c).…”

Section: Discussionmentioning

confidence: 99%

“…The water‐stress factor β that linearly scales GPP (a smaller β would result in a smaller GPP) (Braghiere, Gérard, et al, 2020; Verhoef & Egea, 2014) in the model generally decreased at a very small magnitude due to the use of CI (Figure S8). Therefore, CI increased stomatal conductance and GPP but also increased water loss which may limit photosynthesis especially under water‐limited conditions (Yuan, Zhu, Riley, et al, 2022). The long‐term impacts of CI on GPP need further exploration especially considering water‐limited conditions.…”

Section: Discussionmentioning

confidence: 99%

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Vegetation clumping modulates global photosynthesis through adjusting canopy light environment

Hao

Zhu

et al. 2022

Global Change Biology

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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 (V cmax ), 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

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