Preprints
https://doi.org/10.5194/egusphere-2025-4102
https://doi.org/10.5194/egusphere-2025-4102
30 Sep 2025
 | 30 Sep 2025
Status: this preprint is open for discussion and under review for Biogeosciences (BG).

Multi-scale dynamics of carbon dioxide flux and its environmental drivers in the Pantanal wetland

Tarcis A. O. dos Santos, Alberto S. de Arruda, Paulo H. Z. de Arruda, and Gilney F. Zebende

Abstract. Understanding carbon flux dynamics in tropical ecosystems is crucial for evaluating their role in global climate regulation. This study investigates the temporal variability of the net ecosystem exchange (NEE) of CO2 and its interactions with key meteorological variables in a tropical forest ecosystem of the Pantanal, Brazil. Using high-resolution hourly data from a flux tower, we apply Detrended Fluctuation Analysis (DFA) and Detrended Cross-Correlation Analysis (DCCA) to analyze diurnal to seasonal cycles of NEE, latent heat (LE), sensible heat (H), global radiation (Rg), air and soil temperature (Tair and Tsoil), relative humidity (rH), and vapor pressure deficit (VPD). The results reveal a strong diurnal coupling between solar radiation, temperature, and carbon fluxes, with peak CO2 uptake occurring at midday. A key novel finding is a marked shift to strong anti-persistence in NEE at the weekly scale during the dry season, a pattern supported by concurrent reductions in LE and rH and increases in H and VPD. This highlights that water limitation is a critical driver of carbon release and reveals a previously unidentified regulatory mechanism in the ecosystem's carbon cycle. These findings underscore the sensitivity of carbon dynamics to hydrometeorological conditions and underline the necessity of multi-scale analysis. Uncertainties remain regarding the role of extreme droughts and floods, as well as land-use dynamics, which merit further investigation.

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Tarcis A. O. dos Santos, Alberto S. de Arruda, Paulo H. Z. de Arruda, and Gilney F. Zebende

Status: open (until 11 Nov 2025)

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Tarcis A. O. dos Santos, Alberto S. de Arruda, Paulo H. Z. de Arruda, and Gilney F. Zebende

Data sets

Climate dataset of Brazilian pantanal wetland Paulo H. Z. de Arruda https://doi.org/10.5281/zenodo.17230250

Tarcis A. O. dos Santos, Alberto S. de Arruda, Paulo H. Z. de Arruda, and Gilney F. Zebende

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Short summary
Our study uncovers the Pantanal's fragile carbon rhythm. Using an environmental monitoring tower, we found the world's largest wetland absorbs carbon in the wet season but releases it during drought. This finely balanced, water-driven cycle is critical for predicting its response to climate change and for protecting this globally important ecosystem.
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