the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 30 Sep 2025
Multi-scale dynamics of carbon dioxide flux and its environmental drivers in the Pantanal wetland
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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Status: final response (author comments only)
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RC1: 'Comment on egusphere-2025-4102', Anonymous Referee #2, 28 Oct 2025
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CC1: 'Reply on RC1', Gilney Zebende, 29 Oct 2025
We appreciate the reviewer's comments.
We agree with your comments, and yes, we will look at Table 5 and what is written on lines 357 and 356.
In the final version, a map (illustration) of the location will be added to the paper.
Citation: https://doi.org/10.5194/egusphere-2025-4102-CC1 -
AC2: 'Reply on RC1', Tarcis Santos, 12 Nov 2025
We appreciate the referee's suggestions, and as Zebende mentioned earlier above (https://doi.org/10.5194/egusphere-2025-4102-CC1), we will revise the content of line 370 and add the figure showing the data collection location.
Citation: https://doi.org/10.5194/egusphere-2025-4102-AC2
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CC1: 'Reply on RC1', Gilney Zebende, 29 Oct 2025
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RC2: 'Comment on egusphere-2025-4102', Anonymous Referee #1, 09 Nov 2025
The article entitled “Multi-scale dynamics of carbon dioxide flux and its environmental drivers in the Pantanal wetland” evaluates the temporal variability and interdependence between Net Carbon Exchange in the Ecosystem, using two very well-chosen and widely validated tools in the literature for this type of analysis: autocorrelation, using the DFA method, and cross-correlation, using the ρDCCA coefficient.
Materials and MethodologyI verify that the methodology employed was given adequate treatment. The conditions described in the manuscript are clear and coherent, allowing other researchers to replicate the study without ambiguous interpretations. The description of the DFA methods and the ρDCCA cross-correlation coefficient is written in a clear and mathematically formal manner.
Relation of techniques in preliminary results
i) Table 1 describes the interpretation of the αDFA exponent, referring to five conditions.
The point of attention is related to the values found in the adjustments presented in Table 3.
It is observed that, for the daily verification, in Tair and Tsoil, the αDFA values were 1.51 and 1.55, respectively.
According to the literature, αDFA values close to 1.5 indicate a type of random (Brownian noise) signal, whose variations over time are highly correlated. This differs from a non-stationary signal, whose statistical properties (such as mean, variance, and autocorrelation) vary over time.
The question that arises is:
Wouldn't it be interesting to add the αDFA value for values greater than 1.5 to Table 1 and justify this in the text?ii) In Table 2, the authors present the interpretation of the ρDCCA coefficient, but describe it in the caption as the DFA exponent. I believe this should be revised.
iii) The same mistake occurs in Table 3. The table shows the calculated αDFA values, but the caption describes it as the interpretation of ρDCCA. I also suggest reviewing this.
iv) I did not identify a clear description of the persistence levels in the text; only the information that values above 0.5 indicate persistent behavior. The text mentions 0.85 as moderate persistence, but to validate this statement, the authors should explain what they consider to be weak, moderate, and strong persistence.Personally, I believe it would be sufficient to indicate only the term persistence, without the subdivision. I recommend reviewing this point.
Regarding the ρDCCA coefficient
The results presented by the model are clear and consistent; I have no further observations to make regarding this part.Overall assessment
The proposal presented here is a rigorous and intellectually refined study that significantly contributes to advancing the understanding of carbon-climate interactions in a highly specific and relevant ecosystem.
Regarding the methodology and methods employed, there is soundness and consistency.
I understand that the contributions are relevant and I RECOMMEND the manuscript for publication, with the only caveat being the points mentioned above, which should be improved.Citation: https://doi.org/10.5194/egusphere-2025-4102-RC2 -
AC1: 'Reply on RC2', Tarcis Santos, 10 Nov 2025
We appreciate the reviewer’s careful reading and constructive suggestions. Regarding point (i), we agree to expand the interpretation table for the DFA scaling exponent α to explicitly include the Brownian case (α≈1.5) and values above 1.5. In the revised manuscript, Table 1 will distinguish stationary (0<α<1) from non-stationary (α>1) regimes and single out α≈1.5 as the random-walk (integrated white-noise) limit. We will also add a short note in the Methods clarifying this distinction and explaining that, at the daily window, the values obtained for Tair (α=1.51) and Tsoil (α=1.55) are consistent with random-walk-like behavior driven by strong diurnal trends and thermal inertia at that scale.
Concerning points (ii) and (iii), we will correct the captions so they match the content of each table: During layout, the table that lists the eight environmental variables with a brief description of each was mistakenly left out of the compiled manuscript. We have re-organized and renumbered all tables, checked the cross-references, and revised the captions where needed. In the next submission, the tables will be in the correct order and the variables table will be included.
For point (iv), we will remove subjective qualifiers such as “weak,” “moderate,” and “strong” when referring to α. Instead, we will simply state anti-persistent (α<0.5), uncorrelated (α=0.5), or persistent (α>0.5), always reporting the numeric value. Categorical ranges will be retained only for ρDCCA, where they serve as a quick visual guide to correlation level.
We are grateful for the positive overall assessment and for the clear endorsement of our methodological choices. All the above corrections and clarifications will be incorporated into the revised submission.
Citation: https://doi.org/10.5194/egusphere-2025-4102-AC1 -
CC2: 'Reply on AC1', Gilney Zebende, 11 Nov 2025
Dear,
We can put in the reference list this paper: "Theoretical foundation of detrending methods for fluctuation analysis such as detrended
fluctuation analysis and detrending moving average", https://journals.aps.org/pre/pdf/10.1103/PhysRevE.99.033305Citation: https://doi.org/10.5194/egusphere-2025-4102-CC2
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CC2: 'Reply on AC1', Gilney Zebende, 11 Nov 2025
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AC1: 'Reply on RC2', Tarcis Santos, 10 Nov 2025
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AC3: 'Comment on egusphere-2025-4102', Tarcis Santos, 17 Nov 2025
Dear Reviewers,
We would like to express our sincere gratitude for the time, rigor, and depth dedicated to the evaluation of our manuscript, "Multi-scale dynamics of carbon dioxide flux and its environmental drivers in the Pantanal wetland." The detailed analyses and constructive comments from both reviewers have been invaluable, contributing significantly to the improvement and clarity of the article.
Specific Gratitude to Reviewer 1: We are immensely thankful for the comprehensive assessment, the complimentary remarks on the manuscript's structure, methodological rigor, and writing quality. We were particularly pleased that the findings on the multi-scale dynamics of carbon-climate interactions in the Pantanal, using Detrended Cross-Correlation Analysis (DCCA), were perceived as a robust and insightful contribution to ecosystem and climate modeling. Your specific suggestions were promptly addressed: the section at Line 370 was revised to eliminate redundancy, and we included a map of the study site and an image of the set-up of the measurement tower (eddy covariance) as an insert in the Materials and Methods section, which indeed enhances the study's context.
Specific Gratitude to Reviewer 2: We appreciate the recognition of the adequacy of the methodological treatment, particularly the choice and application of the DFA and DCCA methods, and the assessment of the clarity and mathematical formality in the description of the techniques. Your comments were crucial for enhancing the precision and consistency of the tables and the text. Following your recommendations: (i) we added the interpretation for $\alpha_{DFA}$ greater than 1.5 (Brownian Noise) to Table 1 and included a justification in the text for this type of highly correlated and non-stationary signal ($T_{air}$ and $T_{soil}$), enriching the discussion on persistence characteristics; (ii) we corrected the errors in the captions of Table 2 and Table 3, ensuring the terms $\rho_{DCCA}$ and $\alpha_{DFA}$ were correctly described; (iii) we removed the subdivision into 'weak', 'moderate', and 'strong' persistence from the text, focusing only on the term "persistence" (values above 0.5) to maintain parsimony and avoid ambiguity.
Both reviews confirmed the relevance of studying the Pantanal, and the revisions performed have made the manuscript more rigorous, cohesive, and clear. We thank you once again for your valuable contributions and are confident that the revised article meets the journal's high standards.
Sincerely,
The Authors
Citation: https://doi.org/10.5194/egusphere-2025-4102-AC3
Data sets
Climate dataset of Brazilian pantanal wetland Paulo H. Z. de Arruda https://doi.org/10.5281/zenodo.17230250
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This manuscript presents a rigorous analysis of the multi-scale dynamics of net ecosystem exchange (NEE) and its environmental drivers in the Pantanal, a region undergoing significant anthropogenic pressures from deforestation, agriculture, and the broader impacts of climate change. By leveraging high temporal resolution data, the authors quantitatively explore the interactions between carbon fluxes and environmental variables, contributing valuable insights to ongoing efforts in climate–ecosystem modelling.
The methodological framework is sound and well justified. The authors employ Detrended Cross-Correlation Analysis (DCCA) to investigate the scale-dependent relationships between NEE and key climatic drivers. This approach has been widely used and validated in various contexts, and its application here is both appropriate and effective. The paper is clearly structured, with coherent progression from methods to results and a balanced, thoughtful interpretation. The quality of writing is excellent—precise, fluent, and engaging—making this an enjoyable and informative read. The attention to detail throughout is commendable.
Detrended Cross-Correlation Analysis (DCCA) Findings
The DCCA results reveal a nuanced picture of carbon–climate interactions across temporal scales:
Conclusions on Carbon Flux–Climate Interactions
The study compellingly demonstrates that carbon flux–climate relationships in the Pantanal are strongly scale-dependent.
Overall Assessment
This is a well-executed and insightful study that enhances our understanding of carbon–climate coupling in floodplain ecosystems. The analytical approach is robust, the interpretations are well grounded in the data, and the broader implications are clearly articulated. The findings also open avenues for comparative analyses in drier and semi-arid ecosystems, where water-use efficiency and carbon–water coupling dynamics are more pronounced. Such extensions would be valuable for testing the generality of the patterns identified here.
In conclusion, this manuscript makes a substantial and well-argued contribution to ecosystem and climate science. I commend the authors for their meticulous work and recommend the paper for publication with only minor revisions:
Line 370 – revisit this section as these details have already been provided in lines 357 and 356
It would be great to include a map of the site, and a picture of the site set up as an insert – preferably.