PhD project offered by the IMPRS-gBGC in July 2026

Linking Forest Biomass Dynamics and Atmospheric Inversions in the Amazon rainforest

Santiago Botía , Gregory Duveiller , Alexander Brenning

Project description

The Amazon forest plays a critical role in the global carbon cycle, yet large uncertainties persist in estimates of its net carbon balance. A key source of these uncertainties is the mismatch between bottom-up process-based models and top-down atmospheric inversions, which often disagree in both the magnitude and spatial distribution of carbon fluxes (Rosan et al., 2024, Botía et al., 2025). Compounding this challenge, recent radar-based remote sensing analyses have documented negative long-term trends in Amazonian aboveground biomass (AGB), which have been linked to drought-induced defoliation, branch fall, or tree mortality (Tao et al., 2025, Bai et al,. 2026). Understanding the drivers and spatial structure of these trends is therefore essential for reconciling biomass changes and top-down carbon flux estimates across the region.

This PhD project will investigate the spatial and temporal variability of AGB across the Amazon basin using multi-source remote sensing data, with the goal of identifying key regions and timescales of biomass change that can be linked to high-resolution regional atmospheric CO₂ inversion outputs. In a first step, the candidate will characterize AGB trends across multiple datasets, assessing their consistency and identifying regions of robust positive or negative change. For areas exhibiting negative trends, the project will examine a set of candidate drivers, including windthrow events and convective storm damage hotspots (Urquiza-Muñoz et al., 2024), forest degradation, and increasing drought frequency. Where positive trends emerge, if any, the analysis will turn to the role of governance, specifically, why indigenous territories and protected national parks consistently show higher AGB density, and how these contexts modulate forest resilience and post-disturbance recovery trajectories.

In a second step, the student will leverage these spatially explicit AGB dynamics to interpret outputs from a high-resolution regional atmospheric inversion system (Botía et al., 2025). By identifying regions and timescales of high AGB change and cross-comparing them with inversion-derived source and sink patterns, the student will assess whether biomass dynamics are detectable in the atmospheric signal, and deepen understanding of how biomass change and forest age relate to net carbon exchange, extending recent efforts conducted at coarser and global resolution (Besnard et al., 2025) to the regional scale. The outcomes of this project will provide new constraints on the contribution of forest disturbance and recovery to the Amazon carbon balance, advance understanding of the timescales over which biomass dynamics translate into atmospheric CO₂ signals, and contribute to improved integration of remote sensing and inversion-based carbon flux products at regional scale.

Working group

The candidate will be part of the Biogeochemical Signals and Integration departments and will have the opportunity to collaborate with other researchers from multiple institutions in Brazil, Colombia, Perú and Germany.

Requirements

Applications to the IMPRS-gBGC are open to well-motivated and highly-qualified students from all countries. Prerequisites for this PhD project are:

Master’s degree in environmental sciences, geography, physics, geosciences, ecology, atmospheric science, remote sensing, engineering, or related fields.
Background in ecosystem carbon cycling, windthrows, forest ecology, land–atmosphere interactions, and/or biogeochemistry.
Experience with remote sensing datasets (e.g., radar-based biomass products, Landsat, optical time series) is strongly valued.
Strong computational and analytical skills.
Experience with programming languages such as Python, R, and/or Julia.
Familiarity with spatial analysis tools and gridded environmental datasets (e.g., climate reanalyses, land cover products).
Excellent written and oral communication skills in English.
Knowledge of Spanish or Portuguese is beneficial.

The Max Planck Society (MPS) strives for gender equality and diversity. The MPS aims to increase the proportion of women in areas where they are underrepresented. Women are therefore explicitly encouraged to apply. We welcome applications from all fields. The MPS has set itself the goal of employing more severely disabled people. Applications from severely disabled persons are expressly encouraged.

References

H. Bai, X. Liu, H. Yang, J. Chave, P. Ciais, J. Wigneron, S. Saatchi, J. Xiao, T. Le Toan, X. Hu, Z. Yang, L. Wang, L. Fan, Y. Yao, X. Chen, Y. Liu, B. Xue, Q. Guo, Z. Tang, H. Liu, J. Fang, & S. Tao, Unprecedented Amazonian rainforests damage during the 2023–2024 droughts, Proc. Natl. Acad. Sci. U.S.A. 123 (13) e2514066123, https://doi.org/10.1073/pnas.2514066123 (2026).

Besnard, S., Heinrich, V.H.A., Carvalhais, N. et al. Global covariation of forest age transitions with the net carbon balance. Nat Ecol Evol 9, 1848–1860 (2025). https://doi.org/10.1038/s41559-025-02821-5

Botía, S., Munassar, S., Koch, T., Custodio, D., Basso, L. S., Komiya, S., Lavric, J. V., Walter, D., Gloor, M., Martins, G., Naus, S., Koren, G., Luijkx, I. T., Hantson, S., Miller, J. B., Peters, W., Rödenbeck, C., and Gerbig, C.: Combined CO2 measurement record indicates Amazon forest carbon uptake is offset by savanna carbon release, Atmos. Chem. Phys., 25, 6219–6255, https://doi.org/10.5194/acp-25-6219-2025, 2025.

S. Tao, J. Chave, P. Frison, T. Le Toan, P. Ciais, J. Fang, J. Wigneron, M. Santoro, H. Yang, X. Li, N. Labrière, & S. Saatchi, Increasing and widespread vulnerability of intact tropical rainforests to repeated droughts, Proc. Natl. Acad. Sci. U.S.A. 119 (37) e2116626119, https://doi.org/10.1073/pnas.2116626119 (2022).

Rosan, T.M., Sitch, S., O’Sullivan, M. et al. Synthesis of the land carbon fluxes of the Amazon region between 2010 and 2020. Commun Earth Environ 5, 46 (2024). https://doi.org/10.1038/s43247-024-01205-0

Urquiza-Muñoz, J. D., Trumbore, S., Negrón-Juárez, R. I., Feng, Y., Brenning, A., Vasquez-Parana, C. M., & Magnabosco Marra, D. (2024). Increased occurrence of large-scale windthrows across the Amazon basin. AGU Advances, 5, e2023AV001030. https://doi.org/10.1029/2023AV001030