Starting a PhD in Eberswalde
As every PhD is supposed to be a daring academic endeavor, this one quite literally became a journey spanning thousands of kilometers. It started with me moving to Eberswalde, a town north of Berlin in October 2019. At the Eberswalde University for Sustainable Development, I began working on my PhD with the headline “Effectiveness of Biosphere Reserves” under the guidance of Pierre Ibisch. With several years of experience in multi-proxy analyses and biosphere reserve management, including the establishment of two research institutions, Pierre Ibisch supervised the development of a framework for evaluating the effectiveness of biosphere reserves through the use of satellite imagery. My first step in this project was to conduct a systematic literature review, a specialty of my co-supervisor Henrik von Wehrden at the Leuphana University in Lüneburg. This review became the introductory publication for my PhD, identifying the key aspects of remotely sensed protected area assessments.1
During the pandemic, I explored different ecosystem functioning variables. Pierre Ibisch and I gave special attention to the temperature regulating functioning of forest ecosystems. 2 Especially the work of Nathalie Pettorelli’s Lab of The Zoological Society of London2 was very informative for the selection of proxies I aspired to use in my PhD. Nathalie Pettorelli agreed to become part of the effectiveness assessments in Spring 2022. Aside the selection of suitable and relevant proxies of ecosystem functions, the collection of border data of the world network of biosphere reserves became a major effort. Together with colleagues at Eberswalde University we collected border information for the biosphere reserves which proved to be more difficult than expected, since demarcations changed over time and border data was not accessible for quite a few biosphere reserves.
While I relied on satellite data for global analyses, I was also fortunate to visit 25 biosphere reserves in person (some of them way before the start of my PhD). Though I didn’t use the visits for ground truthing, particularly two student excursions in 2020 and 2023 to the forest biosphere reserves in Ukraine and Romania provided valuable context for my remote sensing analyses.
Stopover at the Carbon Cycle and Ecosystems Group at the NASA Jet Propulsion Laboratory Pasadena, USA
Even more precious proofed to be a meeting in in early 2021 for another project on mapping biomass. There I got to know, Sassan Saatchi head of the Carbon Cycle and Ecosystems Group at the NASA Jet Propulsion Laboratory (JPL) in Pasadena, Los Angeles. As I knew right from the start of my PhD, that I wanted to gain international research experience, I asked Sassan Saatchi about the possibility of becoming a visiting scholar with his research group. His willingness to host me combined with the DAAD funding for international research stays for computer scientists opened the door for a six-month research stay in the Winter of 2022/23, that was an invaluable benefit to my research.
At JPL, I had the opportunity to see the latest work of satellite parts for the NISAR mission in the clean room at JPL and to learn about the work of my temporary colleagues at the carbon cycle and ecosystems group at JPL. I immersed myself in ecosystem functioning analyses using cloud computing platforms to process and filter data from the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Aqua and Terra satellites. Under the guidance of Sassan Saatchi’s Lab, I came to understand the need to go beyond a classification of “good” or “bad” biosphere reserves in terms of their ecosystem functioning but using the power of comprehensive datasets. I started collecting data for 119 biosphere reserves and their surroundings for two time periods and seven forest ecosystem function proxies, such as hot day temperature, gross primary productivity and forest patch connectivity.
Completing my PhD between Berlin and Lüneburg
Returning to Europe, I settled in Berlin, carrying with me nearly 8 million data points for 119 biosphere reserves and their surroundings worldwide. The subsequent phase of my research focused on statistical modeling, working closely with Henrik von Wehrden to implement mixed effect models to identify patterns in this vast dataset. During this time, I was also able to visit Nathalie Pettorelli in London. Together we validated my final selection of ecosystem functioning proxies and model adjustments. After that, the final manuscript of my PhD project circulated back and forth between Berlin, Eberswalde, Lüneburg, Los Angeles and London.
Before formally submitting my dissertation, I transitioned into a PostDoc position at Leuphana University in Autumn 2023, completing the journey that my thesis had done many times already. The publication process for my final PhD paper was not without its own challenges. But thanks to the helpful comments of three reviewers the paper was ultimately accepted in Nature Communications Earth & Environment.
In July 2024, I defended my PhD at the Leuphana University, marking the formal conclusion of this academic chapter. For me, though, the publication of the study on the effectiveness of biosphere reserves in maintaining forest ecosystem functions in January 2025 represents the real conclusion of this fabulous voyage.4
References
1 Gohr, C., von Wehrden, H., May, F., & Ibisch, P. L. (2022). Remotely sensed effectiveness assessments of protected areas lack a common framework: A review. Ecosphere, 13(4), e4053.
https://doi.org/10.1002/ecs2.4053
2 Gohr, C., Blumröder, J. S., Sheil, D., & Ibisch, P. L. (2021). Quantifying the mitigation of temperature extremes by forests and wetlands in a temperate landscape. Ecological Informatics, 66, 101442. https://doi.org/10.1016/j.ecoinf.2021.101442
3 Pettorelli, N., Schulte to Bühne, H., Tulloch, A., Dubois, G., Macinnis‐Ng, C., Queirós, A. M., ... & Nicholson, E. (2018). Satellite remote sensing of ecosystem functions: opportunities, challenges and way forward. Remote Sensing in Ecology and Conservation, 4(2), 71-93. https://doi.org/10.1002/rse2.59
4 Gohr, C., von Wehrden, H., Saatchi, S., Pettorelli, N. & P. L. Ibisch (2025). Effectiveness of the world network of biosphere reserves in maintaining forest ecosystem functions. Commun Earth Environ 6, 83. https://doi.org/10.1038/s43247-025-02081-y