Where the story began
In late 2016, a single question sparked my scientific journey: Why don't mangroves extend to higher latitudes? After reading the paper "A World Without Mangroves?", I couldn't stop thinking about how these threatened ecosystems develop and how we might monitor this effectively. What followed was a chain reaction of unexpected academic connections. My literature search led me to a conference paper by Valéry Gond. I reached out to him, and what began as a non-binding exchange evolved into a long-lasting collaboration. In a twist of academic fate, Valéry recognized the foundational work of Uta Berger, one of the authors who had originally inspired me in 2016, and invited her to join the RESCuE project. Valéry and Uta would later become my PhD supervisors. Over the years, this collaborative ecosystem allowed us to develop an approach to understanding the complex links between mangrove composition and landscape recovery. This methodological foundation directly steered my doctoral and postdoctoral research, ultimately paving the way for our present study in southern Thailand. Yet, looking at mangroves required a shift in perspective. Before diving into the coastlines, I had crossed paths with Dario Simonetti while researching terrestrial forests. Dario’s enthusiasm for Earth observation taught me to look beyond standard remote sensing pixels. He challenged me to ask deeper ecological questions from space, a shared curiosity that ultimately anchors the work presented here.
Science built through strong collaboration and friendships
As our methodological framework took shape, our roots in Thailand deepened. Scientific breakthroughs rarely happen in a vacuum, and our work found its footing through a succession of crucial national and local partnerships. I first crossed paths with Sukan Pungkul, who generously bridged the gap to Kumron Leadprathom. Kumron’s local roots in Trat, interest in ecology and commitment to helping his community helped us build trust and involve local people in our research. This trust soon expanded. Supported by Tamanai Pravinvongvuthi, Anuchit Jaikuea, Ruchakorn Tanasomboonpan, and Thanakrit Bunkoed from the Department of Marine and Coastal Resources (DMCR), our ambitious plans materialized into a massive reality: establishing more than 250 field plots across Trat Province. When our focus expanded to southern Thailand during the RESCuE-2 phase, our academic family grew to include Ruth Phatanacharoen, Poonsri Wanthongchai, Sumet Thongdon-um, and Asamaporn Sitthi. Fieldwork in dense mangrove forests is notoriously unforgiving, yet local DMCR colleagues Pasaet Jinda and Wichan Wannachit managed to turn even the most challenging days into moments of shared joy. From local community leaders and expert boat drivers to the residents who welcomed us, their knowledge, effortless hospitality, and profound care formed the true backbone of our fieldwork. They did not just support our research; they made it possible.
Serious fieldwork and a little craziness
Heat, mud, tangled roots, insects and venomous snakes tested both physical and mental endurance. It takes preparation, determination and perhaps a little craziness. We still remember our first long transect in eastern Thailand. The boats reached the planned location, Valéry stepped into the water, and the rest of us followed. Completing 2.4 kilometers took two demanding days. It helped us understand how mangrove structures change across the landscape, and why satellite-based analysis needs carefully planned field surveys. For the current study in Phang Nga, we established 183 plots, recording 4,419 trees and their structural characteristics. The campaign was not without its costs; some moments brought serious accidents and injuries that tested our limits, while others became stories we still laugh about. Getting through those difficult days brought us closer, and we learned to look after one another.
A recovery story we did not expect
When we began this study, we did not know what story the landscape would reveal. The area had experienced decades of tin mining, charcoal concessions, and shrimp farming. Reconstructing its history from 1966 to 2025 revealed both loss and recovery. Natural regeneration accounted for more than 90% of the mangrove gain between 1987 and 2025. Field surveys brought another surprise: naturally regenerated forests where mature trees remained supported tree species diversity comparable to natural forests. Coupled with our previous observations in eastern Thailand, these findings made us question how restoration success is measured. Counting surviving planted trees or observing a greener landscape does not tell us whether biodiversity has recovered. Before planting, we need to understand the landscape’s history even before satellite records began- what remains, and whether natural recovery is already underway.
The Xylocarpus paradox
One unexpected finding concerned Xylocarpus granatum. Many large trees appear to have survived earlier disturbances, remaining as biological legacies. Although the species accounted for only one-tenth of recorded stems, these trees contributed disproportionately to forest structure. Although the species accounted for only one-tenth of recorded stems, these large trees contributed disproportionately to forest structure. We called this the “Xylocarpus paradox”. They occurred across natural and regenerated forests, often alongside locally rare species, and may help create conditions for other species to return. This changed how we thought about recovery: it does not always begin with an empty landscape. The trees left behind may help shape what grows next.
Conservation beyond protected boundaries
Although outside a formally protected area, these mangroves have persisted through national policies, government management, and local community participation. This led us to consider the landscape as a potential Other Effective area-based Conservation Measure (OECM): an area that sustains biodiversity outside formal protected areas. We found evidence of long-term ecological persistence and functioning governance, but formal recognition would require national evaluation and continued engagement with local communities. Our study provides evidence for that assessment, not a designation. Similar landscapes may remain overlooked across Southeast Asia and elsewhere because their ecological histories have not been examined.
Beyond this paper
Our first responsibility is to share these findings with the agencies and communities managing this landscape. We hope the work helps identify potential OECMs and guides decisions about where planting is needed and where natural recovery can be supported. For us, this paper reflects nearly a decade of curiosity, difficult fieldwork, and friendships across countries and communities. Just as these forests did not recover through a single intervention, this research was not the work of one person. Both took time, persistence, and support from what was already there.