The deterministic role of surface elevation in natural mangrove establishment and expansion : insight from Unmanned Aerial Systems /Staquet, Adrien /Proisy, Christophe Gardel, A. Augusseau, P. E. Maury, T. Attali, A. Brunier, G. Facundes, F. Frati, G. /Granjon, Laurent /Leroy, Céline /Mury, Antoine Santos, V. F. Anthony, E. J. Mangroves Muddy sedimentation UAS photogrammetry Mudflat elevation Ecological restoration Nature-based solution South America The role of substrate elevation in the establishment of mangroves has been highlighted in the literature. However, the link between elevation and mangrove growth over large areas remains poorly known. To address this issue, we conducted an experiment in French Guiana, where extensive mud banks provide large areas of accreting mudflats over which occurs rapid mangrove expansion. About 15 ha of a mudflat were topographically surveyed monthly to bimonthly over 19 months using Unmanned Aerial System (UAS)-based high-resolution photogrammetry, and environmental variables (vegetation, water depth, temperature, salinity) continuously measured. During the experiment, the mudflat elevation increased by 0.9 m, from 2.4 to 3.5 m above Lowest Astronomical Tide level, in the wake of mud-bank sedimentation. About 5.5 ha were colonised by Laguncularia racemosa and Avicennia germinans mangroves in less than 4 months. Once the elevation reached 2.8 m, close to Mean High Water Neaps, abundant seedlings rapidly established and spread. Therefore, mapping elevation using UAS-photogrammetry reveals how coastal accretion can trigger mangrove establishment. We discuss the advantages of this cost-effective tool in confidently identifying critical elevation levels for natural mangrove establishment and for viable mangrove restorations, many of which fail due to poor knowledge of substrate elevation. We show the limitations of photogrammetric surveys once the mangrove cover develops. Monitoring the link between mangrove establishment and elevation can provide essential insight in the anticipation of coastal change and in the successful implementation of mangrove-based ecological restoration. 2026 text https://www.documentation.ird.fr/hor/fdi:010097067 fdi:010097067 Staquet Adrien, Proisy Christophe, Gardel A., Augusseau P. E., Maury T., Attali A., Brunier G., Facundes F., Frati G., Granjon Laurent, Leroy Céline, Mury Antoine, Santos V. F., Anthony E. J.. The deterministic role of surface elevation in natural mangrove establishment and expansion : insight from Unmanned Aerial Systems. 2026, 337, 109903 [16 p.] EN GUYANE FRANCAISE CAYENNE