École Nationale Supérieure de
Techniques Avancées

Résumé

Mangroves, despite their harsh high-salinity and flooded environment, are amongst the most productive ecosystems of the world and provide numerous benefits to both the environment and local populations. Yet, the 150,000 km² they cover today suffered a 20% surface loss between 1980 and 2005 and, even if the deforestation rate has decreased, they are still threatened, essentially by human activities and climate change. Including mangroves in land models such as ORCHIDEE could bring necessary information on their future evolution that would benefit to the protection of these unique ecosystems. Here we explored the possibilities offered by satellite imagery and especially the high resolution Sentinel-2 satellites. We developed a method for mangrove cartography based on spectral characteristics of the mangrove trees and tested it in Martinique, showing consistent result. We also highlighted an annual cycle based on vegetation indexes from satellite images. We thus showed that vegetation activity is at its maximum after the rain season, corresponding to the minimum hydric stress applied on the trees.