Publications des scientifiques de l'IRD

Taureau F., Robin M., Proisy Christophe, Fromard F., Imbert D., Debaine F. (2019). Mapping the mangrove forest canopy using spectral unmixing of very high spatial resolution satellite images. Remote Sensing, 11 (3), art. 367 [17 p.]. ISSN 2072-4292.

Titre du document
Mapping the mangrove forest canopy using spectral unmixing of very high spatial resolution satellite images
Année de publication
2019
Type de document
Article référencé dans le Web of Science WOS:000459944400155
Auteurs
Taureau F., Robin M., Proisy Christophe, Fromard F., Imbert D., Debaine F.
Source
Remote Sensing, 2019, 11 (3), art. 367 [17 p.] ISSN 2072-4292
Despite the low tree diversity and scarcity of the understory vegetation, the high morphological plasticity of mangrove trees induces, at the stand level, a very large variability of forest structures that need to be mapped for assessing the functioning of such complex ecosystems. Fully constrained linear spectral unmixing (FCLSU) of very high spatial resolution (VHSR) multispectral images was tested to fine-scale map mangrove zonations in terms of horizontal variation of forest structure. The study was carried out on three Pleiades-1A satellite images covering French island territories located in the Atlantic, Indian, and Pacific Oceans, namely Guadeloupe, Mayotte, and New Caledonia archipelagos. In each image, FCLSU was trained from the delineation of areas exclusively related to four components including either pure vegetation, soil (ferns included), water, or shadows. It was then applied to the whole mangrove cover imaged for each island and yielded the respective contributions of those four components for each image pixel. On the forest stand scale, the results interestingly indicated a close correlation between FCLSU-derived vegetation fractions and canopy closure estimated from hemispherical photographs (R-2 = 0.95) and a weak relation with the Normalized Difference Vegetation Index (R-2 = 0.29). Classification of these fractions also offered the opportunity to detect and map horizontal patterns of mangrove structure in a given site. K-means classifications of fraction indeed showed a global view of mangrove structure organization in the three sites, complementary to the outputs obtained from spectral data analysis. Our findings suggest that the pixel intensity decomposition applied to VHSR multispectral satellite images can be a simple but valuable approach for (i) mangrove canopy monitoring and (ii) mangrove forest structure analysis in the perspective of assessing mangrove dynamics and productivity. As with Lidar-based surveys, these potential new mapping capabilities deserve further physically based interpretation of sunlight scattering mechanisms within forest canopy.
Plan de classement
Etudes, transformation, conservation du milieu naturel [082] ; Télédétection [126]
Description Géographique
GUADELOUPE ; MAYOTTE ; NOUVELLE CALEDONIE
Localisation
Fonds IRD [F B010075283]
Identifiant IRD
fdi:010075283
Contact