Radiometric landscapes of the Kerguelen Islands using moderate resolution data and unsupervised clustering methods
Résumé
Characterize and delineate spatiotemporal radiometric landscapes (i.e. RadLand) of the Kerguelen Archipelago (Sub-Antarctica, South Indian Ocean) using MODIS NDVI time series, while considering for both seasonal and multiyear variations. Test the relevance of the RadLand identified using MODIS data in relation to biodiversity, and thereby highlighting the differences in vegetation dynamics across the landscapes. Map the landscapes of the archipelago and assess the influence of topographic metrics (slope, elevation, orientation) in defining landscape contexts, integrating these factors into the analysis of landscape units. Medium-resolution data has proven effective in detecting and identifying landscape with Object-Based Image Analysis (OBIA) and classification applied to types across the Kerguelen Islands. The multi-temporal analysis of the NDVI index, considering both seasonal and multi-year variations, has enhanced the accuracy of segmentation results, particularly in the delineation of RadLand. Topographic metrics and NDVI DHI analysis revealed the spatio-temporal diversity between the eastern and western landscapes, enhancing different ecological contexts. RadLand 1 is a type of coastal landscape characterized by vegetated cliffs with low temporal dynamics. RadLand 2 and 4 are transitional landscapes with contrasting topography, found at mid-level altitudes, influenced by surface temperature variations. RadLand 3 is a high-altitude landscape, primarily characterized by mineral surface features. RadLand 5, on the other hand, is a vegetated plain landscape, mainly found in the eastern part of the Kerguelen Islands.
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