Contribution to the ecological study of orchids in the Comoros archipelago: floristic diversity, biogeography, ecological status, and conservation challenges

The Malagasy biogeographical region, which includes the Comoros archipelago, is known worldwide for its natural wealth and as a biodiversity hotspot. The degradation of natural ecosystems threatens certain specialized species, including orchids. The aim of this study was to determine the diversity, assess the biogeography, and evaluate the ecological status of orchid species in the Comoros archipelago based on literature reviews, supplemented by field surveys and the application of IUCN criteria (version 4.0). The results of this study identified 148 species, subspecies, and varieties distributed across 33 genera. The endemism rate is 47%, with 63% being native. Grande Comore is the island with the highest number of endemic species (7 strictly endemic species). This flora has a closer affinity with Madagascar (47%) than with other neighboring countries: (3%) with the African continent, (1%) with Asia, or (2%) with the Mascarene Islands. Fifteen species are critically endangered (CR) (8%), seven are endangered (EN) (5%), 27 are vulnerable (VU) (16%), nine are near threatened (NT) (6%), 27 are of least concern (LC) (18%), and 68 are data deficient (DD) (46%). As part of the implementation of a biodiversity conservation management policy, measures must be taken quickly by local authorities to ensure the conservation of these species, some of which are endangered.