Comparative Mangrove Floristics of the Lower Mekong: Species Composition and Conservation Status in Cambodia, Thailand, and Vietnam

Abstract The Lower Mekong region, comprising Cambodia, Thailand, and Vietnam, forms a critical biogeographic transition zone supporting distinct yet interconnected mangrove floras. This comparative review synthesizes patterns of species diversity, composition, and conservation status across the three nations. Thailand’s Andaman coast emerges as a global biodiversity hotspot with the highest richness (~70 species), while Vietnam’s extensive coastline exhibits a deltaic mosaic altered by widespread monoculture planting. Cambodia, with lower overall richness (~25–30 species), hosts populations of high conservation value, including significant stands of the threatened Heritiera littoralis. Critically endangered species such as Bruguiera hainesii persist primarily in Thailand, underscoring the need for transboundary collaboration. Divergent biogeographic histories, environmental gradients, and anthropogenic pressures have shaped these distinct floristic assemblages. Effective regional conservation requires a complementary strategy: Thailand safeguarding species richness, Cambodia protecting genetic reservoirs of wide-ranging threatened taxa, and Vietnam integrating biodiversity into its vast restored landscapes. A coordinated regional approach is essential to preserve the full spectrum of mangrove diversity and enhance ecosystem resilience under climate change. Keywords: Mangrove biodiversity; Lower Mekong region; Floristic comparison; Species richness; Vietnam Mekong Delta; Cambodia; Transboundary conservation