Sunda Shelf mangroves

The Indochina mangroves fringe the tropical coasts of the Gulf of Thailand across Thailand, Cambodia, Vietnam, and into Malaysia, with their largest surviving stands in the Mekong Delta of southern Vietnam. These are classic tidal mangrove forests shaped by regular flooding with brackish and saltwater, where vegetation sorts itself by salinity: pioneer Avicennia alba lines the open shore, giving way inland to Rhizophora apiculata and Bruguiera parviflora, while less-salty freshwater zones support Avicennia officinalis, Sonneratia caseolaris, and the palms Nypa fruticans and Phoenix paludosa. The estuarine, or saltwater, crocodile is the flagship species, and the remaining forests shelter rare waterbirds including the lesser adjutant, white-winged wood duck, and spot-billed pelican. Much of this habitat has been lost, however, from wartime defoliation of the Mekong Delta to ongoing conversion into shrimp ponds, so very little of the ecoregion is formally protected. For gardeners, the native mangrove palm Nypa fruticans is a notable horticultural relative of the broader Indomalayan palm flora.

This mangrove ecoregion fringes the Arabian Sea coast of Sindh Province in Pakistan, where the Indus River builds a vast alluvial delta, and extends to the Gulfs of Kutch and Khambhat in Gujarat, India. Its forests are overwhelmingly dominated by the grey or white mangrove (Avicennia marina), a species that tolerates exceptionally high salinity, with red mangrove (Rhizophora mucronata) and Indian mangrove (Ceriops tagal) appearing on small patches of higher ground. The climate is harsh and arid, swinging from near-freezing winters to summer temperatures around 50 degrees Celsius, with most rain confined to the southwest monsoon between July and September and very high evaporation that keeps the tidal flats intensely saline. These mangroves form one of the world's largest such forests and serve as a critical staging area for tens of thousands of migratory birds, including greater flamingos and the ecoregion's flagship Dalmatian pelican. The habitat faces serious pressure from reduced Indus freshwater flow, pollution and oil spills near Karachi, and cutting for fuelwood and grazing.

The Myanmar Coast mangroves fringe the eastern rim of the Bay of Bengal, spanning Myanmar, Bangladesh, Thailand, and Malaysia, with the richest concentrations in Myanmar's Ayeyarwady (Irrawaddy) delta and the Rakhine and Tanintharyi coasts. These tidal forests are dominated by classic Indo-Pacific mangrove genera such as Rhizophora, Bruguiera, Sonneratia, Avicennia, and Xylocarpus, alongside the nipa palm (Nypa fruticans) and the mangrove date palm (Phoenix paludosa). The setting is built on alluvial silt deposited by the Ayeyarwady, one of the world's most sediment-laden rivers, whose delta is composed largely of washed-down alluvium. Notably, the ecoregion holds one of the highest mangrove-tree species richnesses of any mangrove region in the Indian Ocean and serves as habitat for the critically endangered four-toed terrapin (Batagur baska), its flagship species. It is also one of Asia's most depleted mangrove areas, heavily reduced by logging and conversion to agriculture, making the surviving forests a conservation priority. For gardeners, the palms native here, the nipa and the mangrove date palm, are striking tropical, salt- and water-tolerant ornamentals.

The Sundarbans mangroves form the world's largest contiguous mangrove forest, spanning the lower Ganges-Brahmaputra-Meghna delta across southern Bangladesh and the Indian state of West Bengal. The forest is dominated by the sundri tree (Heritiera fomes), from which it takes its name, alongside other salt-tolerant genera including Avicennia, Sonneratia, Xylocarpus, Bruguiera, Ceriops, and Rhizophora, with the nipa palm (Nypa fruticans) lining its tidal creeks. Its climate is governed by strong monsoons off the Bay of Bengal that deliver heavy rainfall and intense daytime heat, punctuated by destructive cyclones. The ecoregion is the only mangrove system that sustains a viable population of the Bengal tiger, which swims among its islands, and its protected areas are inscribed as a UNESCO World Heritage Site. Gardeners drawn to its flora will recognize coastal genera such as Sonneratia and the architectural nipa palm, both native to these intertidal forests.

The Amazon-Orinoco-Southern Caribbean mangroves form a vast coastal ecoregion in the Neotropics, fringing the Caribbean shores of Colombia and Venezuela and the Atlantic coasts of Venezuela, Guyana, Suriname, French Guiana, and northeastern Brazil, including the Brazilian states of Amapá, Pará, and Maranhão. Shaped by the outflow of the Amazon and Orinoco rivers, its tidal wetlands are dominated by salt-tolerant mangroves such as Rhizophora racemosa and Avicennia schaueriana, alongside green buttonwood and the familiar red, white, and black mangroves. The climate is equatorial and fully humid, with year-round warmth roughly between 22 and 31 degrees Celsius and abundant rainfall averaging around 2,500 millimetres annually. These constantly flooded forests shelter rich birdlife and wildlife, from the scarlet ibis and American flamingo to giant otters, manatees, and nesting sea turtles, and the ecoregion's flagship is the critically endangered sapphire-bellied hummingbird. Though much of it remains relatively intact, mangrove stands here face mounting pressure from urbanization, pollution, and timber extraction.

The Bahamian-Antillean mangroves form a Neotropical mangrove ecoregion scattered across the islands of the Caribbean and the western Atlantic, spanning jurisdictions that include Cuba, The Bahamas, Hispaniola (Haiti and the Dominican Republic), Jamaica, Puerto Rico, the Turks and Caicos, the Cayman Islands, and the US Virgin Islands. Its tidal forests are built from four characteristic salt-tolerant trees: red mangrove (Rhizophora mangle), black mangrove (Avicennia germinans), white mangrove (Laguncularia racemosa), and buttonwood (Conocarpus erectus). The climate is subtropical and strongly hurricane-exposed, with rainfall declining from the wetter northern islands toward the drier south. These shallow-water forests shelter notable wildlife, serving as habitat for West Indian manatees, marine turtles, and American flamingos, with the Northern Bahamian rock iguana recognized as the ecoregion's flagship species. Coastal tourism development and sea-level rise are leading threats, which matters to gardeners because buttonwood (Conocarpus) native here is among the region's hardiest salt- and wind-tolerant coastal plants.