New Guinea mangroves

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.

The Central African mangroves form the largest area of mangrove swamp in Africa, fringing the Atlantic coast and river mouths from Ghana and Nigeria south through Cameroon, Equatorial Guinea, Gabon, the Democratic Republic of the Congo, and Angola, with its greatest extent on the Niger Delta. These tidal forests are dominated by red mangroves of the genus Rhizophora (including Rhizophora racemosa and Rhizophora harrisonii), the black mangrove Avicennia germinans, and the white mangrove Laguncularia racemosa, with trees reaching up to 45 meters tall in fertile rivermouths and lagoons. The climate is humid and tropical where warm seas and high tides flood into the rivers, grading toward cooler, more temperate conditions in the south, and rainfall spans a wide gradient from a mean of about 750 mm in Angola to roughly 6,000 mm in Cameroon. The mangroves shelter rich communities of oysters, crabs, fish, and birds and support the threatened African manatee and turtles such as the African softshell, with the Sclater's guenon recognized as the ecoregion's flagship species; however, decades of Niger Delta oil spills and clearing for urban and industrial development have heavily degraded the habitat. The introduced Asian palm Nypa fruticans has also spread here as an invasive.

The East African mangroves fringe the Indian Ocean coast of southern Somalia, Kenya, Tanzania, and Mozambique, with their most extensive stands concentrated in the Rufiji River Delta of Tanzania and the Zambezi River Delta of Mozambique, where they can reach as far as 50 km inland. These tidal forests are built from salt-tolerant trees including Avicennia marina, Rhizophora mucronata, Sonneratia alba, Bruguiera gymnorrhiza, Ceriops tagal, and Xylocarpus granatum, growing as tall as 30 meters in the richest deltas. The climate is governed by the seasonal Northeast and Southeast monsoons and strong coastal currents, with rainfall heaviest in southern Kenya and northern Tanzania. Exceptionally productive, the ecoregion acts as a nursery for fish, shrimp, crabs, and molluscs and shelters dugongs, breeding sea turtles, and migratory shorebirds, yet mangroves are among the most critically threatened ecosystems in the world, lost to clearance for aquaculture, salt pans, and farmland as well as rising seas.

The Guinean mangroves form a band of coastal mangrove swamp along the rivers and estuaries of West Africa, spanning the shorelines of Senegal, Gambia, Guinea-Bissau, Guinea, Sierra Leone, and Liberia (with stands reaching into Côte d'Ivoire). The forest is built from salt-tolerant mangrove trees in the genera Rhizophora and Avicennia alongside Laguncularia racemosa and Conocarpus erectus, with the tallest trees reaching about 40 meters to form gallery forests along the creeks while inland fringes give way to grasses, ferns, and other salt-loving plants. The climate is strongly seasonal, alternating wet and dry periods, and rainfall varies enormously across the range, from very dry conditions in the Senegal River delta to some of the wettest coastline in Africa near Sierra Leone. Its flagship animal is the West African manatee, and Guinea-Bissau holds one of the largest populations of this elusive sirenian on the continent. The mangroves are a vital nursery for fish, shrimp, oysters, and waterbirds such as herons, flamingos, and the African spoonbill, but they are increasingly cleared for rice farming, firewood, and coastal development.

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.