Mangrove forests

Mangrove forests grow where land and sea meet, especially along sheltered tropical and subtropical coasts, estuaries and tidal waters. The word “mangrove” describes trees and shrubs adapted to salty or brackish conditions; these plants are not all close botanical relatives. Rather, their shared ecological setting and adaptations distinguish the group. The Smithsonian Ocean portal notes that mangroves can grow in salty, oxygen-poor soils within reach of the tides, and that their species differ in how scientists define a “true” mangrove.

Mangrove plants contend with salt, shifting sediment and waterlogged soils. Adaptations include ways of limiting salt uptake and root structures that anchor plants in unstable ground. Forests formed by these plants provide habitat for many organisms, including species associated particularly with mangrove environments. They also serve as nursery habitat for some commercially important fish and support people living near coasts through food and other resources. The precise mix of species and ecological functions varies among regions.

Mangroves can reduce exposure to coastal hazards: their forests help protect shorelines from storms, erosion and flooding. They are also one of the coastal ecosystems that store “blue carbon.” Carbon is held both in plant material and in soils, where coastal carbon can persist for long periods. When these habitats are damaged or destroyed, stored carbon may be released and the ecosystem's capacity to take up additional carbon is reduced. Mangroves also benefit adjacent ecosystems such as coral reefs and seagrass meadows.

Mangrove forests are found along coasts in 123 countries, according to UNEP. The Food and Agriculture Organization's 2023 account of its global assessment reported 14.8 million hectares worldwide in 2020. Between 2000 and 2020, 677,000 hectares were lost, while new forests established over 393,000 hectares in areas where mangroves had not been present in 2000; the rate of loss slowed in the second decade of that period. These are assessment-period figures, not a real-time estimate.

Pressures include conversion for aquaculture or agriculture, coastal development, overharvesting, pollution and climate-related changes such as sea-level rise and severe storms. The IUCN global Red List of Ecosystems assessment found that half of assessed mangrove ecosystem units were in categories at risk of collapse, representing half of global mangrove area in that assessment. Conservation responses include avoiding habitat loss, sustainable management, restoration and improved monitoring.