What Is a Wetland?

Wetlands are transitional zones between terrestrial and aquatic environments, characterised by waterlogged soils, adapted vegetation, and unique hydrology. They are classified into four main types: marshes (dominated by grasses and reeds, like the Everglades), swamps (forested, like the Okefenokee or mangrove swamps), bogs (acidic, peat-forming, rain-fed, like Sphagnum bogs), and fens (alkaline, groundwater-fed). Though wetlands cover only about 5-8% of Earth land surface, they provide ecosystem services far beyond their size: they filter pollutants from water (a single hectare of wetland can filter millions of litres per year), store floodwaters (reducing downstream flooding), sequester carbon (peatlands store about twice as much carbon as all forests combined), and support extraordinary biodiversity (about 40% of all species depend on wetlands at some point in their life cycle). Despite their value, about 35% of wetlands have been lost since 1970.