What Are Wetlands?
Wetlands are areas where water covers the soil — either permanently or seasonally — creating unique conditions that support highly specialised communities of plants and animals. The category encompasses an extraordinary variety of habitats, from vast tropical swamps and temperate river floodplains to coastal salt marshes, peatlands, and mangroves.
Despite their diversity, all wetlands share a defining characteristic: water is the dominant force shaping their ecology, chemistry, and the organisms that inhabit them.
Types of Wetlands
| Type | Key Features | Example Locations |
|---|---|---|
| Peatlands / Bogs | Acidic, nutrient-poor; dominated by sphagnum moss; massive carbon stores | Scotland, Scandinavia, Canada |
| Marshes | Shallow, productive; dominated by reeds and grasses; rich wildlife | The Florida Everglades, Danube Delta |
| Mangroves | Coastal; salt-tolerant trees; nursery habitat for marine species | Southeast Asia, West Africa, Amazon coast |
| Floodplains | Seasonally inundated river margins; fertile soils; high biodiversity | Amazon, Mekong, Rhine |
| Fens | Nutrient-rich; fed by groundwater; support specialist plant communities | East Anglia (UK), Baltic region |
Why Wetlands Matter
Biodiversity Hotspots
Wetlands support a disproportionate share of global biodiversity relative to their area. They are critical feeding, breeding, and overwintering habitat for enormous numbers of birds — particularly migratory waterbirds — as well as amphibians, fish, reptiles, and countless invertebrates. Freshwater ecosystems, many of them wetland-associated, are home to a significant proportion of all described fish species.
Water Purification
Wetlands function as natural water filters. Plants and soils trap sediment, absorb excess nutrients (particularly nitrogen and phosphorus from agricultural runoff), and break down pollutants. Coastal wetlands like salt marshes and mangroves protect shorelines and adjacent marine ecosystems from nutrient pollution.
Flood Regulation
By absorbing and slowly releasing water, wetlands act as natural sponges, buffering against both floods and droughts. A single hectare of wetland can store millions of litres of floodwater, protecting downstream communities. The loss of floodplain wetlands has been linked directly to increased flood severity in many river catchments worldwide.
Carbon Storage
Peatlands are particularly remarkable carbon stores. Although they cover only around 3% of Earth's land surface, peatlands store roughly twice as much carbon as all the world's forests combined — locked up in slowly accumulating layers of partially decomposed organic matter built up over thousands of years. When peatlands are drained, this carbon is rapidly released as CO₂.
The Scale of Wetland Loss
Despite their value, wetlands have been drained, filled, and degraded at an alarming rate over the past century — primarily for agriculture, urban development, and flood control. Many countries have lost the majority of their original wetland area. This loss has driven widespread declines in wetland-dependent species and removed crucial ecosystem services from landscapes.
Wetland Restoration: A Reason for Hope
The good news is that wetlands can be restored, and they respond relatively quickly when conditions are right. Blocking drainage ditches in peatlands, re-meandering straightened rivers, and restoring tidal flow to reclaimed coastal marshes are all proven techniques that can return wetland habitats and their wildlife within years to decades. Restored wetlands deliver multiple co-benefits — for biodiversity, carbon storage, flood management, and water quality — making them among the most cost-effective conservation investments available.