Wetland
A wetland is an ecosystem where water shapes the soil, plants, and wildlife. Wetlands include marshes, swamps, bogs, fens, and coastal wetlands that store floodwater, filter pollution, support biodiversity, and connect land with water.
What a wetland is
A wetland is a place where water is present often enough to create wet soils and support plants adapted to saturated conditions. Some wetlands are visibly flooded much of the year. Others may look dry during part of the season but still have the hydrology, soils, and vegetation that mark them as wetlands.
Water, soil, and plants
Wetlands are shaped by hydrology. When soil stays saturated, oxygen becomes limited and chemical conditions change. Plants that survive there often have special structures or growth habits that help them cope with flooding, low oxygen, salinity, or repeated changes between wet and dry conditions.
Marshes, swamps, bogs, and fens
Wetlands are not all the same. Marshes are usually dominated by grasses, sedges, reeds, or other herbaceous plants. Swamps have trees or shrubs. Bogs often accumulate peat and receive most water from precipitation, while fens receive mineral-rich groundwater or surface water. Coastal wetlands include salt marshes and mangroves.
Flood storage and flow
Many wetlands work like landscape sponges. They can store rain, snowmelt, groundwater, or floodwater, then release it more slowly. This can reduce flood peaks, maintain streamflow during dry periods, and slow storm surge or waves along some coasts, depending on location, size, vegetation, and connectivity.
Water quality
Wetlands can trap sediment, take up nutrients, transform some pollutants, and slow runoff long enough for particles to settle. Their soils, roots, microbes, and plant litter all contribute. They are valuable filters, but they can be overloaded by too much pollution, altered water flow, invasive species, or development.
Habitat and food webs
Wetlands are nurseries, feeding grounds, nesting sites, and migration stops for many fish, birds, amphibians, reptiles, insects, and mammals. Seasonal wetlands such as vernal pools can support species that depend on temporary water because fish predators are absent or reduced.
Carbon and climate
Peatlands, mangroves, salt marshes, and seagrass-related coastal systems can store large amounts of carbon in wet soils. When wetlands are drained, burned, or eroded, stored carbon can be released. Protection and restoration can therefore be part of climate strategy, though methane emissions and local conditions complicate accounting.
Loss and restoration
Wetlands have been drained, filled, diked, farmed, mined, polluted, and disconnected from rivers and tides. Restoration may involve rewetting soil, removing barriers, rebuilding channels, controlling invasive species, replanting vegetation, or changing water management. Restored wetlands need time to regain structure and function.
Why it matters
Wetlands sit at the meeting point of land, water, and life. They are infrastructure, habitat, climate archives, cultural places, and buffers against extremes. Protecting them is often cheaper and more resilient than trying to rebuild every service they provide with concrete, pumps, filters, and emergency repairs.