marsh

Marsh is a type of wetland characterized by saturated soils and shallow water, where herbaceous plants rather than trees and shrubs predominate. Soils are usually hydric and rich in nutrients. Marshes can be freshwater, brackish, or saline, and may be inland or coastal. Inland freshwater marshes form in depressions along rivers and lakes, while coastal marshes are typically fed by tides.

Vegetation commonly includes grasses, reeds, sedges, and rushes, such as cattails and bulrushes. In coastal marshes, halophytic grasses and forbs tolerate salt. The open water and emergent plants support diverse communities of birds, amphibians, insects, and aquatic invertebrates, and they play a key role in nutrient cycling and sediment stabilization.

Marshes provide several ecosystem services: flood attenuation, water purification by trapping sediments and pollutants, groundwater recharge, and carbon storage. They also contribute to biodiversity and support fisheries and recreation.

Threats include drainage, land reclamation, pollution, invasive species, and climate-related changes such as sea-level rise and altered hydrology. Loss or degradation of marshes can reduce flood protection and habitat value. Conservation and restoration efforts focus on reestablishing natural hydrology, controlling invasive species, and protecting surrounding landscapes. In many regions, marshes are managed within broader wetland or estuary programs, with recognition of both their ecological importance and their vulnerability to human activity.