They often feature evergreen trees and shrubs and the floor of a bog is often covered with a thick carpet of sphagnum moss. Fens receive water from groundwater sources. They are not acidic and have higher nutrient content than bogs. Because of this, they support a more diverse plant community including grasses, sedges, reeds, and wildflowers. Like bogs, fens are found only in the northern hemisphere and have low temperatures, a short growing season, and high levels of precipitation and humidity.
Wetlands are among the most productive ecosystems in the world.
In terms of biodiversity , they are comparable to rain forests and coral reefs. This material forms a solid base for a large food chain. It feeds shellfish and small insects and fish which are food for many larger animals. In addition to providing habitat for many and varied species, wetlands are extremely important to people and to the environment generally. Wetlands plants old soil in place with their roots, absorb the energy of waves, break up the flow of river and stream currents, and slow water speeds generally.