Groundwater defined: water within the earth that supplies wells and springs
The National Forest system contains substantial groundwater resources. Millions of Americans drink and use groundwater each day. The availability and quality of groundwater depends primarily on geologic conditions--where the water is located underground; the rate it flows; and the quality of the water, which is influenced by the filtering capacity of the rocks.
Groundwater makes up 1.7% of the world's total water. Approximately 30% of the world's fresh water supply of the water used annually comes from underground sources. It is a valuable commodity and its use is growing nationwide. National Forests and Grasslands overlie important aquifers and also serve as recharge areas for thousands of rural water supplies.
Groundwater Dependent Ecosystems
Groundwater-Dependent Ecosystems are ecosystems that must have access to groundwater to maintain their ecological structure and function. They are a diverse, complex and often biodiverse subset of the world's ecosystems. They can be located in marine, coastal, riparian, in-stream, terrestrial, cave and aquifer environments.
Fens--Where Groundwater and Ecology Meet
Fens are important ecosystems in the National Forests. Many ecosystems have evolved under conditions where groundwater is critical to the survival of special groups of species. Fens are a type of wetland that is groundwater-fed. This produces their unique ecological characteristics. Fens can occur anywhere there is enough groundwater to saturate the soil throughout the year. Fens are numerous in most mountainous regions of the United States. They are found in most National Forests.
Plant community types can be unique to fens. Many fen plants are similar throughout North America, while others are more localized; such as the swamp pink found in southern and central Appalachian fens.
Fens take thousand of years to form. In glaciated areas of the western U.S., fens began forming as soon as the ice melted, 9,000 to 11,000 years ago