What defines a fen wetland?
A fen is a peat-forming wetland supplied by groundwater or mineral-rich surface water in addition to precipitation. Water moving through soil and rock carries dissolved calcium, magnesium, bicarbonate, and other ions, making most fens less acidic and more nutrient-rich than rain-fed bogs. Some are neutral or alkaline, especially in limestone regions, although mildly acidic fens also occur; groundwater influence is more fundamental than a universally high pH. Sedges, grasses, brown mosses, and specialized flowering plants commonly dominate, and peat accumulates because saturation restricts oxyg
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 2-3
