Fens are a special type of wetland - they are fed by groundwater, support vegetation that is very different from the plants on the surrounding uplands and some contain water that is alkaline (high pH values) or mineral rich. Fens are often dominated by rushes and sedges and they can support mosses, willows and even some trees.
|A fen complex in Pike/San Isabel National Forest. |
The fens are outlined in yellow, the NWI wetland is outlined in purple.
The fen complex pictured above contained a diverse array of plant species including water sedge (Carex aquatilis), peat moss (Sphagnum angustifolia), white water-crowfoot (Ranunculus aquatilis), diamondleaf willow (Salix planifolia), and resin birch (Betula glandulosa).
|Iron fens at Geneva Creek, note the terracing of the unvegetated surface.|
Iron fens are a special type of fen that occur on iron-rich substrates, and are unique to Colorado. The water that flows the iron-rich substrate is acidic and mineral rich, and forms limonite (iron saturated peat) which forms terraces and ledges. Note the small forested fen in the bottom left corner of the above photo: this forested iron fen is dominated by dwarfed Engelmann spruce (Picea engelmanni).