Mount Emmons Iron Fen
Location: Gunnison CountySize: 75 acresDesignated: June 1999Land Manager: US Forest Service
The Iron Fen is a wetland complex consisting of forested wetland, sedge fen, and a pond, all underlain by peat enriched with iron oxide (limonite). Although commonly referred to as a bog, the wetland is actually a fen. Bogs are wetlands which are disconnected from the water table and receive substantially all their moisture from rain and snow. Fens are fed primarily by ground water, and vary along a chemical gradient ranging from "rich" (enriched by mineral ions) to "poor" (poor in mineral ions). Rich fens usually have a high pH, poor fens a low pH. Mount Emmons and a very few other iron fens in the southern Rocky Mountains are the exception – they are rich in mineral ions (especially iron and sulfur) but have a very low pH. The wetland and its unusual ecology are the primary feature of the Natural Area.
The unusual chemistry results in an unusual flora, similar to that of nutrient-poor "true bogs". Sphagnum mosses and small orchids are common throughout forested and open parts of the Mount Emmons wetland, and the margins of the pond support one of only two populations of the roundleaf sundew (Drosera rotundifolia) known from Colorado. Two unusual species of dragonfly (Leucorhinea hudsonica and Sematochlora semicircularis) frequent the wetland.