Extent of available data.
This data layer depicts the locations of Calcareous fens. It was developed by the Minnesota Department of Natural Resources. Calcareous fens are a unique type of wetland. They have a substrate of non-acidic peat and require a steady supply of oxygen-poor groundwater that is rich in calcium and magnesium bicarbonate. They are among the rarest natural communities in the United States and support multiple rare plant species. They are especially vulnerable to surface and sub-surface disturbances that affect their groundwater regime.