Sphagnum fuscum hummocks. Known occurrence of "Sphagnum fuscus" are on the map above. The moss inhabits boreal forests and marshlands primarily, and is more likely to be found in colder climates. The moss is also capable of inhabiting areas of relatively high elevation. In recent studies performed in Eastern Europe, it was found that stable carbon and oxygen isotope ratios in α-cellulose of "Sphagnum fuscum" stems subsampled from hummocks and peat plateau profiles are useful indicators for summer temperature and winter precipitation at decadal to millennial timescales. In another study conducted in Alberta, Canada, it was found that "S. fuscum" serves as
Sphagnum fuscum Endangered species lists within some German states. Switzerland has labelled "S. fuscum" as vulnerable. In the United States, "S. fuscum" is reported to be at risk in the state of North Carolina. Across Europe, "S. fuscum’s" habitats are under protection. Germany and Switzerland have both placed the moss under “special protection.” This species is associated with "Sphagnum angustifolium", "S. fallax", "S. magellanicum", "S. papillosum", more infrequently with "S. teres", and "S. warnstorfii" in richer sites. "Sphagnum fuscum" is easily discernible from other species of Sphagnum, as it tends to be reddish brown in color, and is more likely to form