Great Basin Naturalist


The Pine Butte Fen, situated east of the Rocky Mountains in north central Montana, is a boreal, patterned peatland occurring in a relatively dry climatic region. It is one of the southernmost mires of its kind in North America. The vegetation communities present in the fen are described, and possible causes of vegetation patterning are discussed. The Pine Butte Fen is a minerotrophic fen with 93 species of vascular plants represented in an area of approximately 450 ha. Floristic similarities between the Pine Butte Fen and 11 other peatlands in North America reported in the literature are low. Similarity of this fen to other peatlands tends to decrease with increasing distance between the sites and decreasing pH of surface water at other sites. Possible causes for these trends and the floristic uniqueness of the Pine Butte Fen are discussed.