Rich Fen Bryophytes in Missouri: Ecological Comments and Three State Records

Aneura pinguis (L.) Dum., Calliergonella cuspidata (Hedw.) Loeske, and Campylium stellatum (Hedw.) C. Jens. are reported new to Missouri from calcareousfens of the eastern Ozarks. Aneura occurs farther south in Arkansas and Oklahoma, but the Calliergonella and Campylium are disjunct and at the southernmost known limits of their ranges in the Midwest. It is probable that these fens in Missouri provide relict habitats for species that were more widespread in the lower Midwest during Pleistocene full glacial time. Calliergonella is documented from Alberta, Canada as well. Fens are grass-, sedge-, or reed-dominated, peat- forming ecosystems that develop under the influ- ence of mineral-rich ground water (Crum 1988). Like bogs, fens are systems in which productivity exceeds decomposition and hence peat, rich in or- ganic material, accumulates. Fen peat forms a sub- strate upon which unique assemblages of plants are found. These include a diversity ofbryophytes, from peat mosses of the genus Sphagnum that dominate in acidic poor fens to "brown" mosses, mostly of the families Amblystegiaceae and Brachytheciaceae, that dominate in alkaline, rich fens. Fens are most abundant in boreal landscapes that, in North Amer- ica, have been recently glaciated. As temperatures increase, decomposition rates increase (Damman 1979); therefore, farther south in temperate North America fens decrease in abundance. In the central Midwest, they form a minor component of the land- scape. Missouri fens are calcareous communities that occur mainly in the unglaciated Salem Plateau re- gion in the Ozarks of southeastern Missouri (Kurz