Water and soil chemistry, floristics, and phytosociology of the extreme rich High Creek fen, in South Park, Colorado, U.S.A.

Abstract

An extreme rich fen complex located in South Park, Colorado, is the most southern representative of this ecosystem type known in North America and the first described from the Southern Rocky Mountains. The fen is fed by ground water emerging from glacial outwash and has pH ranging from 7.6 to 8.3 and Ca2+ concentrations greater than 50 mg kg−1. The very low precipitation–evapotranspiration ratio in South Park causes Na+ and Mg2+ salts to accumulate in some soils, forming sodic peats that support halophyte communities. Character species of this fen include Kobresia simpliciuscula, Trichophorum pumilum, Carex scirpoidea, Carex microglochin, Carex livida, Utricularia ochroleuca, Triglochin palustris, Triglochin maritima, Salix Candida, Salix myrtillifolia, Salix serissima, Thalictrum alpinum, and Scorpidium scorpioides. A hierarchical classification of the vegetation is developed using numerical and table methods and includes 14 aquatic, peatland expanse, and salt flat communities. The most floristically similar fens occur in northern Ontario, northwestern Wyoming, and northern Montana. Keywords: peatland, extreme rich fen, South Park, Colorado, Rocky Mountains.