Mountain fens are uncommon and unique wetlands in the southern Appalachian
Highlands. We selected four mountain fens in North Carolina to compare soil
particle-size distribution, organic carbon, pH, cation exchange capacity (
CEC), and exchangeable Mg+2, Ca+2, and K+. Three of the sites are depressio
nal areas on alluvial floodplains at elevations between 700 and 1130 m abov
e sea level, while the fourth site is located on a slope intersecting groun
d-water seepage at an elevation of 950 m. Feat accumulation amounted to a s
hallow surface Sphagnum layer (usually <5 cm) at three sites, and the organ
ic carbon content of the surface soil horizon ranged from 4 to 21%. Three o
f the soils would be classified as Cumulic Humaquepts, and the other is a T
erric Haplohemist. The pH of the surface horizon of the four soils ranged f
rom 4.3 to 4.9. The alluvial fens had higher silt concentrations than the s
eepage fen, and two of the alluvial fens had a subsurface, fine-textured de
posit. The seepage fen showed little textural variation with depth. Exchang
eable Ca+2 concentrations were higher for the seepage fen. The CEC ranged f
rom 15 to 62 cmol, kg(-1) in the surface horizon, and base saturation (Ca+2
, Mg+2, and K+) was <12% for the three alluvial fens and 20% for the seepag
e fen. Base saturation increased to 40% in the lower horizons of the seepag
e fen but remained <10% for the alluvial fens. The differences in soil char
acteristics suggest that geomorphic location should be considered when comp
aring mountain fens.