Alpine Soils on Mount Mansfield, Vermont, USA: Pedology, History, and Intraregional Comparison

摘要

The highest summits in the northeastern United States rise above the tree line and support unique islands of alpine tundra. Little is known about the properties and history of these soils and it is unclear how soils compare between the separate, isolated alpine areas. As a step toward addressing this oversight, the physical and chemical properties of alpine soils were investigated on Mt. Mansfield, the highest mountain in Vermont. Soil thickness was determined through probing, while profile development and horizon properties were investigated in 31 excavations. Soil covers 85% of the study area, with profiles averaging 18 cm thick (maximum of 58 cm). Most profiles demonstrate a variation on the sequence Oi, Oa and/or A, Bw or Bs (rare), AC, and Cr horizons. The Oa horizons contain significantly more C, Ca, K, and Mg than A horizons, and have higher cation exchange capacity and base saturation, and lower pH values. Almost one-third of the profiles were classified as Histosols, while nearly twice as many were classified as Entisols. Only two profiles contained cambic horizons and were classified as Inceptisols. Histosols contained significantly more K and organic matter than Entisols. A buried Sphagnum layer, radiocarbon dated to approximately 1000 yr ago, suggests a wetter climate at that time. Mount Mansfield soils are generally thinner than those described from nearby alpine environments and contain more organic matter with higher C/N ratios. Intraregional comparison suggests that carefully selected soil profiles could be combined to form litho-, climo-, and biosequences to elucidate controls on soil formation in these environments.