High-Elevation Forest Soils of the Southern Appalachians: I. Distribution of Parent Materials and Soil-Landscape Relationships

Because of geomorphic instability imparted both by present-day slope processes and past periglacial activity, soils in the high-elevation spruce-fir (Picea rubens Sarg.-Abies fraseri [Pursh.] Poir) zone of the southern Appalachians have similar morphological features that make it difficult to assess their variability on the landscape, despite widespread differences in parent material and local geology. We used multiple discriminant analysis to (i) determine whether soils from three extensive areas of southern Appalachian spruce-fir forests could be separated by physical, morphological, chemical, and mineralogical properties, (ii) determine the relative effectiveness of these properties as differentiae, and (iii) assess the contribution of mineral weathering in offsetting potential base-cation depletion induced by strong-acid anion loading associated with atmospheric deposition. A total of 35 pedons at elevations >1450 m were characterized on the high mountain peaks of eastern Tennessee, western North Carolina, and southwestern Virginia. Physical and morphological properties used to separate and field classify these soils were not significantly different between study areas. Soil chemical and mineralogical properties inherited from different parent materials, however, were sufficiently different between study areas to result in the clear separation of soils into distinct groups with >95% classification accuracy. Soils formed from siliceous metavolcanic parent materials were dominated by K-feldspar and quartz in both the sand and silt fractions. Soils with parent materials derived from more high-grade metamorphic rocks were less quartzitic, had plagioclase as the dominant feldspar, and had high contents of expansible 2:1 phyllosilicates. Slope processes involved in the transport of solutes and sediments resulted in sorting of surficial materials, higher pH, and greater amounts of silt-size mica and kaolinite in depositional areas.