Soil Organic Carbon Content in Frigid Southern Appalachian Mountain Soils

Abstract

Limited information is available on soil organic C (SOC) sequestered in frigid soils of the southern Appalachians, although the soils in frigid areas probably hold more SOC than warmer soils in the region. This study determined SOC in high‐elevation (>1300 m) soils across northeast (N) and southwest (S) aspects and across three slope classes (7–15, 15–35, and 35–55%) per aspect in the Ridge and Valley of southwest Virginia. Overall, rock fragment content and bulk densities were lower, B‐horizon SOC was higher, and sola were shallower than reported in similar regional studies. The A horizons were thicker on N versus S aspects, as were the sola (57 vs. 47 cm). Sola were 50% thicker on N35 to N55% sites than on S35 to S55% sites (65 vs. 44 cm). The S35 to S55% sites had the thickest litter but the thinnest A horizons, and were characterized by the highest C/N ratio and least incorporation of leaf litter. The study area average mass SOC was 112 Mg ha−1 More mass SOC was retained on S than N aspects in litter layers but less was retained in the A horizons and whole solum (99 vs. 127 Mg ha−1). There was less solum mass SOC on S7 to S15% and S35 to S55% sites than on N15 to N35% or N35 to N55% sites. The results reinforce the importance of using mass SOC rather than SOC concentration in regional SOC studies and demonstrate that steep northeast‐facing slopes in frigid Appalachian landscapes have the highest mass SOC and highest potential for sequestering organic C in the soil.