Soil Organic Carbon Variability by Aspect and Slope in the High Elevation Soils of the Southwest Virginia Mountains

by Miller, Jarrod O

Limited information is available on carbon(C)sequestered in frigid Appalachian forest soils. However,the cool moist forests of the high elevations probably hold more C than any other mineral soils in Virginia. The objectives of the study were to determine the amount and variability of soil C across aspect and slope classes in a frigid temperature regime area of Tazewell County, VA. Soils were sampled to characterize two aspect classes, N(340-90º) and S (160-270º), and three slope classes, 7-15%, 15-35%, 35-55%. Organic (L,F,H) and mineral layers and horizons (upper 5cm, A, B) were sampled at each site. Whole soil (including organic and mineral horizons) C contents on N aspects (135 Mg/ ha) were greater than on south aspects (107 Mg/ha). Average whole soil C across all sites was 112 Mg ha-1. The A horizons on N aspects (13cm) were deeper than those of the S aspects (8 cm), while average leaf litter weights were greater on the S aspects (25 Mg/ ha) versus the N (17 Mg/ ha). B horizon C was greater than 1.5 % and made up more than half of the total soil C. Carbon increased with slope on N aspects, but did not increase with slope on S aspects, because estimated solar insolation potential decreases with increasing slope on N aspects and has no trend on S-facing slopes. Total C appears to be greatest on steep N-facing slopes because cooler and moister conditions promote better mixing of organic material into the mineral soil.