High-elevation spruce-fir forests in the southern Appalachians may potentially be in a state of decline as a result of either natural or anthropogenic causes. Soils were investigated in areas representative of 117 permanent intensive field plots established to evaluate changes in forest composition that may be influenced by the deposition of atmospheric pollutants. A total of 35 pedons were described, sampled, and characterized. Over 75% of the soils studied were classified in the field as either Typic or Pachic Haplumbrepts, but weakly developed spodic horizons were identified in 13 of the soils by chemical determinations in the laboratory. A high degree of morphological similarity exists between soils in these areas despite widespread differences in parent material and local geology. This similarity is the result of physical mixing of these soils by climatically-driven slope processes. A considerable amount of chemical variability exists in these soils which is not expressed in morphological characteristics. Multiple discriminant analysis established that physical and morphological properties used to separate and classify these soils in the field were not significantly different between study areas. Parent material differences, however, expressed in both soil chemical and mineralogical properties, were sufficiently different between study areas to result in the clear separation of soils into distinct groups. The importance of nutrient cycling in these spruce-fir forests is underscored by high levels of exchangeable bases in surface horizons relative to lower in the profile. This suggests that disturbances to the forest floor resulting from fire, overgrazing, logging, or erosion could have a major impact on ecosystem resilience during stress. / Master of Science

A forest site quality index (FSQI) based on topographic parameters of aspect, slope inclination and slope position was used to investigate soil moisture and plant water stress relationships on the southeast face of Potts mountain in Craig County, Virginia. Topographical effects on available water are especially pronounced during low late season rainfall levels encountered in the Ridge and Valley physiographic province of Virginia. The soil moisture trends and plant water potentials demonstrated that for all forest site quality index values representing the topographically derived moisture gradient, available soil moisture and plant stress levels probably seriously decrease or inhibit tree growth from the middle of July to the end of the growing season. The Forest Site Quality Index (FSQI) delineated the soil moisture gradient within the study area most successfully in the more xeric areas, supporting its use for predicting relative site quality on those sites where soil moisture has been demonstrated as being the limiting factor of tree growth. The FSQI is a rapid and easy measure based on topographic parameters for evaluating relative site quality but is restricted in use to areas where rainfall is critical to plant growth during the growing season. / M.S.