Bill Sexton
ABSTRACT
| Soil-parent material relationships were studied for common parent material types on the Clearwater and Nezperce National Forests in northern Idaho. Parent material types are used as a primary stratification of forested, mountainous landscapes to define units for land management of relatively homogeneous capabilities and limitations. Parent material types included in the study were: basalt, granite, gneiss, schist, quartzite, siltite, volcanic ash and a local form of metamorphosed andesite (Seven-Devils formation). Major soil properties were described for 89 representative profiles on an "average per inch" basis for soil properties. Particle size distribution for percentage sand, silt, clay and coarse fragments, CEC, percentage base saturation, pH, profile characteristics and soil development trends were evaluated. Significant differences were found between some soil properties in all cases. The number of soil properties found to be different and the degree of separation varied by parent material. Properties of surface volcanic ash layers were found to differ significantly between the western red cedar and grand fir zones. No differences were found within residual parent material classes between vegetative zones. Paleosols previously believed limited to grassland and forest transition areas were found to occur under forest sites. Andeptic Paleboralfs were found on all residual parent material types studied but were common only on siltite and basalt. Parent material types were found to provide a useful inference base for predicting major soil properties for related forest land management planning. |