ROCKY-MOUNTAIN FOREST SOILS - EVALUATING SPATIAL VARIABILITY USING CONVENTIONAL STATISTICS AND GEOSTATISTICS

Spatial variability of soils is a landscape attribute which soil scien tists must identify and understand if they are to construct useful soi ls maps. This paper describes the spatial variability of soils in a fo rested watershed in the Medicine Bow Mountains, Wyoming, using both co nventional statistics and geostatistics. principle Components Analysis indicated that flow accumulation and aspect were the two terrain attr ibutes that most economically described terrain variability. Thickness of A and B horizons, organic carbon and solum coarse fragments were v ariable in the study area (CVs of 40 to 58%). Simple correlation and r egression analyses suggested there were no statistically significant r elationships between soil properties (texture, pH, coarse fragments, o rganic carbon content) and terrain attributes (elevation, slope gradie nt, slope shape, flow accumulation, aspect). Geostatistical analysis i ndicated thickness and coarse fragment contents of the A and B horizon s, and solum thickness were spatially independent variables; however, pH, organic carbon content, and solum coarse fragment content were spa tially correlated. Spatial variability was described by both linear (p H and organic carbon content) and spherical (solum coarse fragment) mo dels. Use of geostatistics provided insight into the nature of variabi lity in soil properties across the landscape of the Libby Creek waters hed when conventional statistics (analysis of variance and regression analysis) did not.