SPODOSOL DEVELOPMENT AS AFFECTED BY GEOMORPHIC ASPECT, BARAGA COUNTY,MICHIGAN

In midlatitude locations with steep slopes, geomorphic aspect can be a n important factor in determining spatial variations in soil developme nt This study examines the influence of aspect on soil development in Baraga County, Michigan, as a means of explaining within-landform vari ability. The soils are sandy and have spodic morphologies. All are loc ated on steep slopes (45-73%) of contrasting aspect. Ten pedons each f rom backslopes on north-to northeast (N-NE) and south-to-southwest-(S- SW) facing slopes were described, sampled, and compared using standard techniques. Variation in slope gradient was not, statistically, a det ermining factor in the differential soil development found here. Aspec t has strongly influenced soil development, however, with soils more s trongly developed (i.e., more podzolized) on N-NE slopes than on S-SW slopes. Several soil characteristics indicative of strong podzolizatio n were found on N-NE slopes, including higher values of solum thicknes s and POD index, greater losses of extractable Fe and Al from E horizo ns and concomitant gains in B horizons, and darker and redder E horizo n colors. Soils were generally cooler on N-NE slopes in summer, with e ssentially similar temperatures under snowpacks in winter. Cooler temp eratures and greater amounts of infiltrating water in soils with N-NE aspects may have accelerated podzolization by allowing more organo-met allic complexes to be formed and translocated. Podzolization driven by translocation of amorphous, inorganic compounds appears, however, to be nearly equivalent on sites of differing aspect. Of the ten pedons o n N-NE slopes, nine classified as Spodosols (Entic or Typic Haplorthod s) and the other was an Entisol. Seven of the 10 pedons on S-SW slopes classified as Entisols (Udipsamments or Udorthents), and the remainin g three were Spodosols.