Soil development along an elevational transect on the western slopes o
f the central Sierra Nevada was investigated to assess the effects of
climate on soil properties and processes, The transect of seven soils
formed in granitic residuum spans elevations from 198 to 2865 m with m
ean annual temperature and precipitation differences of 13 degrees C (
3.9-16.7) and 94 cm (33-127), respectively. Soil pH decreased by about
two units and base saturation decreased from 90 to 10% with increasin
g elevation. Concentrations of organic C in the solum increased with e
levation, with the largest single increase occurring between the oak w
oodland (5-6 kg C/m(2)) and mixed-conifer sites (10-15 kg C/m(2)). Cla
y mineralogy showed a general trend of desilication and hydroxy-Al int
erlayering of 2:1 layer silicates with increasing elevation, The degre
e of chemical weathering, based on clay and secondary Fe oxide concent
rations in the solum, showed a maximum (clay = 536 kg/m(2) and Fe oxid
es = 24 kg/m(2)) at mid-elevations having intermediate levels of preci
pitation and temperature. While some soil properties show a continuous
progression (e.g., organic carbon, base saturation, clay mineralogy)
with elevation, other properties (e.g., pH, soil color, clay and secon
dary Fe oxide concentrations) show a pronounced change (threshold-type
step) over a short distance at about 1600 m. The explanation for the
abrupt nature of this shift is not known; however, it coincides with t
he approximate elevation of the present-day average effective winter s
now-line. (C) 1997 Elsevier Science B.V.