Soil evolution along an altitudinal transect in the Eastern Mojave Desert of Nevada, U.S.A.

Abstract

Six soil profiles were examined along an altitudinal transect, from 840 to 2170 m, in the eastern Mojave Desert of southern Nevada. The soils formed on gravelly limestone alluvium which varied in age from Holocene to mid-Pleistocene. Climate and vegetation varied from an arid, desert scrub community at the low elevation to a sub-humid, coniferous forest at the highest elevation. Silicate clay mineralogy was similar to that of the parent material in all the Holocene soils but differed with elevation in the mid-Pleistocene soils, these being dominated by palygorskite at 1400 m and smectite at 2150 m. Pedogenic carbonate content of the Bk horizons and morphologic stage of carbonate accumulation increased with soil age with the exception of the 2150 m site where excess moisture leaches carbonate out of the profile. DCB-extractable iron increased with both age and elevation whereas soil organic C and CO 2 increased primarily with elevation, reflecting the gradient in moisture regime and biologic productivity. Aeolian dust may have a strong role in the formation of the vesicular, platey surface horizons at many of the sites.