Pedogenesis and Soil-Geomorphic Relationships in an Arid Mountain Range, Mojave Desert, California

摘要

Mountains are impressive features of many desert landscapes because of their elevation, complex topography, and sheer extent. Soil genesis and landscape processes were studied in the southern Fry Mountains, Mojave Desert, California. Our aim was to better understand the processes responsible for the distribution of soil properties in this landscape. Measured properties in 65 soil pits across the study site show that dust, soluble salt, NO3--N, and carbonate distributions are correlated with the prevailing wind direction. This finding suggests that the mountain range effectively traps eolian sediment. Soils mantling these mountains have accumulated, on average, 41 kg m(-2) silicate dust, 172 g m(-2) soluble salts, 3.3 g m(-2) NO3--N, and 79 kg m(-2) carbonate and reached maximum concentrations of 156 kg m(-2), 1800 g m(-2), 43 g m(-2), and 398 kg m(-2), respectively, on windward sides of the range. The basin floor encompassing Soggy Lake, an upwind playa, is the probable primary source of these materials. Soil morphology and land surface characteristics from four major mountain landforms were used to interpret the pedogenic and soil-geomorphic processes that have led to the distribution patterns of these accumulations. Our study demonstrates that arid mountains accumulate and store appreciable quantities of dust, soluble salts, NO3-, and carbonate and are therefore important to the overall geomorphic evolution and biogeochemical cycling of the region. The previously unaccounted storage of pedogenic carbonate in similar mountain ranges could increase the global soil inorganic C pool estimate by as much as 15 to 174 Pg C.