Carbon accrual in the Atacama Desert

The Atacama Desert is the oldest and driest desert on Earth, nevertheless traces of life have been observed in several places, accumulating residues of organic matter (OM) in the desert soil. We evaluated to which degree the distribution of soil organic carbon (SOC) stocks depends on aridity. We questioned that these OM traces of life preferentially accumulate in topsoil and investigated whether there was also an enrichment of OM in deeper subsoil. We sampled four west-east directed transects with increasing distance to the coast, spanning the Atacama Desert from north to south, plus a hyperarid site at Yungay in the centre of the desert. With a nested sampling design we addressed topsoil heterogeneity at each sampling site (n ≤ 18). For 12 of these sites soil profiles were dug to 0.6–2.0 m depth. The SOC concentrations were determined for each sample by temperature-dependent differentiation of total carbon