CONICET | Buscador de Institutos y Recursos Humanos

This study presents the first detailed soilorganic carbon (SOC) inventory for a high-mountain permafrost zone in the semi-aridCentral Andes of South America. We describe plant cover and soil profiles at 31sites representing the main land cover and landform types in the Veguitascatchment (Cordillera Frontal, Argentina), which ranges in elevation from c.3000 to 5500 m. The vegetated area with soil development is largely confined toaltitudes of <3650 m and represents only 8.2% of the total catchment area.Mean SOC 0-100 cm storage for the vegetated portion of the catchment is 3.62 kgC m-2, which is reduced to 0.33 kg C m-2 if we consider negligible SOC stocksin the extensive bare ground and glaciated areas at higher elevations. Hotspotsof SOC storage are wet meadow areas, with peat deposits up to 102 cm deep and amaximum observed total SOC storage of 53.07 kg C m-2. These wet meadow areas,however, occupy only 0.11% of the total catchment area and their contributionto mean SOC storage is minimal. Among soils at well-drained sites, highest meanSOC 0-100 cm storage is found on backslope positions of moraines that predatethe Last Glacial Maximum (6.87 kg C m-2). Only 2% of all SOC stocks in thecatchment are found in mountain permafrost terrain and none are located in thepermafrost layer itself. The main ecoclimatic control on SOC storage is plantcover, with vegetation limits being sensitive to ambient temperature. Projectedincreases in temperatures will not remobilize any frozen SOC stocks but will resultin an upward shift of the upper vegetation belt with soil development creatingnew areas of phytomass carbon and SOC storage. The area is expected torepresent a net C sink and thus a negative feedback on future global warming

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