Soil organic carbon stocks in the high mountain permafrost zone of the semi-arid Central Andes (Cordillera Frontal, Argentina)

This study presents the first detailed soil organic carbon (SOC) inventory for a high mountain permafrost zone in the semi-arid Central Andes of South America. We describe plant cover and soil profiles at 31 sites representing the main land cover and landform types in the Veguitas catchment (Cordillera Frontal, Argentina), which ranges in elevation from c. 3000 to 5500 m. The vegetated area with soil development is largely confined to altitudes 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 kg C m−2, which is reduced to 0.33 kg C m−2 if we consider negligible SOC stocks in the extensive bare ground and glaciated areas at higher elevations. Hotspots of SOC storage are wet meadow areas, with peat deposits up to 102 cm deep and a maximum 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 contribution to mean SOC storage is limited. Among soils at well-drained sites, highest mean SOC 0–100 cm storage is found on backslope positions of moraines that predate the Last Glacial Maximum (6.87 kg C m−2). Only 2% of all SOC stocks in the catchment are found in permafrost terrain and none are located in the permafrost layer itself. The main ecoclimatic control on SOC storage is plant cover, with vegetation limits being sensitive to ambient temperature. Projected increases in temperatures will not remobilize any frozen SOC stocks but will likely result in an upward shift of the upper vegetation belt with soil development creating new areas of phytomass carbon and SOC storage. The area is expected to represent a net C sink and thus a negative feedback on future global warming.Fil: Kuhry, Peter. Stockholms Universitet; SueciaFil: Makopoulou, Eirini. Stockholms Universitet; SueciaFil: Pascual Descarrega, Didac. Stockholms Universitet; SueciaFil: Pecker Marcosig, Ivanna. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Trombotto, Dario Tomas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentin

Periglacial and glacial landform mapping in the Las Veguitas catchment, Cordillera Frondal of the Andes (Argentina).

The semi-arid and arid Andes of South America are characterized by large areas with glacial and periglacial environments. This study focusses on the distribution of glacial and periglacial landforms in the Las Veguitas catchment, Cordillera Frontal, Argentina. A detailed geomorphological map of the Las Veguitas catchment is presented, based on high-resolution elevation data (ALOSPALSAR), satellite imagery (Landsat 8, World View 2, Google Earth), and field studies. First, a general topographical analysis is performed for the entire Las Veguitas catchment, including elevation, slope and aspect characteristics. Second, the altitudinal range of glacial features (glaciers, debris covered glaciers and thermokarst ponds on glaciers) and the altitudinal range and predominant aspect of periglacial features (active, inactive and fossil rock glaciers) are analyzed. Currently, glaciers are restricted to ≥ 4300m, but moraines are identified to elevations of c. 3200m. Active rock glaciers extend down to c. 3450m and have a more southern aspect then both inactive and fossil rock glaciers. Third, a temporal analysis has been performed of glacier and rock glacier flow using a time series of remote sensing images. Glacier flow traced by the displacement of thermokarst lake features (2006-2016) had a mean velocity of 6.66m/yr. The mean velocity of rock glaciers (1963-2017) was much lower at 0.63m/yr. Finally, the thesis discusses limitations and uncertainties in study methods and suggestions for further research activities