Genesis of a Holocene soil chronosequence from the southernmost Andes Mountains, Tierra del Fuego

• Autor(a) principal: Schaefer, Carlos E. G. R.
• Data de Publicação: 2018
• Outros Autores: Sá, Mariana M. F., Bockheim, James G., Loureiro, Diego C., Michel, Roberto F. M., Simas, Felipe N. B.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: https://doi.org/10.1016/j.catena.2017.11.002; http://www.locus.ufv.br/handle/123456789/21981
• topic: Soil development; Soil classification; Podsolization; Andisolization; Cordillera Darwin; Soil chronosequence

At the southernmost Andes Mountains, the Martial cirque glacier has retreated 2 km in distance and 500 m in elevation since the mid-Holocene. This study examines soil properties, processes, and classification in relation to soil age and elevation. Soils were sampled at elevations from 430 to 925 m a.s.l. on drifts periodically influenced by volcanic ash that represent five age classes: 5.0 to 6.0 kyr BP under deciduous Nothofagus pumilio forest; 1.3 to 3.2 kyr BP under N. pumilio and N. antarctica forest and tundra; 0.3 to 1.4 kyr BP under tundra; 0.3 Kyr BP CE under tundra; and 0.007 Kyr BP CE under scattered lichens and mosses. The soils represent a developmental sequence on metapellitic rocks ranging from: Cryorthents, Dystrocryepts, Humicryepts, and Humicryods. In general the soils contain abundant coarse fragments, sandy loam textures, and high levels of organic C. Clays have been altered in the soils from chlorite to a hydroxyl-interlayered vermiculite and ferrihydrite. The most developed soils are very strongly acid, Al saturated, and have illuvial horizons enriched in fulvic-acid C and organic-bound forms of free Fe and Al. The following properties are highly correlated with soil age: pyrophosphate soluble iron (Fep) in the B horizon (R^2 = 0.97), color-development equivalence in the B horizon (R^2 = 0.87), clay content of the B horizon (R^2 = 0.68), and fulvic-acid C in the B horizon (R^2 = 0.65). The results of this study imply that soil formation in magellanic subantarctic forests and tundra is rapid and involves podsolization, andisolization, and humification as primary soil-forming processes.