Abstract

Soils under coigüe de Magallanes (Nothofagus betuloides (Mirb) Blume) forests, located in the oriental part of Tierra del Fuego (54°45?-54°15? S, 68°40?-70°10? W), were characterized morphologically, physically and chemically. Associated tree species were lenga (Nothofagus pumilio (P. et E.) Krasser) and canelo (Drimys winterii Forst.). A total of 85 soil profiles and approximately 250 soil cores were described. The soils in the N. betuloides forests were young, heavily influenced by the volcanic activity, topography and climate. The presence of the orders Spodosol and Iceptisol was recorded. Soils range from thin to very thin, with a high skeleton volume, loamy texture, structure ranging from massive to granular, with a low water retention capacity, and a moderate to slow drainage. They present high acidity (pH 4-4.5), low nutrient concentration and high levels of aluminum. The litter layer (Oe/Oa) presents adequate root development. There was generally a white horizon (frequently 10 YR 5/1-2) immediately below the litter, with a loamy texture, massive structure, and low rooting levels. The origin of this horizon is hypothesized to be related with pedogenic factors on volcanic ash deposits. It is concluded that the fertility of forest soils is low, mainly due to physical and chemical characteristics.