HISTORY OF THE FOREST OF CENTRAL TIERRA DEL FUEGO, ARGENTINA

Abstract

Nothofagus pumilio is the most important native forest species in Tierra del Fuego; it covers an area of 214,000 ha and is the main source of wood. In this work a contribution is made with the elements for the reconstruction of the history of the Nothofagus pumilio deciduous forest in the centre of Isla Grande de Tierra del Fuego, at the southeastern end of the American continent. The reconstruction was performed by means of pollen analysis out of a peat bog profile located in the Argentine sector of Isla Grande de Tierra del Fuego. Pollen grains were extracted by physical and chemical techniques; they were determined and counted, and per centual data were statistically treated through ordination analysis (CA programme). Changes in pollen content along the profile show variation of the environmental parameters during the Holocene with relation to the transition from steppe to forest. We demonstrate that in the centre of the isle, between ca 6,800 and 7,775±205 years BP there was a gramineous steppe, later an open forest between 2,340±35 and 2,755±45 years BP, and as from 1,725±35 years BP a closed forest started developing up to now. These changes are related to the increasing precipitation. The asynchrony in the establishment of forests in other sites of Tierra del Fuego is due to humidity gradients of the southern winds.