Pollen and fungal remains as environmental indicators in surface sediments of Isla Grande de Tierra del Fuego, southernmost Patagonia

MUSOTTO LORENA; BIANCHINOTTI MARÍA VIRGINIA; BORROMEI ANA

PALYNOLOGY

AMER ASSOC STRATIGRAPHIC PALYNOLOGISTS FOUNDATION

Año: 2012 vol. 36 p. 162 - 179

0191-6122

Palynological studies (pollen and fungal remains) have been performed in order to increase the knowledge of present vegetation and fungal biota. The analysis of modern analogues will help to improve the palaeoenvironmental reconstructions of fossil sequences from Isla Grande de Tierra del Fuego. A total of 30 fungal remains have been found, described and illustrated for further reference. Surface samples were collected from the different vegetation communities developed in the island: steppe, Nothofagus forest-steppe ecotone and Nothofagus forest. The steppe is characterized by predominance of Poaceae pollen aPalynological studies (pollen and fungal remains) have been performed in order to increase the knowledge of present vegetation and fungal biota. The analysis of modern analogues will help to improve the palaeoenvironmental reconstructions of fossil sequences from Isla Grande de Tierra del Fuego. A total of 30 fungal remains have been found, described and illustrated for further reference. Surface samples were collected from the different vegetation communities developed in the island: steppe, Nothofagus forest-steppe ecotone and Nothofagus forest. The steppe is characterized by predominance of Poaceae pollen accompanied by Nothofagus pollen (up to 30%) and spores of Glomus sp. The forest-steppe ecotone displays increases in Nothofagus pollen frequency (up to 50 %) along with dwarf shrub heath communities and records of Gaeumannomyces species. In the forest unit the percentage values of Nothofagus pollen surpass 50%. Among the fungal remains, fructifications of Microthyriaceae and dematiaceous spores such as Alternaria sp., Dictyosporium sp. and Sporidesmium sp. are present in forest samples and may be probably related to damp environments. Ascospores of the coprophilous Sordaria-type and Sporormiella sp. appeared to be of common occurrence and are probably associated with livestock grazing. Fungal remains are very scarce in some of the samples obtained in mire environments. The ecological requirements of some of the fungi identified allowed inferences about local conditions of sampled site. This study showed the palaeoenvironmental indicator value of fungal components and encourages further investigation of surface samples considering local habitat features to arrive at sharper indication.