Late Pleistocene and Holocene palaeoenvironmental changes in central Tierra del Fuego (similar to 54 degrees S) inferred from pollen analysis

摘要

A pollen record was obtained from a coring site at La Correntina mire (54 degrees 330S, 66 degrees 59'W, 206 ma.s.l.) to the east of Lago Fagnano, centre of Tierra del Fuego. The results indicate that the valley bottom was free of ice shortly before 15,400 cal BP. Pioneer vegetation included dwarf shrub heaths, grasses and herbs with sparsely distributed Nothofagus trees, indicative of dry conditions. Nothofagus expanded by 10,000 cal BP and the forest-steppe ecotone was established by 9,400 cal BP, implying warm conditions and an increase in available moisture. After ca. 5,000 cal BP, the development of a closed-canopy forest is interpreted as the result of wetter and colder conditions. After 3,000 cal BP, Nothofagus forest became more open, and by about 400 cal BP there was a further decline of the forest. A closed-canopy Nothofagus forest re-established after 400 cal BP.