Insights into Holocene vegetation and climate changes at the Southeast of the Andes: Nothofagus forest and Patagonian steppe fire records

SOTTILE, GONZALO; BAMONTE, F.; MANCINI, M. V.; BIANCHI, M. M.

HOLOCENE (SEVENOAKS)

SAGE PUBLICATIONS LTD

Año: 2012 vol. 22 p. 1309 - 1322

0959-6836

Ecosystem fire regimes are a consequence of interactions among fuels and climate. The reconstruction of past fire regimes are of great importance for studying past climate changes and controls. The aim of this study is to compare two charcoal and pollen records from the Nothofagus forest-grass steppe ecotone (50ºS) and the grass steppe (49º). We compare fire regimes responses to local vegetation changes, and inferred variation on climate conditions between 49º and 52ºS during the Holocene. Cerro Frías and La Tercera charcoal records seem to be sensitive to centennial and millennial time scales vegetation and climate variability inferred for southern Patagonia. During Pleistocene- Holocene transition and during the middle Holocene, forest patchiness provided fuel vertical and horizontal continuity favoring fire activity. In contrast, in steppe environments high cover of shrubs favored grass patchiness impeding fire spread. Higher pollen richness and variability through time seem to be related to higher vegetation patchiness. Past fire regime variability at the eastern side of the Andes has been closely related to westerly moisture influence between 52º and 48º S. Southern latitudes have been influenced by polar air masses intrusions to the continent during the last 5000 cal yr BP.