Pattern of glacial—interglacial vegetation in subtropical Chile

Abstract

Pleistocene vegetation in the Mediterranean climate region of subtropical Chile during >40,000 yr of the last glaciation stands in contrast with vegetation of the past 10,000 yr of the present interglaciation. During the last ice age, open woodland of southern beech (Nothofagus dombeyi and N. obliqua types) and Andean podocarp (Prumnopitys andina) mixed with grasses and composites, was established on unglaciated, low‐lying terrain now occupied by broad sclerophyllous plant communities. This marked vegetation change during a glacial‐interglacial cycle, inferred from pollen contained in a core from Laguna de Tagua Tagua (34°30'S), suggests a pattern applicable to the vegetational setting during repeated cycles throughout the Quaternary.

Ice‐age vegetation can be accounted for by year‐long domination of the polar maritime air mass at lower, middle latitudes, unlike modern interglacial type plant formations, which are regulated by seasonal interaction between subtropical and polar maritime air. Glacial‐interglacial shifting of air mass centers, as a cause for the changing distribution of species and plant communities, appears geared to events in the atmosphere/ocean system.

Key words:

• Quaternary pollen records
• plant migration
• paleoclimate