Holocene vegetation dynamics and human–environment interactions inferred from pollen and plant macrofossils from caves in northwestern Patagonia (Argentina)

Abstract

The present contribution describes the Holocene vegetation, climate, and plant–human interactions in northwestern Extra-Andean Patagonia, Argentina. Pollen and plant macrofossil records from sediments of two archeological caves located at 40° S in the shrub-grass steppe provide new information on the Holocene history of vegetation and the relationships between human occupations and paleoenvironmental conditions of this semi-arid region. Our results suggest that the Early Holocene (ca. 11,400–8500 cal. BP) grass steppe developed as a result of colder and moisture conditions than today. During the Mid-Holocene (ca. 8500–5800 cal. BP), a progressive increase in temperature and dry conditions allowed an increase in shrub communities. After ca. 5800 cal. BP, winter precipitation and summer dryness and a more accentuated climate variability between ca. 2500 and 1600 cal. BP promoted an increase in shrubs over grasses and the establishment of a shrub-grass steppe similar to the present one. These paleoclimatic patterns show some disagreement with other paleoenvironmental records from northwestern Patagonia, particularly with those from the Early and Late Holocene. Collection of plant resources by hunter-gatherer groups began at ca. 8000 cal. BP and intensified and diversified after ca. 5800 cal. BP, along with the relatively intense human occupations of caves. This can be linked to the climatic conditions being similar to the present ones and to the greater availability of woody plants for fuel and other different uses, which had implications for human subsistence and adaptation to the drylands and their resources.