Possible prehistoric anthropogenic effect on Araucaria angustifolia (Bert.) O. Kuntze expansion during the late Holocene

Abstract

This study offers a few thoughts about a possible prehistoric anthropogenic effect on the expansion of Araucaria angustifolia during the late Holocene based on overlay and analysis of archeological, geographical, palynological and botanical data. Archeological research reveals that groups of pottery-producing hunter-gatherers belonging to the Jê linguistic stock. These are archeologically defined as the Taquara/Itararé Tradition, and occupied the highlands in southern Brazil from 2000 years BP until 200 years BP. Major resource uses regarding forest vegetation were hunting, Araucaria nuts seed harvesting (considered an essential component in the diet) and agroforestry management. Their settlements, known as casas subterrâneas (pit houses), were distributed according to relief and geography under the domain of Araucaria forest. A strong expansion of Araucaria angustifolia in the late Holocene is recorded by various palynological studies as occurring after 1,500 years BP in Paraná, 1,000 years BP in Santa Catarina and 1,140 years BP in Rio Grande do Sul over areas near archaeological settlements. These data deserve some attention. Furthermore, botanical sources indicate that Araucaria angustifolia need a dispersing factor, including birds, animals and humans. In spite of climate conditions being considered one of the major causes of increase, the possibility of contribution by pottery-producing hunter-gatherers of the Taquara/Itararé Tradition in seed dispersal by harvesting of seeds, and possible management and planting of this species. These sites are considered important elements as indicators of Araucaria forest areas in landscape reconstruction studies.