Late Holocene vegetal communities inferred from archaeological sites in the North-eastern Patagonia: anthrachological evidences from Zoko Andi 1 site (Argentina).

SÁNCHEZ J.O.; BREA M.; ZUCOL A.F.; MARTINEZ G.A. ; MARTINEZ G.A.

Uspallata

Conferencia; 4th Southern Deserts Conference; 2014

Laboratorio de ecología Humana

The principal aim of this poster is to present a preliminary floristic characterization of the environmental conditions which would have prevailed during the initial late Holocene in the lower basin of the Colorado River with anthracological data. This area is located in a semi-arid ecotonal landscape, crossed by an allochthonous river which flows into the Atlantic Ocean. Archaeological sites usually have scarce and very fragmentary anthrachological records, but the Zoko Andi 1 site has preserved an large amount of archaeological charcoal. This site presents two archaeological components related to distinct temporal periods from the Late Holocene. Charcoal assemblages were obtained from the lower component dated ~1500?1300 BP, which corresponds to the Initial Late Holocene. Radiocarbon data were obtained from both charcoal and bones. All charcoal fragments recorded are in stratigraphic position associated with cultural materials in a defined sector of the stratigraphy, units 5 and 6. Dispersed charcoal was employed to identify trees and/or shrubs found in the area around hunter-gatherer settlements. Charcoal is usually an indicator of human selection and use of forest resources. The archaeological charcoals were identified by examining freshly fracture surfaces in transversal, radial, and tangential sections using reflected light. They were identified using standard wood key, wood atlases, and descriptions by diverse authors and InsideWood Database (http://insidewood.lib.ncsu.edu/). The terminology for the wood features follows the IAWA Lists of Features Suitable for Harwood Identification. Charcoal remains were compared to extant species, particularly present-day taxa from south?central Argentina. The analysis of 94 samples of archaeological charcoal enabled the following species to be identified: Prosopis caldenia (36%), Prosopis flexuosa (2%), Senna aphylla (21%), Jodina rhombifolia (8%), Condalia microphyllia (20%) and Larrea divaricata (13%) related to Leguminoseae-Mimosoideae, Leguminoseae-Caesalpinioideae, Santalaceae, Rhamnaceae and Zygophyllaceae, respectively. First, Prosopis and Condalia (58%) are hardwoods and therefore have high caloric values and long combustible duration. They are an excellent source of heat and were probably used for heating, cooking and lighting. Second, Senna, Jodina and Larrea could have been used for fire starting. Anthracological analyses of the charcoal assemblages of Zoko Andi 1 demonstrated that during the initial Late Holocene the woody vegetation of this region was from a xerophytic open environment with xeric trees and shrubs and with trees and thick thorn scrub dotted by herbaceous gaps. This vegetation grew in an arid to semi-arid climate.