Phytoliths to apPROXYmate Maya landscapes over early Anthropocene : case of Naachtun tropical wetland.

Abstract

Reconstitutions of past anthromes in the tropical karstic environments of the Central Maya lowlands (CMLs) are generally restrained by bioindicators such as pollen in the rare lakes and perennial wetland systems and charcoals. This original work mobilizes phytoliths and, to a lesser extent, other bioindicators such as molluscs and diatoms. It contributes to demonstrate of these fossils potential to participate in the reconstruction of the Maya society-environment interactions, in the CMLs Elevated Interior Region. We studied swamp and lake sediment archives of a karst polje (nammed bajo El Infierno), located north of the regional Maya city of Naachtun. These bioindicators were studied on three sediment series covering the last 3500 years, during which this region was settled by the Maya. This multiproxy and multi-local approache allowed to propose an environnemental history for this wetland. It shows multi-millennial anthropogenic impacts in the bajo. The local opening of the swamp forest suggests the occupation of this bajo during the early Preclassic. The bioindicators also provide information on the variability of lake conditions, marked in particular by perennial shallow lake dynamics during the middle Preclassic, which provided a resource for the Maya. The direct trace of maize agriculture and pervasive herbaceous formations through the bajo are finally noted during the late Preclassic. Demographical and political disruptions occurred to Naachtun during the Preclassic-Classic transition, simultaneous to regional droughts. The Classic is marked by the presence of an environmental mosaic which may indicate a change in bajo land use. This landscape diversity demonstrates a new time the need to carry out multi-local paleoecological approaches to understand the society-environment interactions. Phytoliths, by their siliceous mineralization and local expression, seem appropriate to become an essential tool for these approaches in the CMLs.