Neotropical forest dynamics after deglaciation in the Central American Highlands: first anthracological results from El Gigante Rockshelter (11,000-1,000 BP), Honduras

Description

The mechanisms for the establishment of present-day vegetation during the early Holocene remain poorly understood in the Neotropics (American tropics), where paleoecological data are scarce and high biodiversity complicates forest dynamics. In Central America, understanding post-glacial forest expansion is further complicated by regional heterogeneity in temperature and humidity during and after the Younger Dryas, as recorded in speleothems and lake sediments. The few available pollen records covering the late glacial-Holocene transition reflect this variability, and the vegetation changes they reveal in the lowlands are therefore difficult to generalize on a regional scale. However, it is in the Highlands, today mainly covered by pine-oak forests, that Paleoindian hunter-gatherers first spread, followed by Mesoamerican horticulturalists in the Archaic and Formative periods (9,000-2,000 BP). Located at 1,300 masl in the mountainous interior of Honduras, El Gigante rockshelter gives a unique opportunity to examine postglacial dynamics of montane forests at a local scale using archaeological wood charcoal. The earliest occupation of the rockshelter by Paleoindian groups was dated to the final late glacial (11,000 BP). It was followed by intermittent phases of occupation until the Classic period (1,000 BP). The results of the anthracological study reveal an unprecedented forest dynamic, from post-glacial plant communities without modern analog to the establishment of present-day mixed montane forests. These changes in the woody cover contributes to better understand the paleoenvironmental context of human expansion in Central America from the Paleoindian period. They can be directly compared to the beginnings of horticulture, changes in hunting strategies, the rise and diversification of maize, and the development of the first farming villages in the region in the Late Formative (2,500-2,000 BP). This study is part of important issues in American prehistory, where the characterization of Neotropical primary forests and the understanding of human impact on the forests are highly controversial.

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