ANR PAST-FORCE

The ANR PAST-FORCE program focuses on interactions between pre-Columbian Maya societies, climate, and tropical forests at the interface between the southern Maya lowlands and the highlands, in northern Alta Verapaz, Guatemala. This piedmont zone, characterized by a humid tropical climate, features a vegetation gradient ranging from the dense tropical forests of the lowlands to montane cloud forests that combine boreal elements (pines, oaks, willows, liquidambars) with tropical taxa (Lauraceae, Meliaceae, etc.). Although these forests were heavily impacted by colonial deforestation and are now highly fragmented, almost nothing is known about their Holocene history due to the lack of paleoenvironmental studies in this region. From an archaeological perspective, this area was long considered marginal compared to the central lowlands, where major Maya cities of the Classic period (AD 250–950) are concentrated. Yet it is a key corridor for understanding ancient Maya history, as it served as a critical passage between the highlands and lowlands for the trade of lithic raw materials, particularly obsidian. Moreover, this is the region where the earliest city abandonments occurred as early as AD 750–800, marking the onset of what has been called the “Maya collapse,” which extended across the entire lowlands until the 11th century. The goal of PAST-FORCE is to reconstruct the history of these piedmont forests during the late Holocene in order to determine how climatic factors (paleo-precipitation) and human activities (deforestation and forest resource use) altered their floristic composition, structure, and extent. Linked to the Raxruha-Cancuén Regional Archaeological Project (MEAE, 2016–present) and the inter-MSH LACHUA-1 project (2024–2025), PAST-FORCE applies a regional paleoecological and archaeobotanical approach. The reconstruction of woodland cover dynamics relies on anthracological analysis at four Classic Maya sites — Cancuén, Raxruha, Chicoy, and Chama — combined with paleoecological study of Lake Lachua (sedimentology, palynology, fire history, and geochemistry) to examine the history of this forest socio-ecosystem and its disturbances, such as climate variability, agriculture, fuelwood use, and changes in wildfire regimes. This project thus has a dual ambition: to shed light on the history of Central American tropical forests and to illuminate the human history of a little-known region within the Maya area.

LSCE contribution: LSCE supports the chronological framework of the archaeological sites and paleoenvironmental reconstructions, and contributes the paleoenvironmental reconstruction component through isotopic organic geochemistry.