The Bola de Oro manteños and their resilience to climate change: chronological reconstruction of agricultural modifications through age-depth modelling and carbon abundance analysis

Abstract

A modified landscape of cultivation terraces and water retention ponds in the Chongón-Colonche Mountains in southern Manabí indicates a change in Manteño agricultural practices (ca. 650–1700 CE). This change over time must be understood as a social response to the scarcity and abundance of rainfall due to a constantly changing climate during the late Holocene. Results from excavation, radiocarbon dating, age-depth modelling, and charcoal abundance analysis as an indicator of fire use at three Manteño modifications identified via LiDAR and surveyed in the field at Bola de Oro Mountain support the following interpretations. Bola de Oro was occupied by the Manteños ca. 900 to 730 cal yr BP (1050–1220 CE) during constant droughts attributed to the Medieval Climate Anomaly (MCA). The implementation of stone-reinforced cultivation terraces begins ca. 610–545 cal BP (1340–1405 CE) and shows consistent use of fire through the 15th century. This robust investment was an adaptation to prolonged droughts and occasional extreme floods due to high instability in the El Niño-Southern Oscillation (ENSO) during the centuries between the MCA and the Little Ice Age (LIA). A pause in the use of fire during the 16th century indicates the return of humid conditions associated with the LIA. The rise of the use of fire marks the end of the occupation in the late 16th and early 17th centuries. All activity ceases during the 17th and 18th centuries until the return of the descendant populations during the second half of the 19th century. Manteño's success in an ever-changing climate can be attributed to their investment in transforming the territory's most resilient environment to prolonged droughts and extreme ENSO flooding into a human landscape.