1,400 years of biomass burning, climate variability, and environmental change on Ometepe Island, Lake Nicaragua

This study examines the relationship between short-term climate variability, paleo-fires, and anthropogenic sources of environmental change over the past 1,400 years on Ometepe Island, located in the tropical dry forests of southwestern Nicaragua. Macroscopic charcoal, loss on ignition, and magnetic susceptibility records were reconstructed from a lake sediment core, and statistical wavelet analyses were performed to contextualize natural fire regimes in this under-investigated tropical biome. Results from this project suggest that fire regimes on Ometepe Island respond to high frequency (sub-centennial scale) climate variations potentially due to the 11- and 22-year sunspot cycles and/or the El Niño Southern Oscillation, with dominant periodicities of ~7, 14, and 24 years. Results additionally support regional paleoenvironmental analyses by providing evidence of anthropogenic environmental impacts between ~600 and 1500 A.D. with a drastic decline after European contact, as well as evidence of widespread drought conditions between 800 - 1000 A.D. and 1150 – 1300 A.D.