Fire is a dominant ecological force known to transform landscapes, as it shapes vegetation cover and selects for fire-adaptive traits across plants in long timescales. Brielle Canares, recent MS graduate from EARTH and UMMP, tested for the occurrence of fires in a Paleocene Neotropical rainforest found in central Colombia. Even though rainforests and fires do not seem consistent with each other, charcoal fragments suggestive of fires had been reported from the same rock units that plant fossils came from.
Brielle focused her MS research project into testing for the occurrence of fire using fire-specific biomarkers, specifically polyaromatic hydrocarbons (PAHs). These are organic compounds formed from the combustion of wood and plant material, and readily preserved in sedimentary rocks. Additionally, Brielle looked into what type of vegetation was present at the time, using phytoliths, which are microscopic silica bodies that form inside plant cells and can be used to identify certain groups of plants.
Brielle found fire-related biomarkers that confirmed the frequent occurrence of fire, as well as etched phytoliths in sediments that predate the rainforest leaf assemblages. The phytoliths also showed the occurrence of grasses, palms, woody flowering plants and conifers. These findings seem to suggest evidence of disturbance by fires during the early assembly of Paleocene Neotropical rainforests. The question that remains is, why did fire frequence subside?
