Recent plant history and fire regimes of the coastal peat bog of Chepu, Great Island of Chiloé, Chile

Abstract

The reconstruction of vegetation through pollen analysis and the fire regimes inferred from charcoal particles are of great
importance to the study of past climatic phenomena such as the Little Ice Age and the Medieval Warm Period. The aim
of this study was to reconstruct the vegetational history of the “Chepu” anthropic peat bog, located on the Great Island
of Chiloé in the Los Lagos Region of Chile, of the last millennium through palynological analysis and a high-resolution
analysis of macroscopic charcoal particles. This was done doing a stratigraphic boring in the center of the bog to conduct
the pollen analysis, obtain dating and quantify the macroscopic charcoal particles. The age model was obtained from three
radiometric datings and PB210 using the program MCAge. The results indicate that the fire patterns have been mainly
contingent upon the prevailing climatic conditions in the area, with consistency being observed in most cases between
local and extralocal fire events in the study area. This fire regime has influenced the abundance of species, indicating a
decrease of the arboreal component in periods of fire activity. Changes in the vegetation and fire activity are observed
through the pollen diagram of the last 2,000 years, associated mainly with variations in precipitation and likely with human
activity during the 20th century, respectively. Between 1960 and 1961 cal. AD in the profile, a change was observed in the
composition and abundance of plant taxa associated with the megathrust earthquake in Chile in 1960. The data contributed
by this profile are still insufficient to establish the extralocal climatic influence of events such as the Little Ice Age or the
Medieval Warm Period on Chiloé, but certain tendencies are observed.