Continental and coastal marine records of centennial to millennial changes in South American climate since the last glacial maximum

Interpreting the geological record of Amazon biomass combustion requires comparing charcoal accumulation rates in various biomes at different time scales. Charcoal accumulation rates, a proxy for palaeofire records, were obtained in sediment cores from Amazon lakes surrounded by several vegetation types and from a reservoirs in an intense land use change region. The records presented in this study were obtained in the following areas i) a reservoirs in Alta Floresta region (northern Mato Grosso State); ii) Lago do Saci (southern Pars State), a lake close to Alta Floresta and located at the southern border of Para State; iii) a bog in an ecotone area in the Humaita region (southern Amazonas State); iv) lakes in lateritic iron crust of the Carajas Hills (southeastern Para State); v) Lago Comprido, a floodplain lake close to the Amazon River and surrounded by tropical rain forest (Monte Alegre, Para State; vi) Lagoa da Pata in the Morro dos Seis Lagos alkaline complex (Sao Gabriel da Cachoeira, Amazonas State) and vii) Lago Caracarana, a secluded lake in the northern Amazon cerrado (Roraima State). The highest charcoal accumulation rates were observed for modern records related to an intense change in land use at Alta Floresta, which had no precedent during the Holocene history of the Amazon. High charcoal accumulation rates that were observed in the Carajas region during low lake level phases in the Amazon in the mid-Holocene were comparable to those at the onset of the human settlement in Alta Floresta region. An increase in charcoal accumulation rate was observed in the late Holocene when the lake level was high, suggesting an interaction between climates and human presence. Low charcoal accumulation rates are typical of modern high rainfall environments, as observed in Lagoa da Pata where the environment is not susceptible to occurrences of wildfires even during relatively drier climatic phases. Low charcoal accumulation rates also exist in the relatively dry cerrado (savanna type) biome even during relatively dry phases in the Caracarana region where the savanna-type vegetation biomass is lower and thus generates less charcoal particles than forest ecosystems