Thursday, 18 December 2014
Renato Campello Cordeiro1, Bruno Turcq2, Luciane Silva Moreira1, Renato de Aragão Rodrigues1,3, Fernando Lamego Simões Filho4, Gabriel Souza Martins5, Alice Bosco Santos1, Marcelo Barbosa6, Marcela Cardoso Guilles da Conceição5, Rodrigo de Carvalho Rodrigues5, Heitor Evangelista7, Patricia F Moreira-Turcq8, Yvaga Poty Penido1,5, Abdelfettah Sifeddine9 and José Seoane6, (1)Universidade Federal Fluminense, Niteroi, Brazil, (2)IRD, Bondy, France, (3)EMBRAPA Brazilian Agricultural Research Corportation, Agrosilvicultural, Campinas, Brazil, (4)CNEN National Nuclear Energy Commission, Rio de Janeiro, Brazil, (5)UFF Federal Fluminense University, Niteroi, Brazil, (6)UFRJ Federal University of Rio de Janeiro, Rio De Janeiro, Brazil, (7)UERJ Rio de Janeiro State University, Rio De Janeiro, Brazil, (8)IRD UFF, Bondy, France, (9)IRD Bondy, Bondy Cedex, France
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 reservoir in an intense land use change region. The records presented in this study were obtained in the following areas i) a reservoir in Alta Floresta region (northern Mato Grosso State); ii) Lago do Saci (southern Pará State), a lake close to Alta Floresta and located at the southern border of Pará State; iii) a bog in an ecotone area in the Humaitá region (southern Amazonas State); iv) lakes in lateritic iron crust of the Carajás Hills (southeastern Pará State); v) Lago Comprido, a floodplain lake close to the Amazon River and surrounded by tropical rain forest (Monte Alegre, Pará State; vi) Lagoa da Pata in the Morro dos Seis Lagos alkaline complex (São Gabriel da Cachoeira, Amazonas State) and vii) Lago Caracaranã, 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 Carajás 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 Caracaranã region where the savanna-type vegetation biomass is lower and thus generates less charcoal particles than forest ecosystems.