Dry events, forest fires occurrences, Human displacement in Amazon and changes in carbon cycle during the upper Holocene
Renato
Campello
Cordeiro, Programa de Geoquímica UFF, rccordeiro@geoq.uff.br
(Presenting)
Bruno
Turcq, IRD/UFF, bturcq@geoq.uff.br
Abdelfettah
Sifeddine, IRD, sifeddin@umich.edu
In this work, we present evidences of fire occurrences during the Late Holocene recorded in two regions of the Amazon basin Carajas (PA) and Manaus (AM). These data will be compared with existing palynlogical and archeological records in Amazonia and CO2 record in Taylor Dome Antardida. In Carajas region charcoal deposition were estimated in lacustrine sediment records from South and North plateaus. In Manaus biomass and radiocarbon measurements of soil charcoal samples were investigated in a transect from upland to lowland areas of a tropical forest reserve. The fluxes of charcoal in the Lake N4 of the North Carajás plateau suffer increase at 1260, 730, 320-430, 140 yr 14C BP. High microcharcoal particles sedimentary fluxes were also observed in two cores of South Carajas plateau: in the lake 9, peaks of microcharcoal accumulation were observed at 1570, 930-820, 670 yr 14C BP. In the Lake 8, peaks were observed at 1040, 830-730 and 150 yr 14C BP. In the records obtained through quantification of the biomass and datation of the soil charcoals in the Manaus region, high charcoal biomass was dated at 1430, 1170, 890-340 yr 14C BP. Absy in a palynological study of five Amazon watershed lakes, showed the occurrence of dry periods in the latte Holocene sediments at around 4500 yr 14C BP, 2100 yr 14C BP, 1400 yr 14C BP and 1200 yr 14C BP, a marked dry phase around 700 yr 14C BP and a minor phase around 400 yr 14C BP. Archaeological studies across the Amazonian lowlands show discontinuities in cultural sequences, represented by different ceramic traditions at ca. 1400, 900, 650, 500 yr 14C BP. These events were coincident with changes in the CO2 variations recorded in Antartica ice core in the upper Holocene.
Submetido por Renato Campello Cordeiro em 18-MAR-2004
Tema Científico do LBA: CD (Armazenamento e Trocas de Carbono)