Late quaternary vegetational and climatic changes in cerrado and palm swamp from central Brazil

Geochemical and palynological analyses of core CR1 from Crominia, Goias, provided information on the paleoenvironmental history of central Brazil. The records show that prior to 32,400 yr B.P. the vegetation of the Crominia region was similar to the present one characterized locally by a complex of cerrado, gallery forest and palm swamp, indicating a semi-humid tropical climate. A palm swamp occupied the coring site. From 32,400 to about 20,000 yr B.P. a treeless grassland replaced the arboreal cerrado and the gallery forest suggesting that humidity increased but temperature probably decreased. The site was a shallow lake between ca. 27,000 and 20,000 yr B.P. Humidity started to decrease at ca. 18,500 yr B.P. was very dry. A sparse vegetation was growing in the region during that time. The dry climate continued until 6500 yr B.P. and the core site probably dried out several times. At ca. 5000 yr B.P. humidity increased again, the palm swamp vegetation returned to the site and cerrado vegetation and gallery forest started to grow in the region. The abundant charcoal particles prior to 20,000 yr B.P. and from 10,500 to ca. 3500 yr B.P. document a long history of fires in the region. Results are compared with those from other sites in central Brazil and with the climate sequence of the last glacial maximum and postglacial time in the tropical Andes. (Résumé d'auteur

Late quaternary vegetational and climatic changes in cerrado and palm swamp from central Brazil

Geochemical and palynological analyses of core CR1 from Crominia, Goias, provided information on the paleoenvironmental history of central Brazil. The records show that prior to 32,400 yr B.P. the vegetation of the Crominia region was similar to the present one characterized locally by a complex of cerrado, gallery forest and palm swamp, indicating a semi-humid tropical climate. A palm swamp occupied the coring site. From 32,400 to about 20,000 yr B.P. a treeless grassland replaced the arboreal cerrado and the gallery forest suggesting that humidity increased but temperature probably decreased. The site was a shallow lake between ca. 27,000 and 20,000 yr B.P. Humidity started to decrease at ca. 18,500 yr B.P. was very dry. A sparse vegetation was growing in the region during that time. The dry climate continued until 6500 yr B.P. and the core site probably dried out several times. At ca. 5000 yr B.P. humidity increased again, the palm swamp vegetation returned to the site and cerrado vegetation and gallery forest started to grow in the region. The abundant charcoal particles prior to 20,000 yr B.P. and from 10,500 to ca. 3500 yr B.P. document a long history of fires in the region. Results are compared with those from other sites in central Brazil and with the climate sequence of the last glacial maximum and postglacial time in the tropical Andes. (Résumé d'auteur