Résumé
The Cerrado biome supports a wide variety of arboreal and open vegetation physiognomies which were successively dominant through glacial and interglacial cycles. During the last glacial, corridors of biodiversity allowed Cerrado cold-adapted plant species to migrate between the Atlantic and Amazonian forests. Here, to characterize plant responses to Holocene climatic changes, we present a quantitative temperature and precipitation reconstruction for the last 15,000 years based on a new multiproxy record located in the central Cerrado. We show how the succession of the two events at 9300 and 8400 cal yr BP allowed the expansion of a wetcool-adapted tree taxa assemblage during ~1000 years followed by its retreat toward the landscape we know today. During these two events, our quantitative climate reconstruction showed a sudden increase of 100 mm in precipitation during the driest quarter (austral winter) and a 2°C decrease in mean annual temperature at 10°S latitude. The observed abrupt changes in biodiversity were linked to a negative southern Atlantic Subtropical Dipole during meltwater discharges in the North Atlantic causing a southward shift of the intertropical convergence zone mean position when it was at its northernmost position. Resulted in weaker Atlantic meridional overturning circulation, modified the interhemispheric heat exchange and increasing rainfall in the Northeastern Brazil. Our results show that the formation of a band of cold moisture in the southern tropics between eastern northeastern and northern central Brazil created a SW-NE corridor between the Caatinga and Cerrado biomes during the early Holocene that favored the mixing between Cerrado and Caatinga species.