Late Quaternary vegetation, fire and climate dynamics of Serra do Aracatuba in the Atlantic coastal mountains of Parana State, southern Brazil

Late Quaternary vegetation, fire and climate dynamics were studied by pollen and charcoal analysis on a sediment core from near the summit of the Serra do Aracatuba at 1500 m elevation, part of the Serra do Mar coastal mountains of Parana State, southern Brazil. Three radiocarbon dates indicate that clay and peat were deposited in a shallow basin during the last 14,880 (B.P). Accumulation was probably continuous, but sedimentary gaps during the dry mid Holocene cannot be excluded. During late-glacial times the upper coastal mountain were covered with grassland, reflecting relatively dry and cold climatic conditions. Large areas of natural grasslands remained in the upper mountain region during the Holocene. Only after 2000 (B.P). did Araucaria forest trees, specially Ilex, some Atlantic forest trees as well as the pioneer Myrsine move to higher elevations, reflecting markedly wetter climatic conditions. This expansion stopped and the forest areas were reduced significantly by human activities during about the last 200-300 years. The modern grassland vegetation of the uppermost mountains may reflect the natural setting, but may also partly result from post-Columbian human activities. Fires were rare during the late Pleistocene and even less frequent during the early and mid Holocene. During the wettest recorded period of the late Holocene fires increased markedly and are therefore most probably of anthropogenic origin.