This thesis is aimed to study the paleoecology of the southern Gran Sabana region (GS; SE Venezuela) since the Late Glacial to the present. This region is characterized nowadays by the occurrence of large extent of savannas in a climate suitable for rainforests. For this purpose, three sequences (two from peat bogs and one from lake sediments) have been analyzed for pollen and spores, non-pollen palynomorphs (NPP), and microscopic charcoal particles. Among the sequences analyzed, two of them are located currently within treeless savannas (Lakes Chonita and Encantada); whereas the third one is placed in the boundary between GS savannas and Amazon forests (El Paují). The Late Glacial interval of Lake Chonita was characterized by a shrubland that was replaced by a treeless savanna at the end of Younger Dryas (YD) and the onset of the Holocene, linked to the occurrence of regional fires since ca. 12.4 cal kyr BP. The beginning of local fires was dated synchronous with the vegetation replacement, ca. 11.7 cal kyr BP. A similar shrubland, though not identical, is located nowadays around 200 m elevation above the lake, so the replacement by surrounding savannas was interpreted as a probably upward displacement of the former vegetation and an increase in average temperatures of approximately 0.7 - 1.5ºC. This section represents the oldest interval analyzed for GS so far, and the presence of fires during the Late Pleistocene is among the oldest fire records documented for northern South America. The peat bog records of Lake Encantada and El Paují showed the main vegetation trends of the last 8 cal kyr BP, which were characterized by the continuous occurrence of regional fires. In Lake Encantada, the presence of treeless savannas was reported during the whole interval analyzed as the dominant vegetation type, despite variations in forest abundance and composition taxa of the community also occurred. The vegetation changes in this record were interpreted as mainly due to climatic shifts until the Late Holocene. At El ...