Contribution to the Holocene history of Atlantic rain forest in the Rio Grande do Sul state, southern Brazil

Abstract

This is a paleoclimatic synthesis based on the results of seven cores from the Brazilian Coastal Plain and adjacent low areas (Central Depression and Serra Geral, southern foothill valley) of Rio Grande do Sul, published by different authors. The objective is asses to the Holocene history of the Atlantic rain forest stricto sensu (str. s.), a dense ombrophilous forest in the extreme southern Brazil. The comparative analysis indicates scarce presence of the first taxa of the Atlantic rain forest str. s. at the beginning of the Holocene (probably due to warmer and wetter climate) and sea-level oscillations. Subsequently marsh forest expansion took place after 4,000 BP on the coast, after sea regression and desalination of the soils. In the adjacent low areas from the coast, favored by this warmer and wetter climate without marine influence, expansion of the forest seems to have occurred earlier, at about 4,000 BP. In the Serra Geral southern foothill valleys and Central Depression forest expansion occurred much earlier, at ca. 6,000 BP. These data agree with the coastward migration of the Atlantic rain forest str. s. from inner continental areas colonizing the Coastal Plain of southern Brazil in the Late Holocene.