The Guaratuba watershed is located at the "Parque Estadual da Serra do Mar" and has its headwaters in the Atlantic plateau. The area has a gneissic bedrock in a parallel hilly relief with high slope gradient, covered by the Atlantic forest consisting mostly of low size trees. The climate is humid tropical with rainfall of 2,000 mm year-1, with no dry season. The predominant soils are Red Yellow Argisol (Typic Kandiudults or Paleudults and Typic or Lithic Hapludults) and Haplic Cambisol (Typic Dystropepts or Typic Haplumbrepts) with redoximorphic features. In this area, in a right angle transverse by across the greatest slope gradient, the association of Ferrocarbic Espodosol (Arenic Haplaquods or Typic Haplorthods) and Haplic Gleisol (Typic Haplaquents) laid over gneiss-altered material was studied as well as pebbles of fluvial origin and sands. The soils' evolution was also studied in detail along the topographic sequence. The soils of the area on a higher position and parallel to the bottom of the valley bottom, and the quartzose composition of the pebbles and sands indicate a fluvial deposition origin from a former fluvial plain that occurs today as an elevated terrace. These observations indicate that the soils were developed due to a succession of different environments, a dense forest vegetation (acid organic matter) and humid and hot climate, probably with dry season, in the beginning (Arenic Haplaquods or Typic Haplorthods development) followed by one with no dry season (greater humidity, Typic Haplaquents development), less dependent on parent material (pebbles and sands, and gneiss).
pedology; soil genesis; toposequence