Estudo interdisciplinar em sedimentos lacustres da região sul do estado de São Paulo. Reconstrução da vegetação e do clima no Quaternário tardio / Interdisciplinary study of lacustrine sediments from Southeastern São Paulo state (Brazil). Late Quaternary vegetation and climate changes

AUTOR(ES)

Jaime Rissi Passarini Junior

DATA DE PUBLICAÇÃO

2009

RESUMO

One sediment core collected at the margins of a lake surrounded by Atlantic rainforest vegetation at Parque Estadual do Alto Ribeira (PETAR), southern São Paulo state (Brazil), was analyzed, in order to reconstruct the history of the local vegetation over the last 2500 years. Elemental (Total Organic Carbon TOC and Total Organic Nitrogen), isotopic (C and N), pollen analysis and radiocarbon dating were integrated on this work. Also was made a comparison of two protocols for Quaternary pollen chemical treatment. The tested protocols were proposed by Faegri and Iversen, 1989 (Protocol 2) and by Colinvaux et al., 1999 (Protocol 1). The comparison methods developed in this study checked the protocols performance on the quantity of palinomorphs and of organic matter found in 450 random areas of microscope slides of each protocol. The time consuming, laboratory routine, costs and residue production by the protocols were considered for comparison. Five samples were used for comparison and the Protocol 1 showed an average of 10% less organic matter and more palinomorphs than Protocol 2. According to the isotopic and pollen results, the study area vegetation maintained as a forest for the last 2500 years BP. delta13C values of -29%o indicated the presence of C3 plants during all the sediment study and a isotopic enrichment (- 24,9%o) was observed between 1650 and 1480 yrs BP. Pollen analysis suggested the occurrence of colder climatic conditions between 2550 and 2000 yrs BP and a warmer and humid period was suggested between 1000 and 680 yrs BP. Charcoal particles were found since 2550 yrs BP indicating paleofire probably associated to the human activities

ASSUNTO(S)

isótopos carbono (c-12 c-13 c-14) e nitrogênio floresta atlântica sedimentary organic matter paleovegetação stable isotopes (c n) carbon (c-12 c-13 c-14) and n isotopes atlantic rainforest quaternário tardio matéria orgânica sedimentar pollen analysis protocol pólen palaeoenvironment late quaternary

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