INVESTIGADORES
LARA Ruben Jose
artículos
Título:
Holocene mangrove dynamics and sea-level changes in Taperebal, northeastern Pará State, northern Brazil
Autor/es:
VEDEL, V.; BEHLING, HERMANN; COHEN, MARCELO; LARA, RUBÉN JOSÉ
Revista:
VEGETATION HISTORY AND ARCHAEOBOTANY
Editorial:
Springer
Referencias:
Lugar: Berlin; Año: 2006 p. 115 - 123
ISSN:
0939-6314
Resumen:
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A
450-cm-long sediment core from Taperebal, in the mangrove region of
northeastern Pará State in northern Brazil has been studied by pollen analysis
to reconstruct mangrove development and dynamics and to infer relative
sea-level (RSL) changes during the Holocene. The chronology is based on six AMS
radiocarbon dates, starting at 10,000 14C yr BP.
Identified pollen and spores types were grouped into mangrove, Amazon rain
forest, restinga, other shrubs and trees, herbs and ferns. Based on changes in
the pollen assemblages and on cluster analysis, three pollen zones were
established. A patchy vegetation of coastal Amazon rain forest, restinga, salt
marsh and some mangrove, which was almost dominated by Avicennia, covered the study area between 9570 - 8430 14C
yr BP. The occurrence of an early Avicennia
dominated mangrove phase has not been reported so far from other sites in
northern Brazil. At that time the RSL reached nearly modern levels, but was
still low. Between 8430 and 5950 14C yr BP mangrove replaced mostly
the former coastal Amazon rain forest, restinga and some salt marsh vegetation
due to the rise of the RSL. Rhizophora
trees expanded markedly and Avicennia became rare, reflecting a RSL rise during this period. The full development of
mangrove is earlier than it has been reported from the other sites of the
northern Brazilian coast. In the sediment core there is apparently a gap
between 115 and 85 cm depth, possibly starting between 5900 and 5750 14C
yr BP. The upper deposits above 85 cm are of modern age and probably deposited
during the last decades. This gap can be explained by the decrease of the RSL
which is shown for other northern Brazilian coastal sites. The deposition of
mangrove sediments due the RSL rise after 4000 14C yr BP is not
found, probably due to the fact that the study site is located in the coastal
inland close to the upland area. The deposition of sediments during the last
decades, suggest that the modern RSL is high. Pollen data of these deposits
show that Rhizophora trees dominate
the mangrove forests, although Avicennia
trees increase slightly compared to the early-mid Holocene period, suggesting a
high RSL. Past anthropogenic activity seems to have had no marked impact during
the recorded period.
