The Saquarema archaeological site, on the Atlantic coast of the Rio de Janeiro State, is one of many shellmounds built on the Brazilian coast by hunter-gatherer populations during the Holocene. We used archaeological material from this site with the aim of evaluating the marine reservoir effect (MRE) in the region. Radiocarbon ages of 45 marine and 6 terrestrial samples from this shellmound provided data for assessing the MRE and the influences of freshwater and seasonal coastal marine upwelling in this specific locality. Samples of charcoal, fish otoliths, and mollusk shells were analyzed and the 14C dates were modeled in the OxCal platform to determine the marine reservoir correction. The result obtained is R = 265 ± 70 14C yr and the offset ΔR was found to be –140 ± 66 14C yr. To support the accuracy of this value for correcting conventional 14C marine ages, taxonomic analyses of the samples were performed.

The Amazon region holds a wide variety of ethnic groups and microclimates, enabling different interactions between humans and environment. To better understand the evolution of this region, ancient remains need to be analysed by all possible means. In this context, the study of natural and/or anthropogenic fires through the analysis of carbonized remains can give information on past climate, species diversity, and human intervention in forests and landscapes. In the present work, we undertook an anthracological analysis along with the 14 C dating of charcoal fragments using accelerator mass spectrometry (AMS). Charcoal samples from forest soils collected from seven different locations in the Amazon Basin were taxonomically classified and dated. Out of the 16 groups of charcoal fragments identified, five contained more than one taxonomic type, with the Fabaceae, Combretaceae and Sapotaceae families having the highest frequencies. 14 C charcoal dates span ~6000 years (from 6876 to 365 yr BP) among different families, with the most significant variation observed for two fragments from the same sampling location (spanning 4000 14 C yr). Some sample sets resulted in up to five different families. These findings demonstrate the importance of the association between anthracological identification and radiocarbon dating in the reconstruction of paleo-forest composition and fire history.

Plataformas orbitais Disponibilidade hídrica Crescimento de floresta KEYWORDS Orbital platforms Water availability Forest growth RESUMO: O município do Rio de Janeiro nas últimas décadas vem crescendo desordenadamente, principalmente pela falta de políticas públicas de urbanização, o que vem diminuindo a densidade de áreas verdes. Assim, a relação espectro-temporal fundamentada em três índices de vegetação do satélite Landsat 5 (Normalized Difference Vegetation Index-NDVI, Soil Adjusted Vegetation Index-SAVI e o Leaf Area Index-LAI) e dados de chuva de estações convencionais foram avaliados com testes e índices estatísticos com o objetivo de obter a melhor correlação entre eles para o município do Rio de Janeiro, RJ, Brasil. Os resultados não apresentaram normalidade e homogeneidade de variância dos dados baseados nos testes de Kolmogorov Smirnov e Shapiro Wilk-WS, e Hartley e Bartlet, respectivamente. Foram identificados altos valores do coeficiente de correlação de Pearson (r), seguidos de alta variabilidade significativa dos índices (NDVI, SAVI e LAI), nos anos de 1984, 1985, 1989 e 1991. O índice que melhor representou a relação no período estudado, em comparação aos demais, foi o NDVI, apresentando em 60% dos anos observados a maior correlação com a chuva. Portanto, ele pode ser utilizado em estudos da dinâmica da vegetação no município. A regressão linear entre os índices e a chuva nos perídos de 1990 e 1991 apresentam tendências negativas e positivas para os índices de vegetação.

No abstract