Inferências sobre Vegetação e Clima no Holoceno a partir de Fitólitos e Pólen da Lagoa do Macuco, Litoral Norte do Estado do Espírito Santo (Brasil)

[EN] An interproxy approach focused on phytoliths and pollen, including radiocarbon dating and sediment particle-size analyses, has been carried out at Lagoa do Macuco, Linhares municipality, Espírito Santo State, Brazil. Three pollen zones were identified: the first one (MAC-C I) indicates the presence of mangrove vegetation between 7700 cal yr BP and 4396 cal yr BP; the second one a displacement of the vegetation from the lower areas to the more elevated margins of the valley (MAC-C II, from between 4396 to 1287 cal. yr BP) and third one (MAC-C III), representing the period of the current lake evolution, between 1287 cal. yr BP and the present day. The displacement of the mangrove seems to be connected to the landward migration of the palaeo-estuary and the flooding of the lower parts of the valley, reflecting the relative sea-level highstand, which occurred after 7000 cal yr BP. The phytolith analysis indicated four main zone. The phytolith zone I (7700-7100 cal yr BP) did not show the presence of phytoliths. The phytoliths zone II (7100-3400 cal yr BP) indicates the presence of an open vegetation predominantly of grasses while phytolith zone III (3400-400 cal yr BP) shows a phase with more forested vegetation. Finally, the phytolith zone IV (400 cal yr BP to modern) has a decrease in tree cover and the setting of vegetation with a strong grasses component. Phytoliths indices indicate trends of humidity and temperature at a more local scale, allowing understanding the environmental conditions during the formation of the current lake.[PT] Uma abordagem interproxy focada na análise de fitólitos e de grãos de pólen, também incluindo datação 14C e análise granulométrica de sedimentos, foi aplicada ao estudo da Lagoa do Macuco, em Linhares no Estado do Espírito Santo. Foram identificadas três zonas polínicas definidas com base nas mudanças do registro polínico, a primeira (MAC-C I) indicando a presença de uma vegetação de mangue entre 7700 anos cal AP e 4396 anos cal AP, a segunda (MAC-C II) que representa o deslocamento da vegetação das áreas mais baixas para as partes marginais mais elevadas do vale (4396 anos cal AP - 1287 anos cal AP) e a terceira (MAC-C III) que representa o período da instalação do atual lago, entre 1287 anos cal AP e os dias atuais. O deslocamento do mangue parece estar conectado a migração em direção ao paleo-estuário e o alagamento das partes baixas do vale, refletindo a elevação do nível relativo do mar depois de 7000 cal anos AP. A análise fitolítica indicou quatro zonas principais. A zona fitolítica I (7700-7100 anos cal AP), não apresentou fitólitos. A zona fitolítica II (7100-3400 anos cal AP) indica a presença de uma vegetação predominantemente composta por gramíneas, enquanto a zona fitolítica III (3400-400 anos cal AP) mostrou uma fase com uma vegetação mais florestada. Finalmente, a zona fitolítica IV, (400 anos cal AP até os dias atuais) apresentou decréscimo da cobertura arbórea e uma estrutura de vegetação com forte presença de gramíneas em sua composição. Os índices fitolíticos indicaram tendência de umidade e temperatura em escala local permitindo a compreensão das condições ambientais durante a formação do lago atual.The authors express their gratitude to Vale and Sooretama Nature Reserves (Linhares, ES, Brasil) for the field support. This work received financial support by the São Paulo Foundation for Research (FAPESP), grant 2011/00995-7, and CNPq (Universal), grant 470210/2012-5.Peer Reviewe

Estudos paleoambientais interdisciplinares: dinâmica da vegetação, do ambiente marinho e inferências climáticas milenares a atuais na Costa Norte do Espírito Santo, Brasil

Estudos paleoambientais desde ~50.000 anos na costa do Brasil e, em particular, no litoral do Espírito Santo, são ainda insuficientes para servir de base a reconstituições da dinâmica da vegetação, de oscilações do nível relativo do mar e de flutuações climáticas e respectivas influências sobre a ação humana milenar. Para obter essas informações, uma equipe interdisciplinar, financiada por projetos temáticos FAPESP e CNPq, desenvolveu pesquisas correlatas na Reserva Natural Vale (RNV) e região. Para a caracterização da dinâmica da vegetação e marinha, com inferências climáticas, em locais de floresta de tabuleiros e campos naturais da RNV e região desde ~16.000 anos, utilizaram-se isótopos do C (12C, 13C e 14C) da matéria orgânica do solo e sedimentar, além de palinologia em sedimentos lacustres e terrestres. No estudo da dinâmica do ecótono floresta – campo, apresentam-se inferências preliminares sobre a evolução pedogenética dos Espodossolos associados ao campo, com ênfase às suas características físico-químicas, e também dos Argissolos, encontrados sob floresta. Finaliza-se com o estágio inicial de uma coleção de referência de fitólitos, bioindicador de vegetação utilizado em estudos paleoambientais, extraídos de plantas da floresta de tabuleiros da RNV.A equipe agradece todo o empenho dos funcionários e apoio logístico da Reserva Natural Vale, Linhares, Espírito Santo; à FAPESP através do projeto Temático 2011/00995-7 (ProjES); e ao CNPq – Universal 2012-5/470210, pelo aporte financeiro e a colaboração dos técnicos do Laboratório 14C, Liz Mary Bueno de Moraes e Thiago Casemiro Barrios de Campos, na preparação de amostras gasosas para a datação 14C.Peer Reviewe

Potential of soil phytoliths, organic matter and carbon isotopes for small-scale differentiation of tropical rainforest vegetation: A pilot study from the campos nativos of the Atlantic Forest in Espírito Santo State (Brazil)

A truthful vegetation reconstruction is essential for understanding the historical trajectory of climate change and as well as the nature and extent of human impact on ecosystems. A classical approach to these studies is the use of pollen to identify flora composition and variability over time. However, the use of pollen is not always viable due to lack of depositional environments and general taphonomic processes, such as edaphic conditions. The most durable plant fossils, with widespread presence in diverse depositional realities, are phytoltihs. These proxies are common, well preserved in soils and with great potential for the detection of vegetation signals at micro and meso-level. Therefore, phytoliths are an important tool for recognising variability in major biomes such as tropical forests. In this study we illustrate the results of a pilot project in the Atlantic Forest (Mata Atlântica) of Brazil. The Atlantic Forest is a very diverse ecosystem and its environmental history is still poorly known, especially in relation to the origin and development of non-forested islands (campos nativos) within the forest. Campos nativos create a mosaic with the Mata Atlântica and their current persistence is due to a combination of topographic effects, hydrology and soil. Our work evaluated the potential of soil phytolith, total organic content (TOC) and δC of two grassland/savannah campos nativos in the Vale Nature Reserve in Linhares (state of Espírito Santo). The results from isotopic analysis show the relevance of C3 plants since the beginning, and for all the sedimentary history, in both campos nativos. The soils of the nativos are spodosols and, surprisingly, the phytolith composition has been drastically affected by the edaphic conditions. The phytolith assemblages are often impoverished, especially in the soil sandy layer. However, the assemblages still show an important local floristic component (micro scale) with an input from the surrounding vegetation (meso-scale).We acknowledge the FAPESP funding (Projeto Temático 2011/00995-7 – ProjES) and CAPES funding (CAPES PVE A115/2013)Peer Reviewe

Palaeovegetation and palaeoclimate dynamics during the last 7000 years in the Atlantic forest of Southeastern Brazil based on palynology of a waterlogged sandy soil

Mineral soils are usually considered inappropriate for pollen analysis because of the poor quality of pollen and spore preservation and the disturbed stratigraphy. However, here we present a 57 cm core, collected from a waterlogged sandy soil in the lowland Atlantic Forest of SE Brazil, which shows good stratigraphy and good preservation of pollen and spores since ~7000 cal. BP, both in organic and in mineral horizons. By the other hand, the decomposition of the organic matter and its translocation along the soil profile led to changes of C and N results (TOC, TN, C/N, δ13C and δ15N). Mid-Holocene palaeoclimate inferences from this study are in accordance with climate fluctuations presented in previous studies for Central, Southeastern and Southern Brazil, when a change to more humid climate occurred at ~7000 cal BP. The process responsible for the presence of biological proxies along this sandy soil profile involves the continuous deposition of these proxies together with litter and sand, and the subsequent decomposition of the litter. Ultimately, this process led to the vertical accretion of the sand with the more resistant organic structures preserved in stratigraphic sequence. The preservation of pollen and spores along the profile is probably caused by low pH and redoximorphic conditions due to water saturation. This study suggests the potential for retrieving useful palaeoecological information from mineral and organic horizons of tropical waterlogged sandy soils, which is especially useful for those regions where traditional pollen archives (lakes and peat bogs) are absent

Late Holocene mangrove dynamics of the Doce River delta, southeastern Brazil: implications for the understanding of mangrove resilience to sea-level changes and channel dynamics

This work aims to understand mangrove resilience to changes in a wave-influenced delta in southeastern Brazil during the late Holocene using an integrated analysis of palynology, sedimentology, and geochemistry (δ13C, δ15N, C:N and C:S ratio), and radiocarbon dating on two sediment cores. The data indicated three mangrove succession phases: 1) an estuarine point bar/tidal flat occupied by a mixture of mangrove species (~2660 - ~2050 cal yr BP); 2) a tidal flat dominated by Laguncularia mangroves (~2050 - ~900 cal yr BP); and 3) tidal flats with Laguncularia mangroves upstream and establishment of Rhizophora/Avicennia mangrove at the river mouth (~900 cal yr BP until present). The geochemical results suggest a dominance of C3 terrestrial plants with a mixture of C4 plants and organic matter of marine/estuarine origin throughout the late Holocene. Laguncularia and Rhizophora trees were established since ~2660 cal yr BP as pioneers, followed thereafter by Avicennia. Currently, tidal flats upstream are occupied by mangroves mainly represented by Laguncularia. Rhizophora/Avicennia mangroves occur at the mouth of the river. The relative sea-level fall during the late Holocene, as well as the channel dynamics, caused the development of tidal flats and mangrove succession inland. The succession of Rhizophora, Laguncularia, and Avicennia, followed by the permanence of only Laguncularia, is likely related to the resilience of each mangrove genus to habitat disturbance (e.g., salinity and sediment grain size fractions) caused by sea-level changes and channel dynamics. Our results show that mangroves may be resilient to the effects of Atlantic sea-level fluctuations, but the floristic structure in the past is different from that of today

Archaeological hunting patterns of Amazonian horticulturists: The Guarani example

We analyse the hunting patterns based on faunal records of horticultural groups fromthe Atlantic Forest grouped in the Guarani archaeological unit, which are the materialand behavioural expression of populations of Amazon origin who practiced slash‐andburnagriculture in the Atlantic Forest of Argentina, Brazil, Uruguay, and Paraguay.The analysed temporal block ranges from ca. 1373 to 1698 of the Common Era.The characteristics of the faunal assemblages are the high level of the taxa richnessand the equitability, where no taxa predominate over the others. The capture decisionwas probably guided primarily by the weight of the potential prey (preferentiallyterrestrial mammals) considering thresholds above 10 kg per individual, which haveprovided the greatest biomass. Nevertheless, small preys are numerically importantand taxonomically very diverse. Fish mostly comprise small individuals, with no taxonomicselectivity. The hunted animals were transported completely to the villages.Terrestrial prey and fish were preponderantly boiled in ceramic containers. All thebest ranked preys locally available were hunted, so in the long term, there were noexceptions to consumption. The hunting strategies are concordant with historicaland ethnographic observations that include a broad diet with low taxonomic selectivity,small foraging range, and garden hunting.Fil: Acosta, Alejandro Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Secretaría de Cultura de la Nación. Dirección Nacional de Cultura y Museos. Instituto Nacional de Antropología y Pensamiento Latinoamericano; ArgentinaFil: Carbonera, Mirian. Universidade Comunitária da Região de Chapecó; BrasilFil: Loponte, Daniel Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Secretaría de Cultura de la Nación. Dirección Nacional de Cultura y Museos. Instituto Nacional de Antropología y Pensamiento Latinoamericano; Argentin