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In order to reconstruct the vegetation history of the last 10.000 years, palynological analyses were carried out using 17 sedimentary samples of a core drilled in Parque Estadual do Rio Doce (PERD-MG). Twenty-one species of fern spores, 52 species of pollen grains and six species of fungi were identified. Phase 1 (10.375 - 9.350 cal. years BP) is characterized by a low concentration and diversity of pollen grains and is thus interpreted as a fluvial system with the presence of coarse-grained sediments. Phase 2 (9.062 - 8.195 cal. Years BP) is interpreted as a transition from a fluvial to lacustrine environment. Phase 3 (7.905 - 4.785 cal years BP) is characterized by increased trend of palynomorph concentration, highlighted by a high abundance and diversity of fern spores, which are indicative of a more a humid condition. The uppermost phase, Phase 4 (4.785 - 50 cal. Years AP), possessed a lower abundance of herbaceous flora, which is replaced by other vegetation groups (e.g. marsh, cerrado, Atlantic Forest). The uppermost sample represents the contemporary environment (~50 years), which is characterized as seasonally-flooded.

Organic carbon isotopic composition (δ13Corg) in loess deposits is an important indicator of terrestrial paleovegetation, and it has been widely used for paleoenvironmental reconstruction in aeolian sediments around the world. However, little research has been done on the variation and paleoenvironmental implication of δ13Corg from loess deposits on Shengshan Island, East China Sea, during the last glacial period (LG). In this research, we present optically stimulated luminescence (OSL) ages, total organic carbon (TOC) data and δ13Corg records of the loess section at Chenqianshan (CQS) on Shengshan Island. Additionally, to study the effectiveness of δ13Corg in documenting paleoenvironmental changes, magnetic susceptibilities and diffuse reflectance spectra were surveyed. TOC concentration for the CQS loess section ranged from 0.11% to 0.47%, and the δ13Corg composition of the CQS loess section varied between −20.80‰ and −24.56‰ during the LG. The average value of C4 abundance was 21.31%. TOC, δ13Corg, χfd, and Hm/(Hm + Gt) curves for the CQS loess section showed similar patterns. The results of our study indicated that the vegetation of the CQS loess deposit was mainly C3/C4 mixed vegetation, and C3 vegetation was the most important vegetation. The comparison between the δ13Corg curve for the CQS section and other existing δ13Corg records of the loess sections from central and northern China showed similar trends and their vegetation succession exhibited synchronous change during the LG. Based on a comparison of the δ13Corg record, C4 abundance and χfd of the CQS section and other global geological records, it was concluded that the mutual effects of precipitation and temperature caused the change of paleovegetation in loess deposits on islands in the East China Sea during the LG.

We examine δ13C values from soil organic matter (SOM) from the Culebra, Inguiro and Verde watersheds (Verde data are from Mueller et al., 2012) located in the Mixteca Alta from the terminal Pleistocene to the present. The SOM δ13C values were compared against local paleosol data and other paleoenvironmental proxies from central and southwestern Mexico. The paleovegetation implications of the SOM reflect overall changes in paleoclimate from the terminal Pleistocene through the middle Holocene. The late Holocene stable carbon isotope values varied widely, suggesting that human activities such as agriculture affected the paleoenvironment and paleovegetation in the study area, similar to findings in central Mexico. Values of δ13C show a significant rise between 3500 cal BP and 1250 cal BP, with one notable cluster of enriched values corresponding to the Post-Classic cultural period (local Natividad phase, 1250–500 cal BP), when the local population is thought to have peaked over 100,000. Since the late Formative period (local late Cruz phase, starting ∼3500 cal BP), lama-bordo (i.e., sediment check-dams) and agricultural terrace constructions were important for land use management and agriculture, which became widespread by the Post-Classic period. The highly enriched values associated with widespread agricultural structures suggest the increased importance of maize cultivation, and potentially the increased significance of CAM plant management, such as maguey and nopal during the late Holocene.

Phytoliths are a reliable paleovegetation proxy and have made an important contribution to paleoclimatic studies. However, little is known about the depositional processes affecting soil phytoliths, which limits their use for paleoclimate and paleovegetation reconstructions. Here, we present the results of a study of the vertical translocation characteristics of phytoliths in 40 natural soil profiles in Northeast China. The results show that phytolith concentration decreases within the humic horizon of the soil profiles and that ∼22% of the phytoliths are translocated below the surface of the studied soils. In addition, we find that the translocation rate of phytoliths varies markedly with phytolith type and that phytolith size and aspect ratio also have a significant effect. Phytoliths with length >30 μm and with aspect ratio >2 and those with length 25 μm and aspect ratio

Paleoenvironmental and paleoclimatic variations experienced by the Mediterranean region during the Miocene Burdigalian-Langhian interval have been investigated through analysis of biomarker signals (n-alkanes and glycerol dialkyl glycerol tetraethers, GDGTs) from slope mudstones of the northern Apennines (Marne di Vicchio Fm). Terrestrial signatures in marine sediments reflected by preserved long-chain n-alkanes with a identifiable odd-over-even carbon number predominance attest to the thermal immaturity of the sedimentary rock. Abundances of n-C27, n-C29 and n-C31 alkanes, coupled with the carbon isotopic signatures of the n-C31 homologue suggest that Mediterranean vegetation crossed a transition phase adapting to arid conditions that may favored a shift from woodland to wooded grassland during the Middle Miocene. This ecosystem evolution could have been favored by the passage from warm humid conditions to a warm drier climate, as indicated by GDGT-based TEX86 and BIT indexes. Strong similarities between these Mediterranean biomarker records and those from the Atlantic (DSDP Sites 94, 516, 608) imply a constant connection of the western Mediterranean to the Atlantic Ocean from ~19 Ma to ~14.5 Ma.

Pollen analysis was done on lacustrine sedimentary sequences dated by micromammals as late Pliocene–early Pleistocene that outcrop in two Neogene graben basins from SW Turkey. This study shows vegetation changes from steppe-like to more forested environments, very similar to the cyclic oscillations related to late Pleistocene glacial–interglacial climate changes. Artemisia was abundant during cold–arid periods, indicating that this species was already widespread in this area during the latest Pliocene and the beginning of the Pleistocene. A review of pollen records from Anatolia agrees with this study, suggesting that the spreading of this arid species occurred during a major climatic change: the beginning of the first glaciations and probably a change in seasonality towards summer aridity. Artemisia temporarily disappeared from the region during warm–wet periods and thus we suggest that glacial–interglacial-type oscillations already occurred in the area during the late Pliocene–early Pleistocene.

Pollen of middle Oligocene to early Miocene age from core sediments from the New Jersey Shallow Shelf (Atlantic Coastal Plain: IODP-Expedition 313, Site M0027A), was analyzed using light- and scanning electron microscopy, and a pollen-based bioclimatic analysis was performed. The microflora is dominated by Quercus pollen. Pollen ornamentations indicate that Quercus pollen most likely originated from species of sections Quercus, Lobatae, Quercus/Lobatae and aff. section Protobalanus. Eotrigonobalanus, an extinct Fagaceae lineage, was present in the coastal plain. Relative abundances of several tree taxa (e.g., Carya) did not change significantly between the Oligocene warm phases, but contrast to late middle Miocene (comprising most of the Langhian and Serravallian) records from the same area. By assigning terrestrial palynomorphs to paleovegetation units, topographic movements of these units were identified. The mesophytic forest was the most widespread and zonal vegetation type in the hinterland through the analyzed interval. Periodic changes in the relative abundances of paleovegetation units suggest altitudinal vegetation movements responding to global climate change. Observed movement signals are generally weak, but increases in bisaccate pollen, representing spread of high- and mid-latitude forest, probably reflect the onset of cold intervals such as cooling phases at ~ 29.1, ~ 28.5, and 23.5 Ma. Spread of edaphically controlled forest formations during regression phases also indicates climate change. The onset of the Mi-1 event at ~ 23.03 Ma is probably reflected by a decrease in pollen-inferred paleotemperatures, although the event itself occurred during a sedimentation hiatus. Pollen-based paleoclimate reconstructions indicate long-term stability in temperature and precipitation within the humid warm temperate zone.

Premise of the study DNA may be preserved for thousands of years in very cold or dry environments, and plant tissue fragments and pollen trapped in soils and shallow aquatic sediments are well suited for the molecular characterization of past floras. However, one obstacle in this area of study is the limiting bias in the bioinformatic classification of short fragments of degraded DNA from the large, complex genomes of plants. Methods To establish one possible baseline protocol for the rapid classification of short-read shotgun metagenomic data for reconstructing plant communities, the read classification programs Kraken, Centrifuge, and MegaBLAST were tested on simulated and ancient data with classification against a reference database targeting plants. Results Performance tests on simulated data suggest that Kraken and Centrifuge outperform MegaBLAST. Kraken tends to be the most conservative approach with high precision, whereas Centrifuge has higher sensitivity. Reanalysis of 13,000 years of ancient sedimentary DNA from North America characterizes potential post-glacial vegetation succession. Discussion Classification method choice has an impact on performance and any downstream interpretation of results. The reanalysis of ancient DNA from glacial lake sediments yielded vegetation histories that varied depending on method, potentially changing paleoecological conclusions drawn from molecular evidence.

International audience; The main objective of this paper is to provide researchers that investigate fossil phytolith assemblages and model/data comparisons a new tool for estimating C 3 /C 4 grass composition over time. We tested the reliability of modern soil phytolith assemblages and phytolith indices for tracing the dominance of different grass subfamilies and tree cover density. We analyzed modern soil phytolith assemblages from sites over elevation gradients on Mount Kenya (Kenya), Mount Rungwe and around Lake Masoko (southern Tanzania). These data were compared with available botanical data. A phytolith index named Ic, proved to be an effective proxy of the proportions of Pooideae, Arundinoideae and Bambusoideae grasses (mainly C 3 grasses) versus Panicoideae grasses (mainly C 4 grasses), increasing with elevation in East-Africa. When tropical mountains are covered by open habitats (e.g. grasses and shrublands), Ic should be a reliable proxy of the C 3 /C 4 grass composition. These results highlight the value of the phytolith index Ic, when interpreting paleo-environmental records from tropical mountains, to: 1) better understand past local and regional C 3 /C 4 grass distributions and associated climatic changes and 2) increase the set of C 3 /C 4 data available for model/data comparisons.

Since 1984 the Isles of Hyères have been the subject of a multi-disciplinary research programme including archaeology, geomorphology and anthracology. Comparison of the observations allow to go beyond a simple traditional inventory of archaeological sites by placing them in the context of a study of the natural environment. This work reveals the relative stability of the latter, the strictly insular characteristics of its evolution and a delay in the effects of human settlement on the environment., Les îles d'Hyères ont fait l'objet depuis 1984 d'un programme de recherche pluridisciplinaire rassemblant l'archéologie, la géomorphologie et l'anthracologie. La confrontation des observations permet d'aller au-delà du simple inventaire traditionnel de sites archéologiques, en l'insérant dans une étude du milieu naturel. Ce travail met en évidence la relative stabilité de ce dernier, les caractéristiques proprement insulaires de son évolution et un retard des effets de I'anthropisation sur l'environnement., Borréani Marc, Chabal Lucie, Mathieu Laurent, Michel Jean-Marie, Pasqualini Michel, Lippmann-Provansal Mireille. Peuplement et histoire de l'environnement sur les îles d'Hyères (Var). In: Documents d'Archéologie Méridionale, vol. 15, 1992. Espaces et monuments publics protohistoriques de Gaule méridionale. pp. 391-416.

The aim of this research was to reconstruct vegetation changes (with climate inferences) that occurred during the Holocene in the Fernando de Noronha Island, Pernambuco State, northeastern Brazil. The research approach included the use of geochemical (mineralogy, elemental), carbon isotopes (δ13C, 14C) and pollen analyses in soil organic matter (SOM) and sediments collected in Lagoa da Viração and Manguezal do Sueste. The carbon isotopes data of SOM indicated that there was no significant vegetation changes during the last 7400 BP, suggesting that the climate was not the determinant factor for the vegetation dynamics. The pollen analysis of the sediment of a core collected in the Lagoa da Viração showed the absence of Quaternary material in the period between 720 BP and 90 BP. The mineralogical analysis of deeper layer showed the presence of diopside indicating this material was developed "in situ". Only in the shallow part of the core were found pollen of similar plant species of the modern vegetation. The geochemistry and isotope results, in association with the sediment type and pollen analyses of sediment samples of Manguezal do Sueste, indicated variations in the vegetation and in its location since the middle Holocene. Such variations can be associated with climatic events and sea level oscillations and also with anthropogenic events considering the last five hundred years._________________________________________________________________________________________ RESUMO: Esta pesquisa teve o objetivo de reconstruir trocas de vegetação (com referências climáticas) que ocorreram durante o Holoceno na ilha de Fernando de Noronha, Estado de Pernambuco, nordeste do Brasil. Para o desenvolvimento da pesquisa utilizou-se de análises geoquímicas (minerais, elementar), isótopos do carbono (δ13C, 14C) e análises polínicas em solos e sedimentos coletados na Lagoa da Viração e no manguezal do Sueste. Os isótopos do carbono dos solos indicaram que não houve trocas significativas de vegetação durante os últimos 7400 anos AP, sugerindo que o clima não foi um fator determinante para a dinâmica da vegetação. A análise polínica dos sedimentos da Lagoa da Viração mostrou ausência de elementos quaternários no período entre 720 AP e 90 AP. A análise mineralógica das camadas mais profundas mostrou a presença de diopsídeo, indicando que este material foi desenvolvido"in situ". Somente na parte superficial do testemunho foram encontrados palinomorfos de plantas similares à vegetação moderna. Os resultados geoquímicos e isotópicos, em associação com o tipo de sedimento e as análises polínicas das amostras de sedimento do Manguezal do Sueste, indicaram variações na vegetação e na sua localização desde o Holoceno médio. Tais variações podem estar associadas a eventos climáticos e oscilações do nível do mar e também a eventos antrópicos considerando os últimos quinhentos anos.

The aim of this research was to reconstruct vegetation changes (with climate inferences) that occurred during the Holocene in the Fernando de Noronha Island, Pernambuco State, northeastern Brazil. The research approach included the use of geochemical (mineralogy, elemental), carbon isotopes (delta C-13, C-14) and pollen analyses in soil organic matter (SOM) and sediments collected in Lagoa da Viracao and Manguezal do Sueste. The carbon isotopes data of SOM indicated that there was no significant vegetation changes during the last 7400 BP, suggesting that the climate was not the determinant factor for the vegetation dynamics. The pollen analysis of the sediment of a core collected in the Lagoa da Viracao showed the absence of Quaternary material in the period between 720 BP and 90 BP. The mineralogical analysis of deeper layer showed the presence of diopside indicating this material was developed "in situ". Only in the shallow part of the core were found pollen of similar plant species of the modern vegetation. The geochemistry and isotope results, in association with the sediment type and pollen analyses of sediment samples of Manguezal do Sueste, indicated variations in the vegetation and in its location since the middle Holocene. Such variations can be associated with climatic events and sea level oscillations and also with anthropogenic events considering the last five hundred years.