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ABSTRACT: The impact of pre‐Columbian indigenous communities on forest cover in Amazonia is highly contentious, particularly for the wettest forests. To contribute to this debate, we studied the vegetation and fire history of a site, Quistococha, which lies within the aseasonal forests of the northern Peruvian Amazon and is associated with independently dated pre‐Columbian and recent human occupation. Paired cores from swamp and lake environments were used to distinguish landscape‐scale changes in vegetation from local‐scale succession. An increased abundance of disturbance‐adapted taxa in the pollen record from the lake, but not swamp, since c. AD 1860 probably reflects extensive deforestation related to the expansion of the nearby city of Iquitos. However, previous persistent occupation of the site by pre‐Columbian indigenous communities, indicated by the charcoal record from the lake site, is not associated with evidence for similarly extensive disturbance of the landscape. The unique features of this site therefore demonstrate that occupation by indigenous communities over thousands of years was not associated with large‐scale deforestation. These results support an emerging model of persistent but localized impacts by pre‐Columbian indigenous communities on aseasonal Amazonian forests. [ABSTRACT FROM AUTHOR]

The peatland pole forests of the Pastaza-Marañón Foreland Basin (PMFB), Peru, are the most carbon-dense ecosystems known in Amazonia once below ground carbon stores are taken into account. Here we present the first multiproxy palaeoenvironmental record including pollen data from one of these peatlands, San Jorge in northern Peru, supported by an age model based on radiocarbon and 210 Pb dating. The pollen data indicate that vegetation changes during the early phases of peat initiation resulted from autogenic succession in combination with fluvial influence. The overall pattern of vegetation change is not straightforward: the record does not reflect a process of unidirectional, progressive terrestrialization, but includes a reversal in the succession and vegetation transitions, which omit predicted successional phases. This complexity is similar to that seen in the only other existing pollen record from a PMFB peatland, at Quistococha, but contrasts with peat records from Panama and Southeast Asia where successional patterning appears more predictable. Our dating results provide the first evidence from a PMFB peatland that peat accumulation may have been discontinuous, with evidence for reduced rates of peat accumulation, or a possible hiatus, around 1300–400 cal yr BP. An ecological shift from open lake to palm swamp occurs at this time, possibly driven by climatic change. The pollen data indicate that the present pole forest vegetation at San Jorge began to assemble c. 200–150 cal yr BP. Given this young age, it is likely that the pole forest at this site remains in a state of transition. [ABSTRACT FROM AUTHOR]

The central Congo Basin contains the largest known peatland complex in the tropics. Here we present a detailed multi-proxy record from a peat core, CEN-17.4, from the centre of a 45 km wide interfluvial peatland (Ekolongouma), the first record of its kind from the central Congo peatlands. We use pollen, charcoal, sedimentological and geochemical data to reconstruct the site's history from the late Pleistocene to the present day. Peat began accumulating at the centre of the peatland ∼19,600 cal BP (∼17,500–20,400 cal BP, 95% confidence interval), and between ∼9500 (9430–9535 cal BP) and 10,500 (10,310–10,660 cal BP) cal BP towards the margins. Pollen data from the peatland centre show that an initial grass- and sedge-dominated vegetation, which burned frequently, was replaced by a Manilkara -type dominated flooded forest at ∼12,640 cal BP, replaced in turn by a more mixed swamp forest at ∼9670 cal BP. Mixed swamp forest vegetation has persisted to the present day, with variations in composition and canopy openness likely caused at least in part by changes in palaeo-precipitation. Stable isotope data (δD n-C29-v&icecorr) indicate a large reduction in precipitation beginning ∼5000 and peaking ∼2000 cal BP, associated with the near-complete mineralization of several metres of previously accumulated peat and with a transition to a drier, more heliophilic swamp forest assemblage, likely with a more open canopy. Although the peatland and associated vegetation recovered from this perturbation, the strong response to this climatic event underlines the ecosystem's sensitivity to changes in precipitation. We find no conclusive evidence for anthropogenic activity in our record; charcoal is abundant only in the Pleistocene part of the record and may reflect natural rather than anthropogenic fires. We conclude that autogenic succession and variation in the amount and seasonality of precipitation have been the most important drivers of ecological change in this peatland since the late Pleistocene. • Peat began accumulating at the centre of the interfluvial peatland ∼19,600 cal BP (∼17,500–20,400 cal BP). • Peat initiated at locations towards the margins between ∼9500 and 10,500 cal BP (according to central age estimates). • Peat initiated in a grass- and sedge-dominated floodplain environment with frequent fires. • Forest dominated by Manilkara -type established ∼12,650 cal BP, moving to a more mixed swamp forest ∼9670 cal BP. • Forest composition fluctuated over time in response to variations in wetness (precipitation amount and seasonality). [ABSTRACT FROM AUTHOR]

Abstract: We examine mid- to late Holocene centennial-scale climate variability in Ireland using proxy data from peatlands, lakes and a speleothem. A high degree of between-record variability is apparent in the proxy data and significant chronological uncertainties are present. However, tephra layers provide a robust tool for correlation and improve the chronological precision of the records. Although we can find no statistically significant coherence in the dataset as a whole, a selection of high-quality peatland water table reconstructions co-vary more than would be expected by chance alone. A locally weighted regression model with bootstrapping can be used to construct a ‘best-estimate’ palaeoclimatic reconstruction from these datasets. Visual comparison and cross-wavelet analysis of peatland water table compilations from Ireland and Northern Britain show that there are some periods of coherence between these records. Some terrestrial palaeoclimatic changes in Ireland appear to coincide with changes in the North Atlantic thermohaline circulation and solar activity. However, these relationships are inconsistent and may be obscured by chronological uncertainties. We conclude by suggesting an agenda for future Holocene climate research in Ireland. [Copyright &y& Elsevier]

To elucidate the vegetation dynamics in the Aegean region during the last 20 kyr, we have studied terrestrial palynomorphs in marine core GeoTü SL152 (Mount Athos Basin, northern Aegean Sea) at centennial-scale (125 to 300 yr) resolution. The robust chronology of the core allows us to reliably date signals of short-term vegetation change in the Aegean region. For the Pleniglacial interval until ∼14.6 kyr BP, our data document steppe vegetation, suggesting dry climatic conditions in the borderlands of the Aegean Sea. Subaerially exposed parts of the shelf were probably colonized by Pinus-dominated vegetation until shelf areas were flooded during Lateglacial sea-level rise. The final, rapid decrease of Pinus pollen percentages between ∼14 and ∼13 kyr BP appears to be connected to meltwater pulse MWP-1A. The Lateglacial interstadial complex (ie, Meiendorf, Bølling and Allerød) is characterized by the spread of oak trees, but also by the continuous presence of steppe elements, indicating only slightly increased humidity. The Younger Dryas chronozone was the driest interval of the past 20 kyr. Insufficient humidity was most likely also responsible for the ∼2.0 kyr delay in Holocene reforestation in the Aegean region relative to western Greece. During the Holocene, the vegetation was repeatedly affected by centennial-scale episodes of reduced moisture availability. Radiocarbon-based age models of previously published pollen records imply strong discrepancies in vegetation development in the Aegean region, but there are reasons to doubt the accuracy of these age models. Here we use the well-dated pollen record from marine core SL152 and biostratigraphic correlation to propose revised chronologies for several published terrestrial pollen records. This re-assessment yields a spatiotemporally consistent pattern of vegetation dynamics in the borderlands of the Aegean Sea. [ABSTRACT FROM AUTHOR]

As an isolated island group lying off the NW European mainland which was uninhabited until the mid-first millennium AD, the Faroes offer a unique opportunity to study natural processes of Holocene ecosystem development in a region where anthropogenic activity is usually a complicating factor. In this paper new radiocarbon dates and pollen-analytical data from the island of Sandoy, in the centre of the Faroes archipelago, are presented. Together with existing pollen and plant macrofossil records, these data allow a reconstruction of patterns of Holocene vegetational and edaphic change. Basal peat dates indicate that large areas of blanket mire were established long before the first human settlement, demonstrating conclusively that human impact is not necessary for the development of such ecosystems. The timing of the initiation of the blanket peats varies markedly, both across the Faroes as a whole and at a landscape scale, with dates distributed evenly over 9000 years. This suggests that, in the Faroes at least, pedogenesis was more important than climatic change in determining the timing of the spread of blanket peat systems. [ABSTRACT FROM PUBLISHER]