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Patagonian shrub and ecotonal communities were sensitive to past environmental changes and thus may also be affected by future ones. Therefore, their paleoecological study constitutes a valuable tool to understand the way in which these plant communities respond to the forcings responsible for environmental variability. The aim of this paper is to reconstruct the vegetation dynamics of the Pueyrredón Lake area (47°25′55′′ S; 72°0.7′7′′ W) for the last 3000 cal yr BP and to contextualize these changes in a regional paleoclimatic framework. The results indicate that at the beginning of the 2900 cal yr BP, the vegetation in the northwest of Santa Cruz, Argentinian Patagonia, was represented by a grass-shrub steppe associated with forest–shrub steppe ecotonal elements. This information correlates with the larger-scale environmental inferences described for the period, which indicate an increase in moisture availability due to the weakening of the westerly winds. A marked change to arid conditions is indicated in the last 1050 cal yr BP, with the establishment and development of different shrub steppe communities and the lack of ecotonal elements. Although vegetation was sensitive to changes in moisture conditions related to the variability of the westerly winds, there is evidence of differences in the composition of shrub vegetation regarding the sequences analyzed. Variations in pollen proportions of the shrub steppes in the Pueyrredón Lake area suggest that changes in vegetation are not only due to climate variability but also local factors in the areas where shrub communities grow. The integration of the information with other Patagonian sequences allowed to frame these changes in a regional context. The results obtained provide useful information to understand the way vegetation changed in the past and the manner in which it may respond to future changes. [ABSTRACT FROM AUTHOR]

Climate changes over the past two millennia in the central part of the Gulf of St. Lawrence are documented in this paper with the aim of determining and understanding the natural climate variability and the impact of anthropogenic forcing at a regional scale. The palynological content (dinocysts, pollen, and spores) of the composite marine sediment core MSM46-03 collected in the Laurentian Channel was used to reconstruct oceanographic and climatic changes with a multidecadal temporal resolution. Sea-surface conditions, including summer salinity and temperature, sea-ice cover, and primary productivity, were reconstructed from dinocyst assemblages. Results revealed a remarkable cooling trend of about 4°C after 1230 cal yr BP (720 CE) and a culmination with a cold pulse dated to 170-40 cal yr BP (1780-1910 CE), which likely corresponds to the regional signal of the Little Ice Age. This cold interval was followed by a rapid warming of about 3°C. In the pollen assemblages, the decrease of Pinus abundance over the past 1700 yr suggests changes in wind regimes, likely resulting from increased southerly incursions of cold and dry Arctic air masses into southeastern Canada. [ABSTRACT FROM AUTHOR]

The climate variability and related sea-level changes during the Holocene are still under discussion, especially in a regional context. Very little information comes from the southern and south-eastern Baltic coast. The aim of the paper is to gain insight on the history of regional environmental changes, particularly sea-level and storminess, and their driving forces. The investigations were located on a peatland on the coast of Puck Lagoon (Gulf of Gdańsk, southern Baltic Sea). The analysis of peat core comprised: radiocarbon dating, analysis of stable isotopes 18O and 13C and chemical components, as well as palynological and diatomic studies. Results showed the 1.0 m peat section accumulated over 1500 years, with a time resolution of 100 years per sample. The average water level in the Puck Lagoon rose by ca. 0.85 m during the last 1500 years in a cyclic mode, with a period cycle of ca. 600–550 years and an amplitude not exceeding 0.5 m. The accelerated sea level rise and frequent storminess occurred during the first half of the Dark Ages (1500−1300 years b2k) and LIA (750−450 years b2k) and since the beginning of the 20th century. Recognized environmental changes are well correlated with both temperature changes in the North Atlantic and changes in total solar irradiance, suggesting synchronous Northern Hemisphere-wide fluctuations. The solar forcing was an important constituent of natural climate variability in the past and of forcing climate warming during modern times - after the Little Ice Age. [ABSTRACT FROM AUTHOR]

This paper presents continuous, high resolution fossil pollen and microcharcoal records from Bo Langvlei, a lake in the Wilderness Embayment on South Africa's southern Cape coast. Spanning the past ~1300 years and encompassing the Medieval Climate Anomaly (MCA; c. AD 950–1250) and the Little Ice Age (LIA; c. AD 1300–1850), these records provide a rare southern African perspective on past temperature, moisture and vegetation change during these much debated periods of the recent geological past. Considered together with other records from the Wilderness Embayment, we conclude that conditions in the region during the MCA chronozone were – in the context of the last 1300 years – likely relatively dry (reduced levels of Afrotemperate forest pollen) and perhaps slightly cooler (increased percentages of Stoebe -type pollen) than present. The most significant phase of forest expansion, and more humid conditions, occurred during the transition between the MCA and the most prominent cooling phase of the LIA. The LIA is clearly identified at this locality as a period of cool, dry conditions between c. AD 1600 and 1850. The mechanisms driving the changes observed in the Bo Langvlei pollen record appear to be generally linked to changes in temperature, and changes in the influence of tropical circulation systems. During warmer periods, moisture availability was higher at Bo Langvlei, and rainfall was perhaps less seasonal. During colder periods, precipitation resulting from tropical disturbances was more restricted, resulting in drier conditions. While increased precipitation has been reported during the LIA from Verlorenvlei in the Western Cape as a result of an equatorward displacement of the westerly storm-track at this time, the opposing response at Bo Langvlei suggests that any increased influence of westerlies was insufficient to compensate for the concurrent reduction in tropical/local rainfall in the region. [ABSTRACT FROM AUTHOR]

The mixed semi-evergreen forests in lowland central equatorial Africa can contain many elements of secondary vegetation. This raises the question of what factors have determined the current forest composition in this region. Is this forest in the process of succession after natural climatic variation and/or anthropogenic disturbances in the past, or is it a stable forest type? This paper presents a multiproxy palaeoecological analysis of a sedimentary sequence taken from a small sedimentary basin located in logged semi-evergreen lowland forest in northern Congo-Brazzaville which addresses these questions. Analyses undertaken included fossil pollen, geochemical and microscopic charcoal. Geochemical results were interpreted as a proxy for rainfall, and showed that northern Congo has experienced changes in rainfall during the past 2580 years, while microscopic charcoal concentrations indicated increased burning from approximately 1240 cal. yr BP to the present. Analysis of the fossil pollen assemblages showed that although light-demanding taxa were a major constituent of this forest throughout the sequence, shade-tolerant taxa were more abundant in the forest prior to 1345 cal. yr BP. Increases in aridity and/or droughts after 1345 cal. yr BP, and an increase in fire after 1240 cal. yr BP resulted in a semievergreen forest with abundant pioneers that persisted with minor changes in composition during the last 900 years, even during a period of increased rainfall from 400 to 100 cal. yr BP. These data may guide conservation policy by predicting potential consequences of future climate change and the impact of logging. [ABSTRACT FROM AUTHOR]

Aim To investigate the human impact on eastern Mediterranean ecosystems in a subhumid to semi-arid region of the Near East. Location This paper considers data from Bereket (1410–1440 m a.s.l.), an intramontane basin surrounded by the Kokayanık Tepe (1830 m a.s.l.) and the Beşparmak Dağları (2280 m a.s.l.), in the western Taurus Mountains of south-west Turkey. Methods Late Holocene samples were collected along an 800-cm-deep sediment profile cored in the secondary valley of the Bereket basin. Descriptive vegetation data and modern pollen samples (moss polsters) were collected at elevational intervals of c. 15 m along an altitudinal transect from the Bereket basin (over Tepe Düzen, 1600 m a.s.l.) to Ağlasun Dağı (1700 m a.s.l.). Information about the spatial distribution of the present land cover was obtained from ASTER satellite imagery. Digital elevation-derived data and geological information were used to examine the relationship between actual land cover and other environmental variables. Results The well dated Bereket sequence provides a unique record of biennial-to-decadal landscape changes driven primarily by intensive human impact from 360 cal. yrbc to 650 cal. yrad. Since 360 cal. yrbc, over-exploitation of the land has led to altitudinal variation of tree lines, a destruction of the natural forest ecosystems ( Pinus– Quercus cerris mixed forest), and an extensive spread of forest-steppe in the highlands. The present-day distribution of vegetation in the basin area shows that human activities remain the major factor influencing the character of modern ecosystems. Main conclusions This research demonstrates the long-term local destructive effects of human impacts on the mountainous ecosystems in a small Anatolian intramontane basin since 360 cal. yrbc, and the capacity of these ecosystems to recover during periods of reduced human impact. The late Holocene history and modern vegetation characteristics show that the past and present-day distribution and composition of vegetation are influenced primarily by human activity, and that substrate, elevation, slope and orientation are of secondary significance. [ABSTRACT FROM AUTHOR]

The modern floristic composition of the principal raised bogs of Wales is significantly altered compared with their histories of development from the early to mid Holocene. This paper uses pollen and plant macrofossil records from two raised bogs together with previously published data from a further two sites to explore the key factors contributing to the present condition of Welsh ombrotrophic plant communities. Results show Betula and Molinia invasion is a recent feature of bog development in Wales. Previous Holocene ‘dry-phases’ were characterized by Ericaceae and Pinus establishment, supporting recent experimental evidence that Betula and Molinia encroachment is primarily a response to nitrogen (N) loading rather than desiccation on intact bogs. Several of the bogs featured in this study also show severe signs of structural damage, not only from peat cutting but, in the case of Cors Caron, from channel processes in the adjacent River Teifi. Radiocarbon dating and inter-site comparisons of peat accumulation rates show that Rhos Goch Common in particular has been heavily impacted by peripheral peat cutting, leading to dewatering, significant subsidence of its peat dome and the spread of hummock and high dry ridge communities. Finally, the decline and local extinction of Sphagnum austinii in bogs across Europe represents one of the most significant changes in ombrotrophic community composition in the late Holocene. Co-registered pollen and macrofossil evidence from Cors Caron demonstrates that increases in landuse intensity over the last 2000 years are temporally associated with reductions in the abundance of S. austinii and ultimately its local disappearance from the palaeoecological record. [ABSTRACT FROM AUTHOR]

In this paper, we undertake a high-resolution palynological analysis of a sediment core covering the last 1500 years obtained from Lake Ayakum in the northern Tibetan Plateau, to improve the understanding of regional climate fluctuations and their driving mechanisms. The pollen spectra are dominated by herbaceous species such as Artemisia , Chenopodiaceae, Cyperaceae and Poaceae, which grew in various alpine desert settings. Four pollen assemblage zones are identified using stratigraphically constrained cluster analysis, representing climate history at different stages. The Artemisia /Chenopodiaceae (A/C) ratio and axis score of the first principal component are used to infer regional moisture conditions and reveal a temporal pattern that is consistent with various records from central Asia. The source of Cyperaceae pollen is mainly from marsh wetlands distributed around the lake, which responded sensitively to the lake level fluctuations. In contrast, arboreal pollen is mainly a long-distance transported component, reflecting changes in regional vegetation. Our findings show that the northern Tibetan Plateau experienced relatively wet conditions during the Dark Age Cold Period and the Little Ice Age, while relatively dry conditions occurred during the Medieval Warm Period and the last two centuries. Fluctuations in moisture levels are broadly consistent with moisture records elsewhere in western China, and show a good correlation with phase changes of the North Atlantic Oscillation. The climate changes in the northern Tibetan Plateau are supposed to be primarily triggered by the NAO phases through south-north migrations of the mid-latitude westerlies during the late Holocene. • Fossil pollen based 1500-year vegetation and climate changes on the northern Tibetan Plateau. • Major pollen species were analyzed and interpreted in terms of regional moisture variations. • Four vegetation and climate stages during the late Holocene were determined accordingly. • NAO phases affected northern TP climate through south-north migrations of the westerlies. [ABSTRACT FROM AUTHOR]

This paper presents a multiproxy high-resolution study of the past 2600 years for Seebergsee, a small Swiss lake with varved sediments at the present tree-line ecotone. The laminae were identified as varves by a numerical analysis of diatom counts in the thin-sections. The hypothesis of two diatom blooms per year was corroborated by the [sup 210]Pb and [sup 137]Cs chronology. A period of intensive pasturing during the 'Little Ice Age' between AD 1346 and AD 1595 is suggested by coprophilous fungal spores, as well as by pollen indicators of grazing, by the diatom-inferred total phosphorus, by geochemistry and by documentary data. The subsequent re-oligotrophication of the lake took about 88 years, as determined by the timelag between the decline of coprophile fungal spores and the restoration of pre-eutrophic nutrient conditions. According to previous studies of latewood densities from the same region, cold summers around AD 1600 limited the pasturing at this altitude. This demonstrated the socio-economic impact of a single climatic event. However, the variance partitioning between the effects of land use and climate, which was applied for the whole core, revealed that climate independent of land use and time explained only 1.32% of the diatom data, while land use independent of climate and time explained 15.7%. Clearly land use influenced the lake, but land use was not always driven by climate. Other factors beside climate, such as politics or the introduction of fertilizers in the seventeenth and eighteenth centuries also influenced the development of Alpine pasturing. [ABSTRACT FROM AUTHOR]

High‐quality records of hydroclimate variability in central Mexico during the last 2000 years are necessary to better understand human–environment interactions in Mesoamerica. Of particular interest are the climatic conditions during the Epiclassic period (ad 600–900), as droughts have been associated with a cultural demise occurring around ad 900–1000. We reconstruct the hydroclimate history of the last 2000 years based on a sediment record from a drought‐sensitive lake located near one of the most important Epiclassic city‐states in Mesoamerica. Titanium concentrations, pollen and diatoms give a consistent environmental signal of five droughts occurring at about: (i) ad 50–250, (ii) ad 700–950, (iii) ad 1200–1300, (iv) ad 1450–1550 and (v) ad 1760–1820. Some droughts were associated with cooler climatic conditions, and all of them framed major historical events. Our results show that the great cultural development of the Epiclassic period (ad 600–900) was framed by a scenario of drought conditions followed by abandonment at ad 900–1000. A brief return to moister conditions is recorded before another drought during the time of the fall of the city‐state of Tula (1200). European contact (1521) and the War of Independence (1810–20) also occurred during times of drought. [ABSTRACT FROM AUTHOR]

The Late Holocene fossil pollen records from the Zemu glacier, located in Yabuk, North Sikkim, in the eastern Himalayas, effectively generated quantitative climate reconstructions based on the transfer function model. The transfer function model was developed by establishing a modern pollen–climate calibration set from the temperate alpine belt of North Sikkim. A redundancy analysis was carried out to detect the pattern of variation of climatic variables in the modern pollen datasets. The mean annual precipitation (MAP) and mean temperature of the warming month (MTWA) had the strongest influence on the composition of the modern pollen samples among the climatic variables considered in the analysis. Proxy data in the form of fossil pollen records were analyzed for reconstructing past climate based upon the relationships between modern pollen vegetation assemblages and climatic patterns. Transfer functions for MAP and MTWA were developed with the partial least squares (PLS) approach, and model performance was assessed using leave-one-out cross-validation. The validated model was used to reconstruct MAP and MTWA for the last 2992 cal years BP (1042 BC) in North Sikkim. The variability observed in the reconstructions was analyzed for past global climatic events. It was further compared with the available regional and hemispheric proxy-based climate reconstructions. The reconstructions captured comparable Medieval Warm Period (MWP) and Little Ice Age (LIA)-like events from the Zemu glacier region. The fossil pollen data and climate reconstructions were further compared with the mineral magnetism data of the subsurface sediment profile. [ABSTRACT FROM AUTHOR]

Fossil pollen and spore diversity in marine sediment cores from the coasts off SW Kalimantan and NE Java (Java Sea) as well as modern pollen assemblages collected off West Java in the SE Indian Ocean in a marine sediment trap are documented in this paper. In total, photographic images of 138 pollen and 41 spores including 14 pollen and 32 unidentified spore types are presented in morphological order. Illustrated pollen and spore taxa list may help pollen and spore identification of future palynological investigations focused on the reconstruction of past vegetation, climate and environment dynamics in SE Asia. [ABSTRACT FROM AUTHOR]

This paper presents a new palynological record from a 146 cm long finely laminated sediment core obtained in 2009 from the deep-water meromictic Lake Shira (54°30′38″N, 90°12″09′E; ca. 353 m a.s.l.) situated in the Khakassian steppe region of southern Siberia between the rivers Ob' and Yenisei. The area is rich in lakes and represents an exceptionally well preserved sequence of Bronze and Iron Age archeological cultures. Little is known about the changes in vegetation and climate of the region during the Holocene. The palynological analysis of the core allows us to partly fill up this gap in current knowledge. The record of pollen and non-pollen palynomorphs presented here covers the past 2450 year interval with an average resolution of 22 years. The results obtained support the interpretation that the late Holocene vegetation changes around Lake Shira are mainly associated with large-scale atmospheric circulation processes controlling the regional water balance rather than with human activities. An attempt to trace human impact in the pollen assemblages provides no clear evidence for anthropogenic activity, except for the last few decades since ca. 1955, though the region has a long history of mobile pastoralists. For explanation of decadal-scale changes in the regional vegetation cover, the Artemisia /Chenopodiaceae (A/C) pollen ratio proved to be a reliable indicator of effective moisture availability. Using available fossil and published instrumental data our study suggests a link between the North Atlantic warmer/colder temperatures and higher/lower atmospheric precipitation (or moisture availability) in southern Siberia at multi-decadal to centennial scales. [ABSTRACT FROM AUTHOR]

Pollen records and radiocarbon dates from cultivation layers were compiled to explore agricultural changes in southwestern Norway, with a focus on cereals and associated herbs. Variations in the pollen composition were examined using rarefaction and multivariate analyses. The results showed that prehistoric cultivation layers were preserved in the region from c. 2200 BC to AD 1400. That the landscape was open and dominated by grassland is inferred from the preponderance of grass and other herbaceous pollen, originating from meadows and pastures. A few annual weeds were associated with cereals, such as Spergula arvensis and Polygonum persicaria. The main change in our record occurred during the Early Iron Age (c. 500 BC-AD 600), when cultivated fields and grassland expanded at the expense of woodland, and was probably associated with the establishment of permanent fields and hay-meadows. This study shows that pollen analysed from cultivation layers can be synthesised to provide a regional picture of land-use development. [ABSTRACT FROM AUTHOR]

Pollen analyses of a 90 cm deep lacustrine sediment profile from the Mahasamund District of Chhattisgarh State, central India demonstrated that between ca. 3600 and 2500 cal yr BP (Neoglacial climate interval), open forest vegetation occupied the landscape in the region under a dry climate, probably indicating reduced monsoon (the Indian Summer Monsoon: ISM) rainfall. Further, the open forest vegetation was succeeded by a mixed tropical deciduous forest between ca. 2500 and 1650 cal yr BP (∼550 BC to AD ∼300) under a warm and humid climate with increased monsoon rainfall. The warming period and an amelioration of climate (strong ISM condition) is comparable to the Roman Warm Period (RWP), recorded globally between 2500–1600 cal yr BP (∼550 BC to AD ∼350), and also known as the 'Golden Age of India' owing to increased agricultural output, trade commerce and socio-economic prosperity in India. Subsequently, between ca. 1650 and 950 cal yr BP (AD ∼300–1000), the existing mixed tropical deciduous forest transformed into an open mixed tropical deciduous forest under a warm and relatively less humid climate with reduced monsoon rainfall, correlatable with the Dark Ages Cold Period (DACP). Finally, between ca. 950 cal yr BP to the present (AD 1000 onwards), mixed tropical deciduous forest again came into existence and occupied the landscape around the study area under a warm and relatively more humid climate with intensification of the monsoon rainfall, corresponds with the Medieval Warm Period (MWP), which is known between AD 740 and 1150 worldwide. [ABSTRACT FROM AUTHOR]

Two lake-sediment cores from the western and central Canadian Arctic were used to investigate late Holocene climate variability in the region. Both cores were analyzed for pollen, organic matter, biogenic silica, and magnetic susceptibility, and were dated using a combination of Pb and C techniques. Core MB01, from southwestern Victoria Island, provides a 2600-year-long record. Fossil pollen percentages, along with other parameters, suggest the occurrence of a cold period around 2400 cal year BP (450 BC), followed by slightly warmer conditions by 1800 cal year BP (150 AD), and a return to cooler conditions throughout much of the last millennium. Core SL06, from southern Boothia Peninsula, shows more subtle changes in pollen percentages over its 2500-year duration, but an increase in Cyperaceae and decrease in Oxyria pollen around 1400 cal year BP (550 AD) are indicative of warmer conditions at that time. Quantitative climate reconstructions from these pollen sequences were compared to two other pollen-based climate records from the region and indicate the presence of a widespread wet period ~1500 cal year BP (450 AD), and a cool and dry Little Ice Age. In the reconstructions based on pollen percentage data, the twentieth century summer temperature and annual precipitation in the central and western Canadian Arctic were comparable to that which occurred over the last 2500 years. However, pollen-influx values increase in the most recent sediments, suggesting high plant productivity during the late twentieth century. [ABSTRACT FROM AUTHOR]

Patagonian shrub and ecotonal communities were sensitive to past environmental changes and thus may also be affected by future ones. Therefore, their paleoecological study constitutes a valuable tool to understand the way in which these plant communities respond to the forcings responsible for environmental variability. The aim of this paper is to reconstruct the vegetation dynamics of the Pueyrredón Lake area (47°25′55′′ S; 72°0.7′7′′ W) for the last 3000 cal yr BP and to contextualize these changes in a regional paleoclimatic framework. The results indicate that at the beginning of the 2900 cal yr BP, the vegetation in the northwest of Santa Cruz, Argentinian Patagonia, was represented by a grass-shrub steppe associated with forest–shrub steppe ecotonal elements. This information correlates with the larger-scale environmental inferences described for the period, which indicate an increase in moisture availability due to the weakening of the westerly winds. A marked change to arid conditions is indicated in the last 1050 cal yr BP, with the establishment and development of different shrub steppe communities and the lack of ecotonal elements. Although vegetation was sensitive to changes in moisture conditions related to the variability of the westerly winds, there is evidence of differences in the composition of shrub vegetation regarding the sequences analyzed. Variations in pollen proportions of the shrub steppes in the Pueyrredón Lake area suggest that changes in vegetation are not only due to climate variability but also local factors in the areas where shrub communities grow. The integration of the information with other Patagonian sequences allowed to frame these changes in a regional context. The results obtained provide useful information to understand the way vegetation changed in the past and the manner in which it may respond to future changes.

Palynological analysis and radiocarbon dating of a short sediment core from a high-altitude mire in the Arasbaran area of northwestern Iran reveals long-term vegetation dynamics, climate change and anthropogenic impact. Our findings indicate the prevalence of semi-desert steppe vegetation, with a variety of Asteraceae – mainly Lactuceae – species from 3000 to 1440 cal yr BP. This period is followed by a higher occurrence of Artemisia spp. and Brassicaceae (1440–1330 cal yr BP), a re-expansion of Lactuceae (1330–1030 cal yr BP) and Brassicaceae (1030–330 cal yr BP) and, finally, Caryophyllaceae species (since 330 cal yr BP). The reconstructed millennia-long dry climate in the highlands of northwestern Iran is in good accordance with climate reconstructions from other east Mediterranean sites. Two phases of moister conditions between 2100–1400 and 1000–350 cal yr BP would correspond to altitudinal Quercus–Carpinus forest expansion in the Arasbaran area. The earliest indication of anthropogenic activity in the area dates back to the onset of the record, around 3000 cal yr BP. The occurrence of small maxima of Juglans regia, Corylus avellana and Cornus mas pollen at around 1350 cal yr BP is interpreted to reflect a temporary expansion of fruit cultivation. For the last millennium the occurrence of pollen attributable to Polygonum, Euphorbia, Plantago and Rumex suggests a diversification of steppe vegetation, which may reflect intensified agropastoral activities in the Arasbaran highlands. Based on our pollen record, the regional vegetation in the Kalan area remained largely stable over the last three millennia. However, changes in local hydrology caused substantial changes in wetland vegetation. [ABSTRACT FROM AUTHOR]

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The history and continuity of lowland woodlands in Central Europe is closely connected with human activities. We studied a small wetland situated directly in a low-elevation oak-dominated woodland to evaluate the history and impact of humans on an oak woodland in south-eastern Slovakia. We used different proxies to obtain evidence of woodland history spanning at least 8,500 years. Pollen, diatom and physical analysis, including micromorphology, were used to study infill sediments and to determine the processes causing the influx of material into the wetland basin from its surroundings. The oak-dominated woodland community occurred throughout the Holocene, but its detailed history is impossible to trace because of reverse chronology caused by mixing of deposits. The stability of the oak woodland was determined by anthropogenic disturbances such as grazing. These disturbances are indicated by pollen taxa, signals of soil erosion in the deposits, and local development of the wetland that acted as drinking and hemp retting basin. The recent decline of human pressure has led to gradual changes in the species composition of the wetland itself (shrub encroachment) and of understory of the surrounding oak woodlands. [ABSTRACT FROM AUTHOR]

The aim of the study was to identify changes in agricultural practices and periods of agricultural expansion and regression during the last 1,300 years in the South-Swedish Uplands. Sediments from the small lake of Skärpingsgölen (1.2 ha) were used to quantify land-cover at a local scale (c. 1 km radius) in 50-year intervals based on pollen analysis and the LOVE model (Local Vegetation Estimates). The results showed a dramatic change in land-cover, starting c. ad 1150, from a grazed, deciduous woodland, dominated by Corylus, Betula and Quercus, to a semi-open landscape dominated by Picea and open agricultural land. A hamlet, situated next to the lake, was probably established during the 12th century, abandoned during the late medieval crisis (late 14th century) and re-colonized during the 16th century. High values of Cannabis-type pollen (up to 10% of the pollen sum) suggest that hemp retting was carried out in the lake from the 13th to the 17th centuries, while elevated levels of microscopic charcoal indicate that slash-and-burn cultivation was practiced during the early 14th and the 16th–18th centuries. The LRA-based estimates of vegetation show that the modern landscape, dominated by managed coniferous woodlands, is very different from the landscape only 50–100 years ago. This type of study is useful for comparisons with historical and archaeological records, and provides sufficient temporal and spatial resolution to identify short-lived abandonments and shifts in agricultural practices. [ABSTRACT FROM AUTHOR]

Today, the East European forest-steppe is an agricultural landscape with very few remains of its former natural vegetation. The history of the transformation from natural vegetation to a human-made landscape in the area of Sudzha (Kursk region, Russia) is studied here. We compare the off-site pollen record Sudzha with three on-site pollen records obtained from the archaeological site Kurilovka-2. The sediment core Sudzha covering the last 2,500 years was taken from an oxbow lake in an area with archaeological sites of the early Slavonic period (3rd–8th centuries ce). The Sudzha pollen record indicates dominance of broadleaf forests and meadow steppes in the area from 2,500 to 200 cal year bp with two major settlement phases one between ~ 2,000 and 1,600 cal year bp (~ 50 bce to 350 ce) and the other between 1,100 and 600 cal year bp (850 and 1350 ce) followed by a total deforestation and transformation to an agricultural landscape over the last 200–300 years. Similar changes in the last 300–400 years are indicated by the three on-site pollen records. It is noteworthy, however, that the record Sudzha does not provide an intensive signal of human impact during the 5th–8th centuries ce. This points to a quite restricted spatial influence of the Early Slavonic settlements on the vegetation, leading to a relatively low contribution of palynological anthropogenic indicators to the regional pollen rain signal. [ABSTRACT FROM AUTHOR]

In this study, late Holocene vegetation, climate and human impacts were investigated using multiproxy data-pollen percentages, pollen accumulation rates (PAR), humification and loss-on-ignition (LOI)-measured from peat sediments from Daiyun Mountain, southeast China. A stratigraphic chronology was established on the basis of four radiocarbon dates. The 4,350 year sequence of vegetation history and climate change exhibits three distinctive stages: (1) 4,350-1,000 cal bp, during which the vegetation was dominated by evergreen forests mainly composed of broad-leaf trees, indicating a warm and wet climate; (2) 1,000-550 cal bp, during which the climate was thought to be cool and dry, based on a decrease in pollen percentages and the PARs of trees, shrubs and wetland herbs, and an increase in the pollen percentage and PAR of dry land herbs, as well as high overall LOI values; and (3) 550 cal bp to modern times, during which higher pollen percentages of dry land and wetland herbs, along with low pollen percentage and PAR of trees and shrubs, as well as low absorbance and LOI values, suggest relatively cooler but wetter climate conditions. In addition, major climatic events, such as the warm period from ad 670-960, the Medieval Warm Period ( ad 1050-1520) and the Little Ice Age ( ad 1580-1850), could be identified within the peat sediments in this study, with climatic conditions at these times being characteristically warm and wet, warm and dry, and cold and wet, respectively. Pollen signals indicate significant human impact since 1,000 cal bp, which may be linked to the development of the local porcelain industry and a rapid increase in the population in the study region. [ABSTRACT FROM AUTHOR]

Central Chile is heavily exploited for mineral and water resources, with agriculture and large urban populations all creating intensive landscape use. Few records of past environmental and climate change are available that afford a broader context. To aid in this assessment, we present a 700-year reconstruction from Laguna del Maule (LdM) in the high Andes of central Chile based on sedimentological, geochemical, diatom and pollen analyses. The age model is based on 210Pb/137Cs and 14C dating tied into known volcanic eruptions. Sedimentology consists of organic-rich sediments and diatom oozes with several interspersed volcanic-rich facies and two tephra deposits. Sediment geochemistry exhibits increased productivity (high Br/Ti, biosilica) and more dominant oxic conditions (high Fe/Mn) from AD 1300 to 1400 and from AD 1650 to 1850, likely during periods of relatively lower lake levels and better development of littoral environments. However, during this later period, high elevation vegetation was dominant, indicative of regional cooler/wetter conditions. In contrast, sediments deposited from AD 1850 to 1930 evidence decreased productivity and increased anoxic lake bottom conditions. The ‘Little Ice Age’ (LIA) in LdM is characterized by significant variations in lake dynamics and hydrology with cooler/wetter conditions (AD 1570–1700), major environmental changes in the 18th century and ending at ca. AD 1850. LdM record documents the impact of the LIA in the southern hemisphere and stresses the global nature of this climate period. Large changes in lake dynamics and diatoms assemblages during the 20th century could be related to anthropogenic impacts, but recent changes in climate patterns cannot be excluded. [ABSTRACT FROM AUTHOR]

Climate change and human activities interact to affect the vegetation landscape. We examined the interaction of these drivers using multiproxy records, including data on pollen, charcoal, phytoliths, total nitrogen, total organic carbon, and loss-on-ignition, from a 268-cm sediment profile in Xinjiang, China. By combining these data with information gained from 214 samples of surface pollen assemblages in north Xinjiang, we were able to reconstruct the late Holocene climate using a weighted averaging partial least squares regression model. Our results suggested that the typical desert vegetation of the region changed to Artemisia desert at 2400 cal. a BP, and returned to desert after 900 cal. a BP. A warm–dry and cold–humid climate pattern existed during the past 4000 years. The climate was characterized by obvious fluctuation prior to 2400 cal. a BP, after which it became wetter and colder with little fluctuation. The temperature maximum in our reconstruction occurred around 700 cal. a BP. The macrocharcoal particles reached their highest levels at c. 3500 cal. a BP, and again at 700 cal. a BP, suggesting increases in human activities at these times. An increased amount of anthropogenic plant pollen also appeared in sediment over the past 50 years. Large numbers of Thelypteris spores and Phragmites phytoliths in the surface pollen samples from modern desert vegetation also reflect recent human activities. Therefore, our data provide evidence that both climate and human activities are important drivers of changes in regional vegetation. [ABSTRACT FROM PUBLISHER]

A pollen diagram from Lac Brulé in southwestern Québec (45°43′09″N, 75°26′32″W, 270 m) provides a late Holocene history of the vegetation. The presence of varved sediments permitted the development of a high-resolution (10-year), cross-dated chronology with an estimated error of approximately 1%. During the last 1400 years, the forests were dominated by Tsuga, Fagus, Betula, Acer and Pinus. A peak in microcharcoal and evidence of post-fire succession suggest that the changes in the pollen assemblages around ad 1375 were a consequence of a fire in the region. There was a decrease in pollen influx of several deciduous taxa and Tsuga between ad 1600 and 1700, suggesting a rapid climate change that was significant enough to have affected pollen production of these taxa. This change, associated with the beginning of the ‘Little Ice Age’ in the region, affected the forest composition for the subsequent centuries. A detailed comparison of this pollen record with that from a nearby pollen diagram also prepared at high-temporal resolution shows the ability of pollen records to record short-period climate variations and disturbances. [ABSTRACT FROM PUBLISHER]

Pollen and charcoal records of a 150 cm long lake sediment core from Taibai Lake in the middle reach of the Yangtze River reveal seven major changes in regional vegetation over the last 1500 years. During the period c. ad 480–710, evergreen broadleaved forest dominated by Castanopsis/Lithocarpus and evergreen oaks occurred in the Taibai Lake catchment. From c. ad 710 to 1050, the vegetation shifted to a mixed conifer and broadleaved forest, with Pinus expanding at the expense of Castanopsis/Lithocarpus. Between c. ad 1050 and 1320, evergreen broadleaved forest reoccupied the studied area. From c. ad 1320 to 1650, the area of primary forest decreased markedly with synchronous reduction in broadleaved trees and Pinus. Between c. ad 1650 and 1740, the biomass declined rapidly, while secondary Pinus forest began to expand. During c. ad 1740–1950, forest extent increased slightly compared with the previous stage, but the landscape was still secondary forest with the minimum proportion of broadleaved trees. After c. ad 1950, the biomass in the surrounding area was very low, with vegetation types similar to that at present (secondary Pinus forest and mixed conifer and broadleaved forest). A detrended correspondence analysis (DCA) with 125 samples and 34 main pollen types is used to separate human and climatic impacts on vegetation. Then, the pollen assemblage, DCA, charcoal record, and magnetic susceptibility are combined to discuss the key factors inducing these vegetation changes. The vegetation changes were mainly controlled by the climatic changes, with the weak impacts of human activities before c. ad 1320. Since then, the intensity of human influences on vegetation increased gradually, entering a transitional period of main controlling factors of vegetation changes from nature to human activities. After c. ad 1740, the vegetation changes were chiefly controlled by human activities, and the climatic signal was weak. [ABSTRACT FROM AUTHOR]

The impact of short-term climate anomalies and disturbances on past plant communities can be understood using high temporal or contiguous sedimentary pollen analysis. The response of pollen assemblages to decadal- to multidecadal-scale moisture variability was analyzed for the time intervals 3000-2200 and 1400-500 cal. yr BP. The hydroclimate and vegetation history for Minden Bog in southeastern Michigan were reconstructed using analyses of sedimentary testate amoebae and pollen. Results indicated that moisture anomalies accounted for 3% to 24% of the variation in arboreal pollen abundance for Fagus, Pinus, Quercus, and Tsuga. Betula pollen percentages did not appear to be affected by moisture variability. Given the longevity of these taxa, rapid arboreal pollen assemblage responses to moisture variability at decadal to multidecadal timescales were likely due to climate-induced changes in pollen productivity. Our data suggest that pollen-climate relationships may be counterintuitive at these fine temporal scales. For example, Tsuga pollen percentages generally increased during short-term dry events, in contrast to expected decreases in abundance with drying at millennial timescales based on empirical pollen-climate relationships. Results suggest caution should be used when inferring subdecadal to multidecadal climate variation from highly resolved pollen records. Rather, high-resolution pollen data may more accurately represent superimposed plant responses that are the composite of reproductive output nested within long-term plant community compositional changes in response to climatic variation. [ABSTRACT FROM AUTHOR]

This study uses palynologic data to determine the effects of regional climate variability and human activity on the formation and development of tree islands during the last ~4000 years. Although prolonged periods of aridity have been invoked as one mechanism for their formation, Native American land use has also been hypothesized as a driver of tree island development. Using pollen assemblages from head and near tail sediments collected on two tree islands and documented archeological data, the relative roles of Native Americans, climate variability, and recent water-management practices in forming and structuring Everglades tree islands are examined. The timing of changes recorded in the pollen record indicates that tree islands developed from sawgrass marshes ~3800 cal. yr BP, prior to human occupation. Major tree island expansion, recorded near tail sediments, occurred ~1000 years after initial tree island formation. Comparison of the timing of pollen assemblages with other proxy records indicates that tree island expansion is related to regional and global aridity correlated with southward migration of the Intertropical Convergence Zone. Local fire associated with droughts may also have influenced tree island expansion. This work suggests that Native American occupation did not significantly influence tree island formation and that the most important factors governing tree island expansion are extreme hydrologic events due to droughts and intense twentieth century water management. [ABSTRACT FROM PUBLISHER]

The late Holocene environmental history of two karstic uplands in the Burren, western Ireland is reconstructed. The palaeoecological investigations focus on species-rich, upland plant communities of high biogeographic interest that include Sesleria-dominated grasslands and heath communities with Dryas octopetala, Arctostaphylos uva-ursi and Empetrum nigrum. Short monoliths taken from shallow peats were pollen analytically investigated. Particular attention was paid to non-pollen palynomorphs, and especially coprophilous fungal spores as indicators of environmental change and pastoral activity at local level. The exposed north-west Burren uplands carried Pinus sylvestris-dominated woodland during the mid and late Bronze Age. The demise of pine on these uplands at ca. 600 B.C. is ascribed to human impact. Evidence is presented for increased pastoral activity in the uplands from early medieval times (ca. sixth century A.D.) onwards. Farming, involving intensive grazing of the uplands, attained greatest intensity during the late 18th and early 19th century, and resulted in more or less total clearance of Corylus scrub which, prior to that, was common in both the upland and lowland Burren. The potential of non-pollen palynomorphs and especially the coprophilous fungal spore record for elucidating traditional Burren farming practices, including winterage (a type of transhumance), is highlighted. [ABSTRACT FROM AUTHOR]

Apeat profile from a small raised bog, situated in SW Sweden, was studied for insect, pollen and charcoal analyses in order to reconstruct the late-Holocene forest history of the area. The palaeoecological records cover the last 3700 cal. years. The results were compared with archaeological data, historical documents and palaeoclimate reconstructions from the region. From 1650 cal. yr BC to AD 1310 cal. yr, the study area was characterized by deciduous woodland with a diverse invertebrate fauna. The recorded insects indicate a relatively open or mosaic forest environment with abundance of dead wood. This forest environment was probably maintained by disturbances such as cattle grazing, fire, wood coppicing and small-scale cultivation. At around AD 1310, a major and rapid change in the forest ecosystem occurred, ie, species-rich deciduous woodland was replaced by a species-poor beech forest. The data indicate that a change in land use was the likely reason for the shift in forest type. Grazing and fire ceased, while tree cutting increased. The shift in land use correlates well with political-societal changes in the region during Mediaeval time. Climate changes seem to have influenced the wetland environment, but there is no obvious correlation between major or minor shifts in forest ecosystem and reconstructed climate changes. Today, nature conservationists regard the beech forests of Halland as remains of primeval forests hosting a unique flora and fauna. Our results give new insights and challenge that view. [ABSTRACT FROM AUTHOR]

A lake-level record for the late Holocene at Lake Ledro (Trentino, northeastern Italy) is presented. It is based on the sediment and pollen analysis of a 1.75 m high stratigraphic section observed on the southern shore (site Ledro I) and a 3.2 m long sediment core taken from a littoral mire on the southeastern shore (site Ledro II). The chronology is derived from 15 radiocarbon dates and pollen stratigraphy. The late-Holocene composite record established from these two sediment sequences gives evidence of centennial-scale fluctuations with highstands at c. 3400, 2600, 1700, 1200 and 400 cal. BP, in agreement with various palaeohydrological records established in central and northern Italy, as well as north of theAlps. In addition, high lake-level conditions at c. 2000 cal. BP may be the equivalent of stronger river discharge observed at the same time in Central Italy's rivers. In agreement with the lake-level record of Accesa (Tuscany), the Ledro record also suggests a relatively complex palaeohydrological pattern for the period around 4000 cal. BP. On a millennial scale, sediment hiatuses observed in the lower part of the Ledro I sediment sequence indicate that, except for a highstand occurring just after 7500 cal. BP, lower lake levels generally prevailed rather before c. 4000 cal. BP than afterwards. Finally, the lake-level data obtained at Lake Ledro indicate that the relative continuity of settlements in humid areas of northern Italy during the Bronze Age (in contrast to their general abandonment north of the Alps between c. 3450 and 3150 cal. BP), does not reflect different regional patterns of climatic and palaeohydrological conditions. In contrast, the rise in lake level dated to c. 3400 cal. BP at Ledro appears to coincide with a worldwide climate reversal, observed in both the hemispheres, while palaeoenvironmental and archaeological data collected at Lake Ledro may suggest, as a working hypothesis, a relative emancipation of protohistoric societies from climatic conditions. [ABSTRACT FROM AUTHOR]

A series of monoliths collected from Ambra Crater in the Upper Wahgi valley, Papua New Guinea have been subject to multiproxy (pollen, microcharcoal and diatom) palaeoecological investigation. The palaeoecological record enables a relatively high-resolution reconstruction from c. 4000-500 cal. BP. Throughout the sequence, the valley floor and crater area were continuously deforested and carpeted with a grassland-disturbance taxa mosaic. Vegetation communities in the valley were largely unaffected by successive tephra deposition events, although some muted effects occurred. Tephra deposition did have considerable local effects on soil water conditions and hydrology in the base of the crater. The Ambra Crater record is consistent with longer chronologies from wetlands in the Upper Wahgi valley, which document extensive disturbance to dryland forests and their replacement with grasses and other disturbance taxa from the mid Holocene. The Ambra Crater record, taken in conjunction with previously published multisite data, enables critique and discrimination of different interpretations of agricultural history in the highlands during the late Holocene. [ABSTRACT FROM AUTHOR]

Coupled multiproxy indicators (pollen, stable isotopes and charcoal) reconstructed from annually laminated lake sediments from Nar Gölü in Cappadocia (central Turkey) complemented by documentary and archaeological evidence provide a detailed record of environmental changes and their causes from late Antiquity (AD 300) to the present day. Stable isotope data indicate marked shifts in the variability in summer drought intensity and winter-spring rainfall, but these did not coincide in time with changes in vegetation and land use shown by pollen data. Rather, human impacts appear to have been the main driver of landscape ecological changes in Cappadocia over the last two millennia. Pollen and charcoal data indicate four principal landuse phases: (i) an early Byzantine agrarian landscape characterized by cereals and tree crops, and marking the later part of the so-called Beyşehir Occupation phase; (ii) a period of landscape abandonment and the establishment of secondary woodland from AD 670 to 950 coinciding with the Arab invasions of Anatolia and marking the transition from late Antiquity to the middle Byzantine period; (iii) the re-establishment of cereal-based agriculture and pastoralism from c. AD 950, with this cultural landscape being maintained through the Byzantine 'Golden Age', the Seljuk and Ottoman Empires; and (iv) agricultural intensification during the late Ottoman era and the Turkish Republic (AD 1830 to present). Charcoal fluxes indicate that prior to the twentieth century, landscape burning was most frequent at times of diminished human impact when fuel biomass increased. Pollen and historical data show remarkably close agreement in terms of the timing of landscape change, and the former suggest that rural cultural traditions were able to survive largely intact through short-lived periods of sociopolitical dislocation such as the sixth century Justinian plague and the thirteenth century Mongol invasions. [ABSTRACT FROM AUTHOR]

The decline of S. austinii Sull. Ex Aust. (formerly S. imbricatum Hornsch. Ex Russ. ssp. austinii Sull. Ex Aust.), in most cases to local extinction, represents one of the most striking vegetation changes on the raised bogs of Britain and Northwest Europe during the last 2000 years. This study uses plant macrofossil, pollen and geochemical analyses to explore the record of human impact and land-use intensification at the S. austinii decline. There is a clear temporal association between anthropogenic woodland clearance, cereal cultivation, soil erosion and contemporary climatic change, with the decline of S. austinii. These findings suggest that S. austinii is sensitive not only to rapid climate changes but also to the aerial deposition of soil dust and/or accompanying pollutants. A modern comparison of atmospherically derived nitrogen (N) loadings with the present presence/absence of S. austinii on 16 raised bogs shows that the species is only present where the loading lies below a critical threshold for N of 10 kg/ha per yr. The palaeoecological record also shows that S. austinii has re-established itself during phases of reduced human activity but in contemporary Europe it is difficult to see this happening in the near future. [ABSTRACT FROM AUTHOR]

A high-resolution plant macrofossil analysis was applied to investigate wetness dynamics in a southern Finnish boreal bog, Kontolanrahka, during the last 5000 years. The chronological control and the age-depth model were based on 40 AMS radiocarbon dates. Pollen analysis provided information on regional-scale vegetation changes. Macrofossil analysis revealed prominent changes in vegetation assemblages during the late Holocene, indicating fluctuations in water-table. The reconstruction suggests that at the coring point, which nowadays is a relatively wet lawn, habitat type has repeatedly varied between transient communities similar to those currently represented in dry hummocks, very wet lawns and even hollows. In order to quantify historical changes in water-table, Generalized Additive Models (GAM) were used to investigate the current relationships between surface plant species and water-table depth. Modern water-table measurements and a survey of associated plant communities along moisture gradients provided data for GAM-analyses. The plant species showed unimodal distributions with apparent optima and narrow tolerances along the water-table gradient. A transfer function for water-table reconstruction was created by calibrating plant macrofossil records against the modern vegetation/water-table relationship using the weighted averaging partial least squares (WA-PLS) regression method. The quantitative water-table reconstruction for the late Holocene showed that the water-table depth had varied between 38 and 2.5 cm, the root mean square error of prediction being 3 cm. The detected historical wet and dry shifts were compared with other similar data from Finland, Sweden and Estonia, and from Western Europe. Despite some similarities, especially during the last c. 1000 years, noticeable differences in timing and duration occur, suggesting they may not have been driven only by climate, but also by local factors, including surface fires. [ABSTRACT FROM AUTHOR]

The northern slopes of central Tianshan Mountains in Xinjiang, northwestern China can provide an ideal database to research palaeoclimate as disturbance by human impact is relatively low and the vegetation zones reflect climatic gradients. In order to establish the correlation between modern climatic factors and surface pollen assemblages and to reconstruct palaeoclimate on the northern slope of central Tianshan Mountains, three Holocene sections in Daxigou, Huashuwozi and Sichanghu located at different elevations and vegetation zones were chosen for study. A total of 80 surface pollen samples in 86 vegetation quadrats were collected for pollen-vegetation relationship analysis. The Warmth Index (WI) and Moisture Index (MI) were calculated based on averaged modern climate data during 1951 - 2000 at eight weather stations in the study area. Pollen percentages of Picea, Artemisia, Chenopodiaceae, Ephedra, and Tamarix, as well as A/C (Artemisia/Chenopodiaceae) and AP/NAP (arboreal/nonarboreal pollen) ratio were selected as pollen variables and WI and MI were chosen as climatic variables. The relationship between pollen percentages (Picea, Artemisia, Chenopodiaceae and Tamarix), A/C, AP/NAP ratio, WI and MI values were estimated (95% confidence interval) using stepwise multiple linear regression analysis. WI and MI values for the three sections were calculated using these regression equations, and palaeoclimate for the study area could be reconstructed. The results showed periods of both cool-humid and warm-dry conditions on the northern slopes of Tianshan Mountain during the late Holocene. [ABSTRACT FROM AUTHOR]

Pollen, loss on ignition and magnetic susceptibility analyses provide a high-resolution palaeoenvironmental record from Lago Puerto Arturo, Peten, Guatemala. The presence of Zea pollen ∼2650 BC provides a latest date for the arrival of maize agriculture to the region. The following 3600 years are marked by significant opening of the forest and episodic pulses of erosion. During the early Preclassic, around 1450 BC, all proxies indicate an abrupt increase in human activity, coincident with archaeological evidence of early settlement. Three discrete periods of decreased human activity are indicated by cessations of landscape disturbance. Such decreased human activity likely reflects periodic local population decline. These events coincide with times of cultural transition in the Maya lowlands and correspond to the terminal phases of the middle Preclassic, late Preclassic and late Classic periods. There is no evidence for human activity in the area following the late Classic abandonment. [ABSTRACT FROM AUTHOR]

Rice (Oryza sp.) agriculture sustains vast numbers of people and, despite great advancements made in recent years, questions about its origins and spread throughout Asia remain unanswered. This study uses sedimentary biomarker, stable carbon isotope and palynological analyses to investigate early rice agriculture in the Yangtze delta, a region where rice agriculture emerged at least 7000 years ago. Accelerator mass spectrometer (AMS) 14C dating reveals the age of sedimentary section to be between c. 6000 and 1800 cal. BP. Widespread clearing of forest vegetation c. 2400 cal. BP, is the earliest major human influence detected in the Qingpu record. Following this, rice agriculture probably dominated the Qingpu area. Evidence supporting rice agriculture after c. 2400 cal. BP is provided by increased Poaceae and Cereal-type taxa, which occur with high concentrations of plant wax n-alkanes with a dominant C3 plant origin (C27–C31 with odd/even preference, δ13C -29.8‰ to -36.3‰). Also, high concentrations of a C20 highly branched isoprenoid (HBI) thought to be from epiphytic algae associated with rice agriculture occur after c. 2400 cal. BP. 13C-depleted diploptene (in high concentrations) and 13C-depleted C31 3b-methylhopanes of methanotrophic bacterial origin also occur after c. 2400 cal. BP. The strong methane cycle detected in the trench sediment may have provided an alternative CO2 source for plants and algae associated with rice agriculture. [ABSTRACT FROM AUTHOR]

A high-resolution peat profile from the vicinity of Saariselkä (68°25.24′N, 27°25.19′E), a large tourist centre in northern Finnish Lapland, was sampled continuously at near annual resolution to a depth of 22 cm in order to interpret the changes in pollen assemblages and vegetation resulting from human interference and reindeer herding. Fifteen AMS dates were wiggle-matched with the atmospheric 14C calibration curve. The resulting age-depth model allows the calculation of pollen accumulation rates (PAR grains/cm² per yr), which, in turn, enables the fine-scale human impact to be interpreted on much better grounds than would be possible with the classical pollen percentages approach. Results indicate that increasing tourist numbers since the building of the Saariselkä resort in 1950 are not seen in the pollen diagrams. Only a slight, although clear, increase in the pollen taxa of disturbed sites (mainly Gramineae with some herb pollen taxa) can be detected from the PAR diagram after the 1950s, along with a decrease of Pinus pollen following the clearance of the ski slopes in the 1970s. Principal components analysis (PCA) of fossil pollen spectra and modern pollen analogues obtained from both natural and human-disturbed sites confirms that human interference that has affected the vegetation around Saariselkä is not visible in the pollen record to the degree that might have been expected. This is interpreted as resulting from the considerably different nature of human impact at Saariselkä, where the infrastructure is fully developed and weed species are efficiently removed. The remarkable growth of reindeer population in the area during the 1980s, however, can be observed in the peat profile through an increase in the number of coprophilous fungal spores (Podospora, Sporormiella). This increase in fungal spores occurs simultaneously with a decrease in Betula pollen, which is interpreted to be a consequence of reindeer foraging the young Betula trees and seedlings. [ABSTRACT FROM AUTHOR]

We used charcoal and fossil pollen to investigate how fire, vegetation and climate have interacted over the past 2300 years at Ferry Lake, located on a sand plain in northwestern Wisconsin. Pollen analysis shows a rapid transition from oak (Quercus spp.)-dominated woodland to a relatively open pine (Pinus spp.) forest at 1450 cal. yr BP, and a more closed-canopy pine forest beginning about 700 cal. yr BP. We calculated accumulation rates of 125–250 μm charcoal fragments (CHAR) in contiguous 0.5 cm thick sediment samples, each representing 7–10 years. Graminoid charcoal fragments were tallied separately to track the relative abundance of grass charcoal. During the oak period charcoal peaks have relatively weak periodicity and relatively high accumulation rates of grass charcoal. Charcoal peaks are less frequent (with a periodicity of 130–200 years), and larger during the open-canopy pine period, with lower grass CHAR. CHAR of both charcoal types decreases further between 1000 and 850 cal. yr BP and remains low until the period of European settlement. Several hundred years later (700 cal. yr BP) white pine pollen increases and pollen from herbaceous taxa decreases, suggesting a more mesic, closed-canopy forest. Our results demonstrate that the vegetation and fire regime at this sandplain site changed substantially, but apparently not synchronously, during the last 2300 years, a period when millennial-scale regional climate was relatively similar to modern. [ABSTRACT FROM AUTHOR]

The pollen content of three adjacent peat profiles has been analysed to study the development of pasture woodland in the small valley Combe des Amburnex (1300 m a.s.l.). Chronostratigraphy based on lowland pollen assemblages and radiocarbon dates was used to correlate and date the profiles. Forest and mire grazing occurred throughout at least the past two millennia. Before the ninth century the forest consisted of about equal parts of Abies, Fagus and Picea. Thereafter Picea increased and is today strongly dominant in the area, likely an effect of selective browsing. The central part of the valley obtained its modern structure of pastures and forests in the twelfth century, and the pasture woodland in general came into existence during the seventeenth century as an effect of extensive fire activity, possibly charcoal production. In the twentieth century grass and nutrient-demanding species increased relative to other herbs. [ABSTRACT FROM AUTHOR]

Palaeoenvironmental data, in the form of 113 counts of pollen, fungal spores and charcoal abundances, 121 counts of phytoliths and 15 AMS 14C dates (11 macrofossil and 4 bulk sediment samples), have provided a means of reconstructing the late-Holocene environmental history of Munsa archaeological site, Uganda. The data were extracted from sediment cores from what is today a papyrus swamp, located within an area described by an outermost ring of earthworks at Munsa. Sediment core data indicate the general presence of forested conditions to c. AD 1100, although there is evidence for the local presence of food plants prior to this date. Deforestation from c. AD 1100 is marked in both the pollen and phytolith records, while fungal spores indicate the presence of increased numbers of herbivores post-deforestation. Indicators of deforestation and increased herbivore numbers broadly accord with the archaeological evidence for substantial occupation of the site at Munsa and the establishment of a mixed economy based on crops, cattle and iron working. Evidence for forest recovery and reduced herbivore numbers locally from c. AD 1780 could reflect abandonment of permanent settlement at the site, possibly during or following a period of drought and/or political upheaval in the region. Fungal spores and phytoliths provide evidence of agricultural activities at Munsa that have not left an imprint on pollen records, thus supporting the case for the use of multiproxies in palaeoenvironmental research, while intercore differences between the three sediment cores analysed, although relatively minor, confirm the benefits of a multicore approach. Tentative evidence for the very early presence of Musa (cultivated edible banana) is provided and warrants further study. [ABSTRACT FROM AUTHOR]

Vegetation changes during the past 1300 years are reconstructed in western equatorial Africa using a high-resolution pollen record from Lake Kamalété. This small marshy basin (c. 5–7 ha) is located in forest–savanna mosaic in Lopé Reserve (0°43′S, 11°46′E), central Gabon. The Kamalété pollen data show the persistence over the past 1300 years of a relatively stable forest–savanna mosaic, associated with significant changes of the forest component. Three successive stages of forest dynamics occurred. First, at 1325 cal. BP, moist semi-evergreen rainforest existed around the catchment of Lake Kamalété. However, it appears from the consistent presence of >70% Gramineae pollen that the site was always primarily in savanna. Secondly, from c. 1240 to 550 cal BP, a noticeable increase in shade-intolerant plant species indicate openings in the rainforest canopy. The persistence of gap-colonizer species, such as Macaranga, Tetrorchidium and Musanga for several centuries in the rainforest, is explained by recurring canopy disturbance associated with shifts in available moisture. These hydrological changes may be related to a succession of longer and more severe dry seasons than observed today. Thirdly, at 550 cal BP, mature forest was re-established, corresponding to progressive savanna colonization by forest pioneer species such as Aucoumea klaineana, Lophira alata and Fagara macrophylla. This new phase of forest expansion coincided with a marked lithological change, indicating an increase in lake-level. It is concluded that the major vegetation changes observed are due to climatic variability, and anthropogenic action had limited influence. [ABSTRACT FROM AUTHOR]

A multiproxy study of Ballywillin Crannog, Lough Kinale, central Ireland is presented. The methodology used reveals the wealth of information that a multiproxy approach can contribute in lake settlement studies. Plant macrofossils, pollen and spores, diatoms, chironomids and Coleoptera from a lake core are used to reconstruct local and regional vegetation change and lake history to establish the age and function of the crannog. The palaeoecological evidence suggests that Ballywillin Crannog was constructed around AD 620, with its most intensive period of occupation after AD 1150. Cereals and a range of gathered fruits and nuts were brought onto and cooked on the crannog, and cereal grains were possibly stored there. [ABSTRACT FROM AUTHOR]