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Detailed palaeogeographical studies of the accumulative fan in the Serteyka River valley in W Russia and underlying biogenic deposits were carried out. The base of a representative core of biogenic sediments in the distal zone is dated to 1291 BC, while its top to 1631 AD. In this paper, palynological, plant macrofossils, Chironomide and Cladocera, geochemical, geochronological and sedimentological analysis were performed. Four phases of biogenic deposition were distinguished by pollen and geochemical analyses. Two of them coincide with the climatic fluctuation during Medieval Climate Anomaly and Little Ice Age. During the formation of the fan, overbank deposits were accumulated also, indicating numerous and intense floods, which are in line with the trend observed for other sites in this region. The accumulative fan is formed by lower, middle and upper deluvia and agricultural diamicton in its top. All units have specific sedimentological and geochemical features as well as low admixture of plant macrofossils. The beginning of the formation of this relief form dates back to the second half of the 17th century AD, and the end of the accumulation falls on the second half of the 18th century AD. Our work suggests that natural conditions had an impact on the formation and development of studied accumulative fan, however, the decisive factor causing the intensification of the slope processes were related with deforestation resulted from strong human impact, which was marked in palynological and macrofossils analyses (e.g. increase in the contribution of plants macrofossils related to agriculture). [ABSTRACT FROM AUTHOR]

Frank Oldfield's immense contribution to palaeoenvironmental science is summarized in relation to: pollen analysis, vegetation history and peat stratigraphy; palaeolimnology and 210Pb dating; environmental magnetism, catchment-lake relationships and soil erosional history; multiproxy approaches; PAGES; and editing The Holocene. The tribute includes an introduction to the 14 other papers in this Special Issue, which were inspired in diverse ways by this remarkable scientist. [ABSTRACT FROM AUTHOR]

Quantitative reconstruction of past vegetation is one of the primary goals in Quaternary palynology and palaeoecology but still remains difficult. This paper proposes a model, REVEALS, that estimates regional vegetation composition using pollen from ‘large lakes’ that have small site-to-site variations of pollen assemblages even if vegetation is highly heterogeneous. Once these data have been used to quantify regional vegetation composition within 104-105 km², background pollen, one of the parameters crucial for vegetation reconstruction, can be estimated for smaller-sized sites, and incorporated into the Landscape Reconstruction Algorithm (LRA), a multistep framework for quantitative reconstruction of vegetation in smaller areas (≤/104 ha). Simulations using the POLLSCAPE modelling show that REVEALS can provide accurate estimates of regional vegetation composition in various landscapes and under different atmospheric conditions. If pollen assemblages from lakes that are much smaller than ‘large lakes’ are used, estimates of regional vegetation at individual sites could be significantly different from the expected values, and their site-to-site variation could be large. However, when pollen data from multiple lakes ≥100-500 ha in size are available, REVEALS can provide accurate estimates of the regional vegetation with relatively small standard errors. Quantitative reconstruction of regional landscape and vegetation change will be critical for testing some of the controversial hypotheses and concepts in global change and conservation research, such as the impacts of agricultural activities on global climate over the last 8000 years and the open-woodland hypothesis in northern Europe in the early Holocene. [ABSTRACT FROM AUTHOR]

In this paper we use a simulation approach to explore the effect of variation in taxon parameters and landscape patterning on relevant source area of pollen. We use the Prentice-Sugita model, assume constant atmospheric conditions and basin morphology, and take a reductionist approach to explore the behaviour of pollen dispersal and deposition in a simple landscape scenario. Individual factors within the scenario (pollen fall speed, relative pollen productivity, size of basic unit in the landscape mosaic, patch size, rarity of individual taxa and overall number of taxa present in the landscape) are varied while all other parameters are kept constant, thus permitting exploration of the role of different components of the system. These simulations suggest that, for basins of given size under fixed atmospheric conditions, the relevant source area of pollen is primarily an expression of the patterning of the different vegetation elements within the landscape. This has important implications for the interpretation of palaeoecological records and reconstruction of past environments. Reconstruction, especially quantitative reconstruction, requires some estimate of past relevant source area of pollen. If, as our results suggest, vegetation patterning is an important determinant of this, then it must also be taken into account when attempting to reconstruct past vegetation communities. [ABSTRACT FROM AUTHOR]

On the basis of sediment and pollen analyses of a radiocarbon-dated sediment sequence from Lake Joux in the Swiss Jura Mountains (west-central Europe), this paper presents a high-resolution record of lake-level and vegetation changes for the last millennium. The lake-level record makes it possible to determine that lowstands of the water-table dominated at c. AD 1200-1400, and from 1720 onward, with interruptions by short-lived rise events at c. AD 1340 and 1840. Highstands prevailed at c. AD 1100, and around AD 1450, 1550 and 1700. The comparison of the Joux lake-level record with a solar irradiance record based on cosmogenic nucleides supports the hypothesis of a major solar forcing of climate variations in west-central Europe over the last millennium. In agreement with other palaeohydrological records established in Western Europe and in the central North Atlantic Ocean, the Joux lake-level record suggests that, on a multicentennial scale, the period of the 'Little Ice Age' coincided in the European mid-latitudes with wetter climatic conditions, and probably with an increase in summer precipitation. Variations in the hydrological cycle appear to have been associated with changes in the general atmospheric circulation pattern, probably coupled with variations in oceanic circulation and solar activity. The Joux record also points to changes in water resources expected to result from ongoing global warming. Finally, despite the severe climatic conditions which prevail in the Joux Valley, the human impact history at Lake Joux over the last millennium seems to reflect political choices and economic context more than climatic changes. [ABSTRACT FROM AUTHOR]

Abstract: A total of 237 surface soil pollen samples were collected from less disturbed zonal communities, and a new surface pollen data set has been established in northern China. Pollen-climate parameter transfer functions using weighted-averaging regression and calibration partial least squares (WA-PLS) model as a tool to reconstruct past climate changes from pollen data, were tested with this new surface pollen data set. The results of cross validation showed that the method worked very well with precipitation (R = 0.94, R2 jack = 0.89, RMSEPjack = 69 mm, the safe dynamic range of the reconstruction was 40 mm~800 mm) and worked well with temperature (Tann: R = 0.84, R2 jack = 0.71, RMSEPjack = 2.0°C, the safe dynamic range of the reconstruction was -4°C~13°C; MTwa: R = 0.79, R2 jack = 2.5°C, and the safe dynamic range of the reconstruction was 8°C~26°C), indicating that the surface pollen data set and WA-PLS reconstruction technique in this paper have strong potential for palaeoclimatic reconstruction. [ABSTRACT FROM AUTHOR]jack = 2.5°C, and the safe dynamic range of the reconstruction was 8°C~26°C), indicating that the surface pollen data set and WA-PLS reconstruction technique in this paper have strong potential for palaeoclimatic reconstruction. [ABSTRACT FROM AUTHOR]

Pollen analysis of a 48 m AMS radiocarbon-dated sediment sequence from the Guadiana estuary provides the first record of Lateglacial and Holocene vegetation history in the Algarve province of Portugal. This paper focuses on the record of terrestrial pollen taxa, which document a series of forest expansions and declines during the period 13 000 cal. BP to 1600 cal. BP and provide insights into climate evolution in southwestern Iberia. The main vegetation phases identified in the Guadiana valley are (1) Lateglacial interstadial (Allerød) forest with Quercus and Pinus under a temperate, moist, continental climate; (2) a Younger Dryas forest decline (Quercus) and expansion of pinewoods, xeric scrub and open ground habitats (with Juniperus, Artemisia, Ephedra distachya type, Centaurea scabiosa type) under arid and cold conditions; (3) an early Holocene forest/scrub/open-ground vegetation mosaic developing under a warm, dry and continental climate; (4) a maximum of Quercus forest and thermomediterranean evergreen taxa (Olea, Phillyrea, Pistacia) reflecting a warm, moist oceanic climate between c. 9000 cal. BP and c. 5000 cal. BP; and (5) the expansion of shrublands with Cistaceae and Ericaceae under a drier climatic regime and increasing anthropogenic activity since c. 5000 cal. BP. Holocene episodes of maximum climatic aridity are identified in the record of xerophytic taxa (Juniperus, Artemisia, Ephedra distachya type) centred around 10 200 cal. BP, 7800 cal. BP, 4800 cal. BP, 3100 cal. BP and 1700 cal. BP. Regional comparisons suggest a correlation of arid phases across southern Iberia and northwest Africa, which can be related to abrupt North Atlantic coolings (Bond events). [ABSTRACT FROM AUTHOR]

This paper describes our recent extraction of ancient DNA (aDNA) from Holocene pollen and discusses the potential of the technique for elucidating timescales of evolutionary change. We show that plastid DNA is recoverable and usable from pollen grains of Scots pine Pinus sylvestris from 10 ka and 100 years ago. Comparison of the ancient sequences with modern sequences, obtained from an extant population, establish a first genetic link between modern and fossil samples of Scots pine, providing a genetic continuity through time. One common haplotype is present in each of the three periods investigated, suggesting that it persisted near the lake throughout the postglacial. The retrieval of aDNA from pollen has major implications for palaeoecology by allowing (i) investigation of population-level dynamics in time and space, and (ii) tracing ancestry of populations and developing phylogenetic trees that include extinct as well as extant taxa. The method should work over the last glacial oscillation, thus giving access to ancestry of populations over a crucial period of time for the understanding of the relationship between speciation and climate change. [ABSTRACT FROM AUTHOR]

This paper examines the mid- to late-Holocene (c. 6850-1160 cal. yr BP) environmental history of Sierra de Gádor in southern Spain. The local vegetation dynamics are reconstructed through the palaeoecological record obtained from a lacustrine deposit situated at 1530 m. Various hypotheses are considered to explain the vegetation dynamics apparent in the palaeoecological evidence, including climatic change, fire occurrence and human activity. Although the vegetation in this region is sensitive to climatic change, threshold events driven by ecological factors are also apparent. Climatic events include a thermo-mesophytic optimum with abundance of deciduous trees and maximum lake water level found from c. 6850 to 5500 cal. yr BP. In contrast, changes in the frequency of major fire episodes appear to have shaped interspecific relationships and vegetation change, especially from c. 4200 cal. yr BP onwards. Biotic properties of the ecosystem such as the inertia of established tree populations, interconnected with competition adjustments, appear also to have played a role. Over the last two millennia, overgrazing, combined with natural and/or human-set fires, appears to have pushed mountain forests over a threshold leading to the spread of grassland, thorny scrub, junipers and nitrophilous communities. [ABSTRACT FROM AUTHOR]

A detailed pollen analysis has been carried out on two sediment cores taken from a marsh area located in the Doñana National Park, southwestern Spain. The studied sedimentary sequences contain a similar late Holocene record of vegetation and climate and show a progressive aridification trend since at least 5000 cal. yr BP, through a decrease in forest cover in this area. Long-term vegetation changes shown here (semi-desert expansion and Mediterranean forest decline) paralleled declining summer insolation. Decreasing summer insolation most likely impacted negatively on tree growing season as well as on winter precipitation in the area. Superimposed on the long-term aridification trend were multi-centennial scale periods characterized by forest reductions or increases in arid and halophytic plants that can be interpreted as produced by enhanced droughts and/or by local geodynamic processes. These are centered at ca. 4000, 3000–2500, and 1000 cal. yr BP, coinciding in timing and duration with well-known dry events in the western Mediterranean and other areas but could have also been generated by local sedimentary or geodynamic processes such as a marine transgression in a subsidence context and extreme wave events (EWEs). The alternation of persistent North Atlantic Oscillation modes probably played an important role in controlling these relatively humid–arid cycles. [ABSTRACT FROM PUBLISHER]

Research on modern pollen assemblages of human-induced vegetation is conducive to extracting human impact information, and provides basis for determining human impact intensity. The use of 189 surface soil pollen samples from human-induced and natural vegetation shows that there were significant discrepancies of indicator pollen taxa and human impact intensity between different vegetation types in Northern China. The results demonstrate that forest and grassland pollen assemblages are dominated by natural vegetation pollen taxa, which show little effect from human impact. Farmlands are dominated by Cereal Poaceae pollen. Cultivation methods, climate conditions and human impact intensity are the main reasons that cause discrepancy in different regions. Uncultivated lands could be effectively distinguished based on common human-companion plant pollen types and certain amount of crop pollen, which display the first step of secondary succession from human-induced to natural vegetation. Indicator species analysis shows that Cereal Poaceae, Trilete spore, Humulus and Brassicaceae indicate farmlands; weeds Poaceae, Chenopodiaceae, Ranunculaceae and Selaginella sinensis indicate uncultivated lands; grasslands have the largest number of indicator pollen taxa, in which Convolvulaceae, Artemisia, Asteraceae, Liliaceae, Polygonaceae, and Nitraria pollen have the highest indicator values; in forests, Betula, Larix and Quercus have the highest indicator values with statistical significance. Meanwhile, Human Influence Index (HII) values can be used to differentiate human-induced and natural vegetation. The calibration model of pollen-HII based on the weighted averaging plus partial least squares (WA-PLS) method exhibits a good statistical performance (R2 = 0.69), and the HII values have the same trend of change with Cereal Poaceae percentage. Our results confirm that pollen from human-induced vegetation can provide reliable estimates of HII, which provides a good reference for restoring human impact intensity in fossil pollen assemblage. [ABSTRACT FROM PUBLISHER]

Three parallel overlapping cores have been taken in the Albanian side of Lake Shkodra (Albania/Montenegro). The chronological frame of the record, spanning approximately the last 4500 years, has been assessed using four radiocarbon dates and four well-known tephra layers of Italian volcanoes. Multidisciplinary analyses turned out to be decisive to understand environmental, climatic changes and human impact. Here, we focus on palynology. The humidity at Shkodra was always enough to allow the developing of a luxuriant arboreal vegetation. The pollen percentage diagram does not record important changes in terrestrial plants percentages. Arboreal pollen (AP) shows only a rather slight decrease, with ‘natural forests’ replaced by intensive cultivation of chestnut and walnut in the last seven/eight centuries. The rather minimal changes in composition and dominance are because of the fact that the pollen rain comes from different vegetation belts, from the Mediterranean to the alpine one. Two major periods of humidity are found, one at the base of the pollen concentration and influx diagram, before 4100 yr BP, the other at 1300 yr BP. Minima in pollen influx and concentration occurred soon before 4000, at ca. 2900 and at ca. 1450 yr BP These minima, interpreted as aridity crises, show a temporal coincidence with the so-called Bond events 1-3 already found in other central and eastern Mediterranean records. The minimum in AP occurring after 500 yr BP could represent the record of the ‘Little Ice Age’, even if it could be the effect of a strong land use. [ABSTRACT FROM PUBLISHER]

This study examines the course and driving forces of recent vegetation change in the Mongolian steppe. A sediment core covering the last 55 years from a small closed-basin lake in central Mongolia was analyzed for its multi-proxy record at annual resolution. Pollen analysis shows that highest abundances of planted Poaceae and highest vegetation diversity occurred during 1977–1992, reflecting agricultural development in the lake area. A decrease in diversity and an increase in Artemisia abundance after 1992 indicate enhanced vegetation degradation in recent times, most probably because of overgrazing and farmland abandonment. Human impact is the main factor for the vegetation degradation within the past decades as revealed by a series of redundancy analyses, while climate change and soil erosion play subordinate roles. High Pediastrum (a green algae) influx, high atomic total organic carbon/total nitrogen (TOC/TN) ratios, abundant coarse detrital grains, and the decrease of δ13Corg and δ15N since about 1977 but particularly after 1992 indicate that abundant terrestrial organic matter and nutrients were transported into the lake and caused lake eutrophication, presumably because of intensified land use. Thus, we infer that the transition to a market economy in Mongolia since the early 1990s not only caused dramatic vegetation degradation but also affected the lake ecosystem through anthropogenic changes in the catchment area. [ABSTRACT FROM AUTHOR]

Climate, land use and fire are strong determinants of plant diversity, potentially resulting in local extinctions, including rare endemic and economically valuable species. While climate and land use are decisive for vegetation composition and thus the species pool, fire disturbance can lead to landscape fragmentation, affecting the provisioning of important ecosystem services such as timber and raw natural resources. We use multi-proxy palaeoecological data with high taxonomic and temporal resolution across an environmental gradient to assess the long-term impact of major climate shifts, land use and fire disturbance on past vegetation openness and plant diversity (evenness and richness). Evenness of taxa is inferred by calculating the probability of interspecific encounter (PIE) of pollen and spores and species richness by palynological richness (PRI). To account for evenness distortions of PRI, we developed a new palaeodiversity measure, which is evenness-detrended palynological richness (DE-PRI). Reconstructed species richness increases from north to south regardless of time, mirroring the biodiversity increase across the gradient from temperate deciduous to subtropical evergreen vegetation. Climatic changes after the end of the last ice age contributed to biodiversity dynamics, usually by promoting species richness and evenness in response to warming. The data reveal that the promotion of diverse open-land ecosystems increased when human disturbance became determinant, while forests became less diverse. Our results imply that the today’s biodiversity has been shaped by anthropogenic forcing over the millennia. Future management strategies aiming at a successful conservation of biodiversity should therefore consider the millennia-lasting role of anthropogenic fire and human activities. [ABSTRACT FROM PUBLISHER]

Haida Gwaii (formerly Queen Charlotte Islands) is an archipelago on the outer central coast of British Columbia. Drizzle Bog on Graham Island is a Sphagnum-dominated peatland selected for a multiproxy palaeoecological analysis using pollen, spores and other microfossils to see whether climatic changes such as the ‘Mediaeval Climate Anomaly’ (MCA), ‘Little Ice Age’ (LIA) and post-LIA warming could be detected in this hypermaritime region. A 90-cm-long Wardenaar peat core was sliced into 1-cm-thick subsamples and dated using 210Pb back to ad 1892, and four accelerator mass spectrometry (AMS) radiocarbon dates back to 1800 cal. yr BP. Low pollen accumulation rates between ~ad 1600 and 1875 support cool growing seasons during the LIA. At 34 cm (~1875), total pollen and spore accumulation rates increased dramatically, coinciding with the end of the LIA based on evidence from glacier recession in the Coast Mountains of British Columbia. We suggest that the increased pollen production is likely a reflection of climatic warming and increased vegetation productivity following the LIA. Direct human impact is only apparent above 12 cm depth (~1958) correlated with road building across the southwestern edge of the wetland. [ABSTRACT FROM PUBLISHER]

Pollen analysis is frequently used to build climate and environmental histories. A distinct Holocene pollen series exists for Chaco Canyon, New Mexico. This study reports linear modeling and hypothesis testing of long distance dispersal pollen from radiocarbon-dated packrat middens which reveal strong relationships between piñon pine (Pinus edulis) and ponderosa pine (Pinus ponderosa). Ponderosa pollen dominates midden pollen assemblages during the early Holocene, while a rapid shift to a much higher proportion of piñon to ponderosa pine pollen between c. 5440 and 5102 cal. yr BP points to an aridization episode. This shift is associated with higher δ18O values in Southwest speleothem records relative to the preceding millennium. The period of aridization is followed by a sharp increase in El Niño/Southern Oscillation events that would have caused highly variable precipitation and lasted until c. 4200 cal. yr BP. Bayesian change-point analysis suggests that this aridization episode led to stable ecotonal boundaries for at least 3000 years. The piñon/ponderosa transition may have been caused by punctuated multiyear droughts, analogous to those in the 20th century. The earliest documented instance of Zea mays cultivation on the Colorado Plateau is around c. 3940 14C yr BP (c. 4364 cal. yr BP) (Hall SA (2010) Early maize pollen from Chaco Canyon, New Mexico, USA. Palynology 34(1): 125–137) in Chaco Canyon. The introduction of this labor-intensive cultigen from Mesoamerica may have been facilitated by changes in the regional ecosystems, specifically by an increase in piñon trees, that promoted increasing human territoriality. Linear modeling and hypothesis testing can complement traditional palynological techniques by adding greater resolution in vegetation patterning to climate/environmental histories. [ABSTRACT FROM AUTHOR]

Pollen and spore analysis is the most successfully used palaeobotanical discipline for reconstructing Holocene vegetation and climate history throughout the world. Subantarctic islands are very specific areas. They are located in the circum-Antarctic Southern Ocean in latitudes that are under strong influence of the southern westerly winds, and are characterised by a treeless, phanerogam-poor flora. Palynological research on many of these islands has resulted in diverging conclusions about how to infer climate history from pollen data. In this study we compare pollen data with macrofossil data on the one hand, and the palaeoenvironmental history based on a multiproxy record on the other hand, of two peat sequences from two different subantarctic islands, South Georgia and Île de la Possession (Îles Crozet). We conclude that palynology must be used with caution as a proxy for climate change on these islands, especially when no other proxy data are available. The upland–lowland principle, as it has been applied in pollen studies in the South Indian Ocean islands, results in erroneous conclusions about climate change on Île de la Possession. More palaeoclimatic multiproxy and pollen studies, in combination with pollen–vegetation relationship studies, can, however, contribute to a more reliable model of how to interpret pollen data in the Subantarctic. We want to stress that our conclusions are only based on Holocene records. Consequently, the question remains if palynology can be used as a palaeoclimatic proxy when climatic changes were more pronounced such as during the last glacial–interglacial transition. [ABSTRACT FROM PUBLISHER]

Pollen analysis of a core in Princess Vlei in the Fynbos Biome near Cape Town gives a 4150 year record of vegetation and climate changes followed by disturbance by colonial settlers since c. 300 years ago. Their impact replaced climate as a major factor in changing the vegetation. The chronology is based on eight radiocarbon dates. Pollen types such as Restionaceae, Ericaceae, and Proteaceae reflect changes in fynbos. Pollen indicators at the bottom of the core suggest drier conditions followed by an increase in Morella, Cyperaceae and Carpacoce pollen, which might indicate moist conditions c. 3400–2600 cal. yr BP. Drier conditions prevail c. 2600–1900 cal. yr BP. Apparent light disturbance after c. 2000 cal. yr BP might be attributed to Khoi herders. Deeper water and damp surroundings are indicated c. 1900–1000 cal. yr BP. The top of the core shows an increase of Poaceae while Restionaceae decrease with anthropogenic disturbance, including the introduction of neophytes such as Pinus (c. 300 years ago) and Zea mays. Charcoal percentages point to intense fires after the arrival of the Europeans. Water between 105 and 75 cm indicates the development of a floating mat resulting from changes in the hydrological system possibly connected to disturbances by settlers. [ABSTRACT FROM PUBLISHER]

Fossil pollen from Nam Co and modern pollen from altitudinal vegetation belts around the lake are investigated to reveal alpine vegetation succession in response to climate changes during the Holocene in the central Tibetan Plateau. The discriminant analysis on 37 topsoil samples shows that pollen samples from alpine steppe at lower elevations (<4800 m) and alpine meadow on upper slopes (4800–5200 m) can be distinguished by their pollen assemblages. Samples from alpine steppe contain more Artemisia (25.1%) and Poaceae pollen (11.5%), whereas those from alpine meadow are dominated by Cyperaceae pollen (>60%). Our result indicates that the pollen ratio of Artemisia to Cyperaceae (A/Cy) can be used as an indicator of the vertical shift of vegetation belts and temperature changes in the central Tibetan Plateau as suggested by previous studies. A history of the vertical shift of vegetation belts on the northern slope of Nyainqentanglha Mountains and climate changes since 8.4 kyr BP are thus recovered by 198 fossil pollen assemblages from a 332 cm core of Nam Co. Paleovegetation reconstructed from fossil pollen assemblages through discriminant analysis shows a general downward shift of altitudinal vegetation belts, suggesting a decline in the temperature trend since 8.4 kyr BP. This result is consistent with the reduction of A/Cy ratios. The fossil pollen record also reveals warm and wet climate during the early to mid Holocene, and cold and dry conditions during the late Holocene in the Nam Co area. A comparison of Holocene climatic reconstructions across the Plateau indicates that termination of maximum moisture at around 6–5.5 kyr BP in our record is associated with the southeastward retreat of the Southwest Monsoon. [ABSTRACT FROM AUTHOR]

Three sediment cores, from one upland and two lowland sites on Nuku Hiva, Marquesas Islands, provide a c. 750-year record of palaeo-environmental change on the island. Accelerator mass spectrometry (AMS) dating of pollen concentrates from the base of each core indicates that the three widely separated marshes developed c. AD 1200 and 1350, after the known period of human colonisation and establishment. Detailed analyses (pollen, sediments, and charcoal) and additional dating of the upland core from Tōvi’i Plateau (810 m) allow for identification of four chronozones. The core sediment data and age-depth curve suggest an alternation of wet-dry-wet conditions over the c. 750-year period. The pollen spectra, in contrast, are fairly stable, with ferns dominating but arborescent species also present. The micro-charcoal evidence points to regional burning and long-distance transport until c. AD 1640, after which localised burning may be indicated. Among the more notable changes is a major increase in pollen and spore deposition after c. AD 1640, a trend most evident in the pollen concentration diagram. Overall, the data suggest rapid sedimentation in the fourteenth century AD, followed by drier and/or more settled conditions until the mid-seventeenth century, and finally wetter conditions after c. AD 1640. The latter in particular is consistent with emerging regional evidence for warm-wet conditions in the central eastern Pacific during the seventeenth century, the height of the Northern Hemisphere ‘Little Ice Age’. The charcoal record also provides insights into human activities on the island, suggesting burning in the lowlands from the fourteenth century AD, probably in conjunction with forest clearance preparatory to tree and root crop cultivation. [ABSTRACT FROM AUTHOR]

Relatively little is known about the long-term response of Caribbean mangroves to human and natural disturbances during the 'Little Ice Age' (LIA). We present new palynological information on the dynamics of the Bahia Honda mangrove from the eastern coast of San Andres Island in the southwestern Caribbean for the late Holocene. Major changes in the Bahia Honda pollen record show the combined effects of natural events (strong storms and sealevel rise), and human disturbances. These changes are supported by 14C dates, sedimentological and palynological information. A storm (most probably a hurricane) was recorded around AD 1600, caused sediment reworking and the subsequent loss of about 2000 years of the vegetation record. The devastation of tree vegetation by this event allowed the expansion of heliophytic vegetation (e.g. grasses and vines). Mangroves and coastal vegetation started to recover at AD 1700, reaching their maximum extent within a few decades, when microforaminifera shells became abundant at the coring site, thus suggesting a relative sea-level rise because of the geomorphic reconfiguration of the coastal plain after the storm. Furthermore, the pollen evidence indicates more humid regional climates during the late LIA (AD 1700-1850). Mangrove and coastal vegetation declined sharply as a consequence of the establishment of coconut plantations around AD 1850. The recovery of the mangroves after AD 1960 is a result of the combined effect of relative sea-level rise and drastic changes in the local economy from coconut plantations to commerce. [ABSTRACT FROM AUTHOR]

We studied the relationships between surface pollen spectra, vegetation and selected climate characteristics along a strong gradient of climate continentality across the Western Sayan Mountains, southern Siberia. Representation of 111 pollen taxa in 81 surface samples from steppe, forest and tundra was related to the vegetation composition at various distances from the sampling point and to mean annual precipitation and mean July and January temperatures. These relationships were assessed by the decision tree models. The results show (1) which vegetation types are well distinguished by their pollen spectra; (2) which vegetation types are strongly similar in their pollen spectra and therefore their interpretation from fossil pollen spectra should be carefully considered; (3) tight relationship between surface pollen spectra and selected climate characteristics, which suggests that the past climatic conditions can be reasonably predicted from pollen spectra; and (4) an important role of weak pollen producers for assignment of pollen spectra to vegetation types or particular values of temperature and precipitation. We found the decision trees suitable for analysis of pollen/vegetation relationship because they (1) formally and precisely assign the pollen spectra to vegetation/landscape types or climatic variables by means of easy-to-interpret graphs; (2) identify pollen taxa that are best indicators of a particular vegetation type, landscape or climate characteristics; and (3) utilize the pollen signal of both strong and weak pollen producers. We compare the decision tree models with ordination and cluster analysis and suggest further applications. [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 Global Pollen Database is an example of a successful data synthesis effort that has uses for biogeographical and climate change studies. Results are of interest in many fields of physical geography. Continental-scale maps of past conditions have been used in data-model comparison studies. Time series, developed by averaging quantitative reconstructions from many sites, have indicated that millennial-scale climate variability has affected the vegetation of Europe and North America during the Holocene. Major transitions in the vegetation of Europe and North America occurred at the same time, suggesting the overriding climate effect on the vegetation of both continents. The database can also be used to test biogeographical hypotheses, as several examples illustrate, without the need for collecting new data. Hundreds of studies over the past 50 years show that pollen analysis is more precise than frequently acknowledged: vegetation responds rapidly to climate variations, changes in vegetation are spatially coherent and the taxonomic resolution available in the database is greater than frequently acknowledged. The availability of a public, freely available database enables different analyses to be performed on the same data, thereby ensuring that results are not dependent on methodology. [ABSTRACT FROM AUTHOR]

Pollen analysis of the peat in a small mire on the northern slope of the Alborz Mountains (550 m a.s.l.) in the Central Caspian forests of Iran reveals changes in forest and wetland vegetation during the last millennium.A forest, principally of Alnus and Carpinus occurred over almost the whole period. Quercus, Ulmus and Parrotia were less common, while Fagus, Pterocarya, Acer and Diospyros fluctuated as a probable result of human interference and/or climatic change. Two phases of clay deposition in the mire can be dated to the 'Mediaeval Climatic Anomaly' (AD 1100) and the beginning of the 'Little Ice Age' (AD 1560-1600). Although human activity seems to have persisted in the region during the whole of the past millennium, increased NAP values point to intensified human interference since the beginning of the nineteenth century. [ABSTRACT FROM AUTHOR]

The article discusses the impetus on the dynamic changes in the movements of savanna and forestecosystems. It states that the study of changes in savanna and seasonally dry forest remains dominated by palynology. It asserts that changes in the balance of water, fire frequency and carbon dioxide levels all played significant roles in the movements in savanna and forestecosystems and their importance differ from place to place. It stresses the need to integrate other types of proxies to improve the knowledge of the people on what contributes vegetation change. It adds that anthropogenic climate change in the future is likely to impose increased stresses in the ecosystem.

High-resolution analysis of ombrogenous peats often reveals pollen frequencies that change markedly from one sample to the next, indicating limited postdepositional mixing. This raises the question whether - with sufficiently thin samples - seasonal differences in pollen deposition can be observed. Seasonal resolution in peat would provide a dating technique with an accuracy similar to that of other, annually banded archives. To study the limits of temporal resolution, contiguous 0.5 mm thick slices of slightly humified Sphagnum section Cuspidata peat were palynologically analysed. No seasonal patterns in the pollen stratigraphy could be observed. This is ascribed to the mixing of pollen grains as a result of small-scaled vertical water movements and to the horizontal mode of shoot layering in the Sphagnum species. The latter process may also be the cause of a smoothed annual signal. Because of the absence of seasonal differentiation, the palynological distinction of annual peat layers is not feasible. [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]

The article discusses the pollen analysis conducted in East and Southern Africa which is associated with the vegetation and climatic changes in several localities in the area. It focuses on theoretical concerns as to how the tropics and subtropics had responded to the expansions and contractions of ice sheets in the Northern Hemisphere. It is stated that the work defines the very essence of Quaternary palaeoenvironmental reconstruction and demonstrates how fieldwork supported by meticulous and painstaking laboratory and statistical analysis can reveal a scientifically robust and insightful history of the physical environment. The study was considered crucial to the resolution of a fascinating complex of tropical and subtropical environmental changes in the African continent.

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]

Subfossil pollen from two bogs in temperature-sensitive, high-altitude regions were analysed in order to reconstruct early- to mid-Holocene summer temperature fluctuations in the Eastern Alps. The pollen records showed four centennial-scale cooling intervals with low growing-season temperatures, resulting in decreasing pollen production and/or lower treeline position during the period 9000–6000 cal. BP. For the first time, the 8200 cal. BP cold event and an equivalent to the Misox cold phase in the Swiss Alps were detected in the Eastern Alps. The oscillations recorded in the pollen curves for Swiss stone pine (Pinus cembra) and sedges (Cyperaceae) at c. 8200 cal. BP match, in time and magnitude, the δ18O excursion in the Greenland GRIP ice-core record as well as sea-surface cooling in the North Atlantic. The close congruence between the pollen records covering 3000 years and climate proxy-data from both Hemispheres indicates that large-scale environmental changes, possibly caused by North Atlantic freshwater pulses and/or fluctuations in solar activity, caused decreases in pollen production and/or treeline shifts in the Alps. Although the 8200 cal. BP climatic deterioration was of a global character, its impact on biological productivity of temperature-sensitive sites at high altitude has only rarely been demonstrated. The data indicate that pollen analyses near and above the timberline within high-altitude, herb-dominated plant communities are of considerable and yet largely unexplored potential to detect abrupt short-term as well as long-term climatic variations. [ABSTRACT FROM AUTHOR]

To investigate the Holocene vegetation history and shoreline displacement along the southeastern Swedish coast, two radiocarbon dated pollen, macrofossil and mineral magnetic sequences were studied in the western Blekinge coast: Hunnemara Lake and Smygen Bay. Both pollen records show mosaic vegetation with grasslands, heaths and woodlands prior to 11 300 cal. BP. Pinus -dominated mixed forest was initially established by 11 000 cal. BP. By 10 000 cal. BP, mixed forest with higher species diversity was fully established. Expansion of broad-leaved trees began at about 8600 cal. BP, indicating the onset of the mid-Holocene thermal maximum in Scandinavia. Following the Ulmus decline 5800 cal. BP, the regional forest became much more open due to increased human disturbance. Both basins were isolated during the period of 11 300 – 11 000 cal. BP, and subsequently in contact with the Ancylus Lake between 10 700 and 9800 cal. BP. Low abundance of brackish-water diatoms at Smygen suggests that this basin was connected with the Baltic Sea between 9800 and 8600 cal. BP, corresponding to the Early Littorina Sea phase. Hunnemara was isolated during this period. The two basins were in turn flooded at 8600 and 8300 cal. BP, as a result of global sea-level rise. A sedimentary hiatus (8300 – 7500 cal. BP) was present at Hunnemara, probably caused by a rapid sea-level rise related to global meltwater pulse 3. Aquatic macrofossil and mineral magnetic proxies reveal several minor transgressions at both sites, probably regulated by centennial-scale variations in regional storminess. Hunnemara was isolated from the Baltic Basin by 3100 cal. BP, concurrent with a lowering of the sea level at Smygen. [ABSTRACT FROM AUTHOR]

The Dahomey Gap, a savanna corridor interrupting the zonal West African rain forest, did not exist during the mid-Holocene. The pollen diagram from Lac Sélé (7°9′N, 2°26′E) indicates that in southern Benin a semi-evergreen rainforest prevailed between c. 8400 and 4500 cal. yr BP. The mid-Holocene marine transgression caused a spread of mangrove forest along the inland lagoons. Pollen analysis and geochemistry indicate that the Dahomey Gap became established at the onset of the late Holocene due to an abrupt climatic change between c. 4500 and 3400 cal. yr BP. Drier climatic conditions led to a rapid deterioration of the rain forest and subsequent spread of Sudano-Guinean savannas. A return to wetter climatic conditions between c. 3300 and 1100 cal. yr BP resulted in a rise in the lake level and a renewed spread of forests into the savanna. During this time the Dahomey Gap consisted of a forest-savanna mosaic with a high number of pioneer tree taxa including the oil palm Elaeis guineensis. After c. 1100 cal. yr BP the lake level dropped again and the Lac Sélé profile indicates drier environmental conditions resulting in the establishment of an open savanna which persists until present. The palaeorecord from Lac Sélé suggests that the role of humans in shaping the West African savannas has been overestimated. The opening of the Dahomey Gap and spread of the oil palm E. guineensis can now be confidentially attributed to climatic change and was not initiated by humans. [ABSTRACT FROM AUTHOR]

A fossil pollen and charcoal record from a cyperaceous swamp on the Fleurieu Peninsula, South Australia, was investigated to provide a history of pre- and post-European settlement vegetation change. It was found that the swamp initiated sometime before 8220 calibrated years BP. High rates of peat development and the expansion of swamp species between 7000 BP and 4500 cal. BP indicated wet conditions at that time. The swamp became drier in the late Holocene and some peat may have been lost through deflation. Macroscopic charcoal and Typha pollen suggested that Aborigines deliberately burned the upland wetlands during the mid to late Holocene. Prior to European settlement climate changes generated community shifts in the terrestrial vegetation. The record revealed a transition from an early-Holocene Eucalyptus woodland to an Allocasuarina wet-heath in the humid mid-Holocene, a community type with no modern analogue in the region. In the drier late Holocene, a Eucalyptus -dominated woodland returned. The impacts of European settlement were clearly seen in changes in sedimentation rates and in both terrestrial and wetland flora. Allocasuarina verticillata declined early in the European period and fire-tolerant species were promoted, before the almost complete removal of native vegetation through broad-scale land clearance and its replacement with nonnative pasture species. Compositional changes to the swamp flora were marked through the European phase with Acacia expanding early in settlement and later being replaced by Leptospermum, in response to changed fire and regional hydrological regimes. The impact of European land use is discussed in relation to Holocene climate-driven vegetation changes and aspects of Aboriginal land use. [ABSTRACT FROM AUTHOR]

Pollen, plant macrofossil and charcoal records from two neighbouring crater lakes (Lake Wandakara and Lake Kasenda) in lower montane (altitude ~1200 m) western Uganda (0.5°N, 30°E) reveal major changes in local and regional vegetation over the last 1200 years, which can be related to regional variations in climate (especially effective precipitation) and human impact. The biological signals are supplemented by evidence from physical sedimentary analyses (magnetic susceptibility, loss-on-ignition, dry mass accumulation rate) for major catchment changes in a wider regional context. From AD 750 to 900, medium-altitude moist forest existed around Lake Kasenda, which was largely replaced by grassland by AD 1000, coincident with evidence for increased catchment erosion and fire events, linked to human impact during a brief arid phase. Despite wetter conditions from AD 1000 to 1200 and in the 1400s, grassland prevailed around both sites until c. AD 1700—1750, with increased catchment disturbance from AD 1600 to 1700, shortly before the abandonment of major regional settlements and a switchto dispersed homesteads more reliant on pastoralism. Bothsites show the return of semi-deciduous and swamp forest from c. AD 1700 to 1800, withtree and shrub pollen remaining high until the most recent times. Pollen assemblages reveal increasingly clear human impact on local and regional vegetation in the twentieth century, which obscures any climate signal. Pollen signals may not be sensitive to all climatic fluctuations (e.g., late eighteenth-early nineteenth-century aridity), but appear to record the varying impacts on vegetation communities of both climate and human activity over long timescales. Other proxies should be analysed to disentangle further the relative importance, and interactions, of these two major drivers of environmental change in tropical Africa in recent millennia. [ABSTRACT FROM AUTHOR]

July mean temperatures and annual precipitation during the last 9000 years were inferred using the pollen record from Chuna Lake, Kola Peninsula, Russia. A quantitative pollen-climate model was generated using the best modern analogues method from a training set of 99 surface pollen spectra from the Kola Peninsula, northern Fennoscandia and Karelia. According to the evidence from Chuna Lake, the early and mid-Holocene (c. 9000— 5000 cal. BP) was warm and dry in the central Kola Peninsula with July temperatures being 1.5–2°C higher than at present. The onset of warm and dry early to mid-Holocene occurred in the Kola Peninsula earlier than in the rest of northern Fennoscandia. July temperature started to decrease and annual precipitation increased from c. 5000 cal. yr BP and climate became cool and moist. [ABSTRACT FROM AUTHOR]

Evidence for early-Holocene environments in the Wadi Faynan in the rift-margin in southern Jordan is described. The early Holocene of Jordan is not well known and palynology, plant macrofossils and molluscs from Wadi Faynan provide evidence for a much more humid – forest-steppe and steppe – environment than the present stony desert and highly degraded steppe. The early-Holocene fluvial sediments in the Faynan catchment are predominantly fine-grained, epsilon crossbedded and highly fossiliferous. They provide convincing evidence for meandering perennial rivers before 6000 cal. BP. It is prob- able that this early-Holocene landscape was disrupted by the impact of early farmers and by climate change – the 8.1 ka event appears to be marked by desiccation. By the Chalcolithic, environmental degradation was well advanced. [ABSTRACT FROM AUTHOR]

Results of a fossil Coleoptera (beetle) fauna from a fen edge sequence from Hatfield Moors, Humber-head Levels, England, are presented, Mire ontogeny inferred from this location and others are discussed, particularly in the light of previous palynological and plant macrofossil investigations. Peat initiation across most of the site centres around 3000 cal. BC, characterized by a Calluma-Eriophorum heath with areas of Pinus-Betula woodland. The onset of peat accumulation on the southern margins of the site was delayed until 1520 1390 cal. BC and appears to overlap closely with a recurrence surface at a pollen site (HAT 2) dated to 1610 1440 cal. BC, suggesting that increased surface wetness may have caused mire expansion at this time. The faunas illustrate the transition from eutrophic and mesotrophic fen to ombrotrophic raised mire, although the significance of both Pinus- and Calluna-indicating species through the sequence suggests that heath habitats may have continued to be important. Elsewhere, this earlier phase of rich fen is lacking and mesotrophic mire developed immediately above nutrient-poor sands, with ombrotrophic conditions indicated soon after. Correspondence analysis of the faunas provides valuable insights into the importance of sandy heath habitats on Hatfield Moors. The continuing influence of the underlying coversands suggests these may have been instrumental in mire ontogeny. The research highlights the usefulness of using Coleoptera to assess mire ontogeny, fluctuations in site hydrology and vegetation cover, particularly when used in conjunction with other peatland proxies. The significance of a suite of extinct beetle species is discussed with reference to forest history and climatic change. [ABSTRACT FROM AUTHOR]

Lacustrine sediments from Lago di Pergusa in central Sicily provide a Postglacial record of environmental change in the Mediterranean. Magnetic susceptibility measurements, lithofacies characterization and pollen analysis were carried out and integrated to obtain a better reconstruction of the past 11000 years. The chronology is provided by AMS radiocarbon dates on macrofossils or bulk sediment, and by a tephra correlative with a late-Holocene explosion from the Etna volcano. The transition period related to the present interglacial reafforestation, characterized by increasing humidity, started about 10700 years BP. The onset of the wettest conditions of the Postglacial occurred at about 9000 years BP and lasted until about 7200 years BP. Then a trend towards aridification began, leading to very dry conditions at about 3000 years BP. An unquestionable human impact on vegetation is found from 2800 years BP, although earlier land use cannot be excluded. As the climate had already induced change in the vegetation, the well-known human occupancy during the last three millennia did not produce strong effects on the environment. [ABSTRACT FROM AUTHOR]

Auckland Island is a small uninhabited Subantarctic island south (c.51°S) of the New Zealand mainland. It is the southernmost outpost of tall forest in the southwest Pacific. Pollen analysis of two closely adjacent peat cores near tree-line documents climate change and forest dynamics during the Lateglacial and Holocene. After the retreat of glaciers before 15 000 14 C yr BP, mountain tundra communities dominated on mineral soils under a cooler (c.3°C lower) climate than now. By 11 000 14 C yr BP, a transition to Chionochloa antarctica grassland and peaty soils was complete, and by 10 000 14 C yr BP shrub/grassland became dominant. Forest tree species (Metrosideros umbellata, Dracophyllum longifolium and Raukaua simplex) spread slowly from 10–000 14 C yr BP, but did not form tall forest until 5500–4000 14 C yr BP, despite southern ocean temperatures being warmer in the early Holocene. We suggest that warm, cloudy, low-radiation environments inhibited forest growth during the early Holocene in this intensely oceanic setting, through promoting saturated soils and reducing net photosynthesis. It was only in the later Holocene, when increased westerly windflow brought sunnier, although cooler and windier, climates, that forest expansion occurred on sheltered lowland sites. The forest at the study site collapsed to scrub at least twice within the last 2000 years, most likely because of extended periods of saturated soils. [ABSTRACT FROM AUTHOR]

This study presents the results of pollen analysis and radiocarbon dates of a peat section from Ortino, in the Pechora lowland in northern Russia. A pollen stratigraphy is provided for at least the last 9200 years and it provides a basis for the reconstruction of the vegetational and mire history in the northernmost part of European Russia. Conifer stomata content was recorded as a complement to pollen studies to achieve a better resolution of tree-line fluctuations. The onset of Holocene warming initiated a vegetation succession that started first with herb-dominated tundra vegetation, and later with herb-shrub tundra. Combined pollen and stomata evidence suggests that Picea accompanied by Betula spp. spread to Ortino soon after 9000 14 C yr BP. Trees and a climate warmer than at present persisted until c. 3000 14 C yr BP, when forests disappeared and modern dwarf-shrub tundra vegetation developed. [ABSTRACT FROM AUTHOR]

A volcanic ash-layer in peat from northern Scotland has been identified and coincides exactly with an abrupt decline in Pinus sylvestris L. (Scots pine) pollen frequencies. This provides an isochrone (time-equivalent marker horizon) with which to investigate the timing of the Holocene 'pine-decline'. Furthermore, two possible causes of the southward shift of the range of Pinus in Scotland c. 4000 BP are suggested; a direct effect of acid pollution by chemicals produced by the eruption of Hekla (H-4), or a volcanically-induced climatic perturbation. These possibilities have wider implications for the influence of volcanism on postglacial environmental change. [ABSTRACT FROM PUBLISHER]