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Reliable quantitative vegetation reconstructions for Europe during the Holocene are crucial to improving our understanding of landscape dynamics, making it possible to assess the past effects of environmental variables and land-use change on ecosystems and biodiversity, and mitigating their effects in the future. We present here the most spatially extensive and temporally continuous pollen-based reconstructions of plant cover in Europe (at a spatial resolution of 1° × 1°) over the Holocene (last 11.7 ka BP) using the 'Regional Estimates of VEgetation Abundance from Large Sites' (REVEALS) model. This study has three main aims. First, to present the most accurate and reliable generation of REVEALS reconstructions across Europe so far. This has been achieved by including a larger number of pollen records compared to former analyses, in particular from the Mediterranean area. Second, to discuss methodological issues in the quantification of past land cover by using alternative datasets of relative pollen productivities (RPPs), one of the key input parameters of REVEALS, to test model sensitivity. Finally, to validate our reconstructions with the global forest change dataset. The results suggest that the RPPs.st1 (31 taxa) dataset is best suited to producing regional vegetation cover estimates for Europe. These reconstructions offer a long-term perspective providing unique possibilities to explore spatial-temporal changes in past land cover and biodiversity. [ABSTRACT FROM AUTHOR]

Holocene temperature changes and their forcings serve as pivotal references for current and future warming trends. However, significant discrepancies exist between proxy reconstructions and model simulations of Holocene temperature evolution. Pollen evidence, often central to these discrepancies, have been criticized for potentially reflecting human influence rather than pure temperature variations, complicating our understanding of Holocene temperature changes. Our study focuses on southern China, a region with pronounced discrepancies between models and proxies. We introduce and validate a novel methodology to isolate genuine temperature signals from pollen data. This approach employs an arboreal pollen-based temperature index and correct biases inherent in raw pollen data using the Regional Estimates of Vegetation Abundance from Large Sites (REVEALS) model. Applying this method, we present a new winter/annual temperature record for the past 10,000 years based on two fossil pollen data from the Luoxiao Mountains. Simultaneously, we reconstruct the historical impact of human activities in the region. Our temperature records reveal a sustained warming trend during the Holocene, closely matching model-simulated mean annual temperatures (R = 0.97), and temperature reconstructions based on branched glycerol dialkyl glycerol tetraethers from regional terrestrial and marine archives. In contrast, uncorrected pollen data indicate a cooling trend during the late Holocene, coinciding with significant human impact since approximately 3 ka BP. Our analysis and regional comparison with existing temperature records indicate that such contrasting temperature trends stem from a human-induced cooling bias, particularly pronounced in uncorrected pollen data. We infer that the early to middle Holocene warming was due to various factors, while late Holocene warming was predominantly driven by local annual insolation changes. Our findings challenge previously widely identified late-Holocene cooling trends based on uncorrected pollen data, demonstrating that the correction of pollen data can effectively mitigate human-induced cooling biases in temperature reconstructions. This study confirms the accuracy of climate models in simulating a Holocene warming trend, both temporally and spatially, at least in southern China. • Correcting pollen data mitigates human-induced cooling bias effectively. • A novel pollen record indicates long-term Holocene warming in southern China. • Climate models are valid in simulating Holocene temperature changes in southern China. • Late Holocene warming in southern China is driven by rising annual insolation. [ABSTRACT FROM AUTHOR]

The onset of agriculture improved the capacity of ecosystems to produce food, but inadvertently altered other vital ecosystem functions. Plant traits play a central role in determining ecosystem properties, therefore we investigated how the onset of agriculture in Europe changed plant trait composition using 78 pollen records. Using a novel Bayesian approach for reconstructing plant trait composition from pollen records, we provide a robust method that can account for trait variability within pollen types. We estimate an overall four‐fold decrease in plant size through agriculture and associated decreases in leaf and seed size. We show an increase in niche space towards the resource‐acquisitive end of the leaf economic spectrum. Decreases in leaf phosphorus might have been caused by nutrient depletion through grazing and burning. Our results show that agriculture, from its start, has likely been gradually impacting biogeochemical cycles through altered vegetation composition. [ABSTRACT FROM AUTHOR]

Weighted distribution is a valuable method for constructing flexible models and analyzing data sets. In this paper, a new weighted distribution of skew-normal is introduced with four parameters. The proposed model is a generalized version of several distributions, such as normal, bimodal normal, skew-normal, and skewed bimodal normal-normal. This weighted model is form-invariant under the proposed weight function. The basic characteristics of the model are expressed. A method has been used to generate data from the model. The maximum likelihood estimations of parameters are given and evaluated using a simulation study. The model is fitted to the three real data sets. The advantage of the proposed model has been shown on the rival distributions using appropriate criteria. [ABSTRACT FROM AUTHOR]

Aim: Biomisation has been the most widely used technique to reconstruct past regional vegetation patterns because it does not require an extensive modern pollen dataset. However, it has well‐known limitations including its dependence on expert judgement for the assignment of pollen taxa to plant functional types (PFTs) and PFTs to biomes. Here we present a new method that combines the strengths of biomisation with those of the alternative dissimilarity‐based techniques. Location: The Eastern Mediterranean‐Black Sea Caspian Corridor (EMBSeCBIO). Taxon: Plants Methods: Modern pollen samples, assigned to biomes based on potential natural vegetation data, are used to characterize the within‐biome means and standard deviations of the abundances of each taxon. These values are used to calculate a dissimilarity index between any pollen sample and every biome, and thus assign the sample to the most likely biome. We calculate a threshold value for each modern biome; fossil samples with scores below the threshold for all modern biomes are thus identified as non‐analogue vegetation. We applied the new method to the EMBSeCBIO region to compare its performance with existing reconstructions. Results: The method captured changes in the importance of individual taxa along environmental gradients. The balanced accuracy obtained for the EMBSeCBIO region using the new method was better than obtained using biomisation (77% vs. 65%). When the method was applied to high‐resolution fossil records, 70% of the entities showed more temporally stable biome assignments than obtained using biomisation. The technique also identified likely non‐analogue assemblages in a synthetic modern dataset and in fossil records. Main conclusions: The new method yields more accurate and stable reconstructions of vegetation than biomisation. It requires an extensive modern pollen dataset, but is conceptually simple, and avoids subjective choices about taxon allocations to PFTs and PFTs to biomes. [ABSTRACT FROM AUTHOR]

Reliable quantitative vegetation reconstructions for Europe during the Holocene are crucial to improving our understanding of landscape dynamics, making it possible to assess the past effects of environmental variables and land-use change on ecosystems and biodiversity, and mitigating their effects in the future. We present here the most spatially extensive and temporally continuous pollen-based reconstructions of plant cover in Europe (at a spatial resolution of 1° × 1°) over the Holocene (last 11.7 ka BP) using the ‘Regional Estimates of VEgetation Abundance from Large Sites’ (REVEALS) model. This study has three main aims. First, to present the most accurate and reliable generation of REVEALS reconstructions across Europe so far. This has been achieved by including a larger number of pollen records compared to former analyses, in particular from the Mediterranean area. Second, to discuss methodological issues in the quantification of past land cover by using alternative datasets of relative pollen productivities (RPPs), one of the key input parameters of REVEALS, to test model sensitivity. Finally, to validate our reconstructions with the global forest change dataset. The results suggest that the RPPs.st1 (31 taxa) dataset is best suited to producing regional vegetation cover estimates for Europe. These reconstructions offer a long-term perspective providing unique possibilities to explore spatial-temporal changes in past land cover and biodiversity.

Historical biome changes on the Tibetan Plateau provide important information that improves our understanding of the alpine vegetation responses to climate changes. However, a comprehensively quantitative reconstruction of the historical Tibetan Plateau biomes is not possible due to the lack of quantitative methods that enable appropriate classification of alpine biomes based on proxy data such as fossil pollen records. In this study, a pollen-based biome classification model was developed by applying a random forest algorithm (a supervised machine learning method) based on modern pollen assemblages on and around the Tibetan Plateau, and its robustness was assessed by comparing its results with the predictions of the biomisation method. The results indicated that modern biome distributions reconstructed using the random forest model based on modern pollen data generally concurred with the observed zonal vegetation. The random forest model had a significantly higher accuracy than the biomisation method, indicating the former is a more suitable tool for reconstructing alpine biome changes on the Tibetan Plateau. The random forest model was then applied to reconstruct the Tibetan Plateau biome changes from 22 ka BP to the present based on 51 fossil pollen records. The reconstructed biome distribution changes on the Tibetan Plateau generally corresponded to global climate changes and Asian monsoon variations. In the Last Glacial Maximum, the Tibetan Plateau was mainly desert with subtropical forests distributed in the southeast. During the last deglaciation, the alpine steppe began expanding and gradually became zonal vegetation in the central and eastern regions. Alpine meadow occupied the eastern and southeastern areas of the Tibetan Plateau since the early Holocene, and the forest-meadow-steppe-desert pattern running southeast to northwest on the Tibetan Plateau was established afterwards. In the mid-Holocene, subtropical forests extended north, which reflected the "optimum" condition. During the late Holocene, alpine meadows and alpine steppes expanded south. [ABSTRACT FROM AUTHOR]

New investigations of the Krasnaya Gorka site suggest the emergence of pottery in the Late Pleistocene-Early Holocene in the Transbaikal region. Several new AMS dates obtained for the early ceramic cultural layer 2 indicate an age between 13900-10500 cal BP. The results of palynological studies of the Krasnaya Gorka deposits are given in the paper for the first time, and the Late Pleistocene-Holocene environmental changes were reconstructed. Pollen data obtained from the Krasnaya Gorka profile showed cold and dry Late Pleistocene environmental conditions. The regional climate became milder and more humid around 13900–12700 cal BP, which corresponds to the Allerød interstadial thus corroborating the radiocarbon age results. The warmest interval of the Late Pleistocene occurred around 13500 cal BP. Between 12700 and 11800 cal BP, cooling probably corresponds to the cold and dry event of the Younger Dryas. There is some stratigraphical in deposits of the Krasnaya Gorka archeological site. The deposits forming in the early Holocene and beginning of the middle Holocene most likely were removed by erosion. Warming and increased humidity occurred in middle of the late Holocene (2700-1800 cal BP). During the late Holocene, the climate was unstable. Beginning 400 cal BP, the vegetation of the region acquired its modern appearance. Some published materials concerning reconstructions of paleoclimate in the region of Ust'-Karenga XII, Studenoe I, and Ust'-Menza I are considered in the context of general characteristics of the region. Therefore, both palynological reconstructions and radiocarbon dates place the earliest ceramics from Krasnaya Gorka within the final stage of the Late Pleistocene – Early Holocene between 13900-10500 cal BP. [ABSTRACT FROM AUTHOR]

This paper discusses various aspects of the use of wood for crafts in the Middle Ages, based on xylological analyses of 4211 crafted items of everyday use discovered at 62 archaeological sites in Poland. Over 1500 items were identified in the authors’ own analyses, and the remaining taxonomic data were taken from the literature. The research showed that the main types of wood used at the time were Pinus sylvestris, Quercus sp., Fraxinus excelsior, Picea sp. vel Larix sp., Taxus baccata, Alnus sp., Abies alba and Euonymus sp. Nineteen other taxa were used to make a much smaller pool of objects. At most of the analysed sites a similar set of materials was used to produce the items, regardless of their age and location. The choice of wood was selective and was based on the characteristics of particular tree and shrub species. Large coopered vessels were primarily made of wood from Quercus sp., Pinus sylvestris and Taxus baccata. The manufacture of turned utensils usually involved Fraxinus excelsior, while stave bowls were made using only Pinus sylvestris and Picea/Larix (mainly Picea abies). To verify the local availability of the source taxa, we used pollen sequences from natural and anthropogenic sites in the vicinity of the places where the examined artefacts were found. The choice of wood was limited by the availability of the trees and shrubs. In north-western Poland the most important taxa used for woodworking in the Middle Ages were Pinus sylvestris, Quercus sp., Fraxinus excelsior and Fagus sylvatica; in the south, Picea/Larix and Abies alba were used most frequently. Some items made of Abies alba, Picea and Larix were imported from other parts of the country. We inferred two stages of the use of wood by medieval Polish craftsmen. In the first stage, from the mid-10th century to the late 12th century, they largely used deciduous taxa; the second stage, from the 13th to the 15th centuries, saw the increased use of conifers. We found that the medieval craftsmen chose high-quality wood without defects. Radial wood with the best technical parameters was preferred. Its share increased in the late Middle Ages; this can be attributed to the craftsmen’s increasing familiarity with carpentry techniques.

Quantitative reconstructions of past climates are an important resource for evaluating how well climate models reproduce climate changes. One widely used statistical approach for making such reconstructions from fossil biotic assemblages is weighted averaging partial least-squares regression (WA-PLS). There is however a known tendency for WA-PLS to yield reconstructions compressed towards the centre of the climate range used for calibration, potentially biasing the reconstructed past climates. We present an improvement of WA-PLS by assuming that: (i) the theoretical abundance of each taxon is unimodal with respect to the climate variable considered; (ii) observed taxon abundances follow a multinomial distribution in which the total abundance of a sample is climatically uninformative; and (iii) the estimate of the climate value at a given site and time makes the observation most probable, i.e. it maximizes the log-likelihood function. This climate estimate is approximated by weighting taxon abundances in WA-PLS by the inverse square of their climate tolerances. We further improve the approach by considering the frequency (fx) of the climate variable in the training dataset. Tolerance-weighted WA-PLS with fx correction greatly reduces the compression bias, compared with WA-PLS, and improves model performance in reconstructions based on an extensive modern pollen dataset. [ABSTRACT FROM AUTHOR]

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Quantitative reconstruction of past plant abundance from fossil pollen data is still a challenging task for palynologists. During the last decades, mechanistic methods have been developed to convert pollen assemblages from peat and lake deposits into vegetation abundance at regional and local scale. Coastal areas are particularly sensitive to climate and environmental hazards. Thus, quantitative estimates of past vegetation are important to better understand their history and address potential effects of future environmental changes. However, assumptions of the mechanistic models of pollen dispersal and deposition originally designed for near-circular lakes and bogs located inland are violated when applied to coastal sites because of different basin shape and wind direction distribution. This study investigates how to adapt a model of pollen dispersal and deposition developed for lakes to coastal lagoons. A new geometry is defined, and it is demonstrated how some of the major formulas from previous models can be used without any modification in this singular context. [ABSTRACT FROM AUTHOR]

Highlights • A temporal-spatial vegetation variation since the LGM in China was mapped. • Relative to today, forest expanded northwards by 2–5° by warm early and mid-Holocene. • Inverse vegetation model was used to study the dominant factors for paleovegetation. • The dominant factors differ between Holocene and the last glacial periods. Abstract The need to reduce the uncertainty of predictions of vegetation change under global warming highlights the importance of understanding the vegetation patterns and possible mechanisms of vegetation response during past warming intervals. Here, we present quantitative regional vegetation reconstructions for China during the Last Glacial Maximum (LGM, 18 ± 2 14C kyr B.P.), early Holocene (EH, 8.5 ± 0.5 14C kyr B.P.), and mid-Holocene (MH, 6 ± 0.5 14C kyr B.P.), using the biomization method and based on 249 pollen records. In addition, we used an inverse vegetation modeling approach to investigate the effect of climate change and CO 2 concentration on the observed vegetation changes. The results demonstrate that during the LGM, steppe expanded southeastwards, reaching the present-day temperate deciduous forest (TEDE) zone; in contrast, the forest in eastern China underwent a substantial southward retreat and its percentage reached a minimum. The warm mixed forest (WAMF) and TEDE shifted southwards of ∼10° N relative to today, and tropical seasonal rain forest (TSFO) was almost absent. In addition, the forest-steppe boundary shifted southwards to near the middle and lower reaches of the Yangtze River. During the EH and MH, the TSFO, WAMF, and TEDE exhibited respective northward shifts of 2°, 4° and 5° relative to today. In MH, the percentage of forest sites increased and reached a maximum, and the forest-steppe boundary had shifted northwestwards to near the present-day 300 mm isohyet. Our palaeovegetation reconstructions and model sensitivity experiments suggest that temperature was the dominant factor controlling the vegetation distribution during the LGM, while precipitation became increasingly more important during the Holocene throughout China. We further show that precipitation was the primary factor controlling palaeovegetation distribution in northern China, while temperature became increasingly more important in southern China. Our findings are potentially important for understanding the evolution of vegetation in China in response to ongoing global warming. [ABSTRACT FROM AUTHOR]

This paper discusses various aspects of the use of wood for crafts in the Middle Ages, based on xylological analyses of 4211 crafted items of everyday use discovered at 62 archaeological sites in Poland. Over 1500 items were identified in the authors' own analyses, and the remaining taxonomic data were taken from the literature. The research showed that the main types of wood used at the time were Pinus sylvestris, Quercus sp., Fraxinus excelsior, Picea sp. vel Larix sp., Taxus baccata, Alnus sp., Abies alba and Euonymus sp. Nineteen other taxa were used to make a much smaller pool of objects. At most of the analysed sites a similar set of materials was used to produce the items, regardless of their age and location. The choice of wood was selective and was based on the characteristics of particular tree and shrub species. Large coopered vessels were primarily made of wood from Quercus sp., Pinus sylvestris and Taxus baccata. The manufacture of turned utensils usually involved Fraxinus excelsior, while stave bowls were made using only Pinus sylvestris and Picea/Larix (mainly Picea abies). To verify the local availability of the source taxa, we used pollen sequences from natural and anthropogenic sites in the vicinity of the places where the examined artefacts were found. The choice of wood was limited by the availability of the trees and shrubs. In north-western Poland the most important taxa used for woodworking in the Middle Ages were Pinus sylvestris, Quercus sp., Fraxinus excelsior and Fagus sylvatica, in the south, Picea/Larix and Abies alba were used most frequently. Some items made of Abies alba, Picea and Larix were imported from other parts of the country. We inferred two stages of the use of wood by medieval Polish craftsmen. In the first stage, from the mid-10th century to the late 12th century, they largely used deciduous taxa, the second stage, from the 13th to the 15th centuries, saw the increased use of conifers. We found that the medieval craftsmen chose high-quality wood without defects. Radial wood with the best technical parameters was preferred. Its share increased in the late Middle Ages, this can be attributed to the craftsmen's increasing familiarity with carpentry techniques. [ABSTRACT FROM AUTHOR]

Characterization of land cover change in the past is fundamental to understand the evolution and present state of the Earth system, the amount of carbon and nutrient stocks in terrestrial ecosystems, and the role played by land-atmosphere interactions in influencing climate. The estimation of land cover changes using palynology is a mature field, as thousands of sites in Europe have been investigated over the last century. Nonetheless, a quantitative land cover reconstruction at a continental scale has been largely missing. Here, we present a series of maps detailing the evolution of European forest cover during last 12,000 years. Our reconstructions are based on the Modern Analog Technique (MAT): a calibration dataset is built by coupling modern pollen samples with the corresponding satellite-based forest-cover data. Fossil reconstructions are then performed by assigning to every fossil sample the average forest cover of its closest modern analogs. The occurrence of fossil pollen assemblages with no counterparts in modern vegetation represents a known limit of analog-based methods. To lessen the influence of no-analog situations, pollen taxa were converted into plant functional types prior to running the MAT algorithm. We then interpolate site-specific reconstructions for each timeslice using a four-dimensional gridding procedure to create continuous gridded maps at a continental scale. The performance of the MAT is compared against methodologically independent forest-cover reconstructions produced using the REVEALS method. MAT and REVEALS estimates are most of the time in good agreement at a trend level, yet MAT regularly underestimates the occurrence of densely forested situations, requiring the application of a bias correction procedure. The calibrated MAT-based maps draw a coherent picture of the establishment of forests in Europe in the Early Holocene with the greatest forest-cover fractions reconstructed between ∼8,500 and 6,000 calibrated years BP. This forest maximum is followed by a general decline in all parts of the continent, likely as a result of anthropogenic deforestation. The continuous spatial and temporal nature of our reconstruction, its continental coverage, and gridded format make it suitable for climate, hydrological, and biogeochemical modeling, among other uses.

Carpinus betulus L. is a mesic, usually considered late-successional tree widely distributed in Europe, but almost absent from Iberia, where it is generally assumed that disappeared during the coldest stages of the Würm. High-resolution pollen analyses were carried out in 14C dated sediments from a drowned estuary (ria) and a small mountain lake. Carpinus pollen identification was confirmed by comparative light and scanning electron microscopy. Hornbeam dynamics are interpreted using palaeoclimatic reconstructions based on independent proxies (diatoms, chironomids and dinocysts). Our results support that hornbeam declined between ca. 60,000 and ca. 9,000 cal yr BP, when multiproxy evidence suggests a major regional relative sea-level rise. Moreover, chironomid-inferred July temperatures show an increase of more than 6 °C between 15,600 and 10,500 cal yr BP, while freshwater aquatics and diatoms indicate a general tendency towards increasing precipitation and a more oceanic climate. Carpinus survived during the Würm in a variety of habitats in coastal valleys in NW Iberia which had adequate climatic and edaphic conditions. Such habitats might be comparable to the oak-ash, ravine, and hardwood floodplain forests currently existing in other regions of Europe. Large areas of these coastal ecosystems disappeared at the onset of the Holocene, when the sea-level rose. Later hornbeam was apparently unable to compete and expand further inland. Therefore, the sea-level rise combined with the climatically-induced Holocene tree succession and the increasing human impact during the Mid and Late Holocene led to hornbeam progressively becoming a marginal tree in the area. [ABSTRACT FROM AUTHOR]

Characterization of land cover change in the past is fundamental to understand the evolution and present state of the Earth system, the amount of carbon and nutrient stocks in terrestrial ecosystems, and the role played by land-atmosphere interactions in influencing climate. The estimation of land cover changes using palynology is a mature field, as thousands of sites in Europe have been investigated over the last century. Nonetheless, a quantitative land cover reconstruction at a continental scale has been largely missing. Here, we present a series of maps detailing the evolution of European forest cover during last 12,000 years. Our reconstructions are based on the Modern Analog Technique (MAT): a calibration dataset is built by coupling modern pollen samples with the corresponding satellite-based forest-cover data. Fossil reconstructions are then performed by assigning to every fossil sample the average forest cover of its closest modern analogs. The occurrence of fossil pollen assemblages with no counterparts in modern vegetation represents a known limit of analog-based methods. To lessen the influence of no-analog situations, pollen taxa were converted into plant functional types prior to running the MAT algorithm. We then interpolate site-specific reconstructions for each timeslice using a four-dimensional gridding procedure to create continuous gridded maps at a continental scale. The performance of the MAT is compared against methodologically independent forest-cover reconstructions produced using the REVEALS method. MAT and REVEALS estimates are most of the time in good agreement at a trend level, yet MAT regularly underestimates the occurrence of densely forested situations, requiring the application of a bias correction procedure. The calibrated MAT-based maps draw a coherent picture of the establishment of forests in Europe in the Early Holocene with the greatest forest-cover fractions reconstructed between ~8,500 and 6,000 calibrated years BP. This forest maximum is followed by a general decline in all parts of the continent, likely as a result of anthropogenic deforestation. The continuous spatial and temporal nature of our reconstruction, its continental coverage, and gridded format make it suitable for climate, hydrological, and biogeochemical modeling, among other uses. [ABSTRACT FROM AUTHOR]

Our understanding on the spatial-temporal patterns of climatic variability over the last few millennia in the East Asian monsoon-dominated northern China (NC), and its role at a macro-scale in affecting the prosperity and depression of Chinese dynasties is limited. Quantitative high-resolution, regionally-synthesized palaeoclimatic reconstructions as well as simulations, and numerical analyses of their relationships with various fine-scale, numerical agro-ecological, social-economic, and geo-political historical records during the period of China's history, are presented here for NC. We utilize pollen data together with climate modeling to reconstruct and simulate decadal- to centennial-scale variations in precipitation or temperature for NC during the last 2200 years (-200–2000 AD). We find an overall cyclic-pattern (wet/warm or dry/cold) in the precipitation and temperature anomalies on centennial- to millennial-scale that can be likely considered as a representative for the entire NC by comparison with other related climatic records. We suggest that solar activity may play a key role in driving the climatic fluctuations in NC during the last 22 centuries, with its quasi ∼100, 50, 23, or 22-year periodicity clearly identified in our climatic reconstructions. We employ variation partitioning and redundancy analysis to quantify the independent effects of climatic factors on accounting for the total variation of 17 fine-grained numerical Chinese historical records. We quantitatively illustrate that precipitation (67.4%) may have been more important than temperature (32.5%) in causing the overall agro-ecological and macro-geopolitical shifts in imperial China with NC as the central ruling region and an agricultural heartland over the last 2200 years. [ABSTRACT FROM AUTHOR]

Pollen information as such is highly valuable and was considered so far as a self-evident good free for the public. The foundation for reliable and serious pollen information is the careful, scientific evaluation of pollen content in the air. However, it is essential to state and define now the requirements for pollen data and qualifications needed for institutions working with pollen data in the light of technical developments such as automated pollen counting and various political interests in aerobiology including attempts to finally acknowledge pollen and spores as relevant biological particles in the air worth being considered for pollution and health directives. It has to be emphasized that inadequate pollen forecasts are a considerable health risk for pollen allergy sufferers. Therefore, the responsibility of institutions involved in pollen monitoring and forecasting is high and should be substantiated with respective qualifications and know-how. We suggest here for the first time a portfolio of quality criteria and demand rigorous scientific monitoring and certification of such institutions in the interest and for the protection of persons affected by a pollen allergy. [ABSTRACT FROM AUTHOR]

To better understand the long-term changes of the East Asian summer monsoon precipitation (Pjja), quantitative reconstructions and model simulations are needed. Here, we develop continental-scale pollen-based transfer functions for Pjja with weighted averaging–partial least squares (WA-PLS) regression and a Bayesian multinomial regression method. We apply these transfer functions to a set of fossil pollen data from monsoonal China for quantitatively reconstructing the Pjja changes over the last 9500 years. We compare the reconstructions with Pjja simulations from a coupled atmosphere–ocean–sea ice general circulation model (the Kiel Climate Model, KCM). The results of cross-validation tests for the transfer functions show that both the WA-PLS model (r2 = 0.83, root mean square error of prediction (RMSEP) = 112.11 mm) and the Bayesian model (r2 = 0.86, RMSEP = 107.67 mm) exhibit good predictive performance. We stack all Pjja reconstructions from northern China to a summary curve. The stacked record reveals that Pjja increased since 9500 cal. yr BP, attained its highest level during the Holocene summer monsoon maximum (HSMM) at ~7000–4000 cal. yr BP and declined to present. The KCM output and the reconstructions differ in the early-Holocene (~9500–7000 cal. yr BP) where the model suggests higher Pjja than the reconstructions. Moreover, during the HSMM, the amplitude of the Pjja changes (~20–60 mm above present) in simulations is lower than the reconstructed changes (~70–110 mm above present). The rising (declining) Pjja patterns in reconstructions before (after) the HSMM are more pronounced and fluctuating than in simulations. Other palaeohydrological data such as lake-level reconstructions indicate substantial monsoon precipitation changes throughout the Holocene. Our results therefore show that the KCM underestimates the overall amplitude of the Holocene monsoon precipitation changes. [ABSTRACT FROM AUTHOR]

In this paper we test the performance of the Regional Estimates of VEgetation Abundance from Large Sites (REVEALS) model using pollen records from multiple small sites. We use Holocene pollen records from large and small sites in southern Sweden to identify what is/are the most significant variable(s) affecting the REVEALS-based reconstructions, i.e. type of site (lakes and/or bogs), number of sites, site size, site location in relation to vegetation zones, and/or distance between small sites and large sites. To achieve this objective we grouped the small sites according to (i) the two major modern vegetation zones of the study region, and (ii) the distance between the small sites and large lakes, i.e. small sites within 50, 100, 150, or 200 km of the large lakes. The REVEALS-based reconstructions were performed using 24 pollen taxa. Redundancy analysis was performed on the results from all REVEALS-model runs using the groups within (i) and (ii) separately, and on the results from all runs using the groups within (ii) together. The explanatory power and significance of the variables were identified using forward selection and Monte Carlo permutation tests. The results show that (a) although the REVEALS model was designed for pollen data from large lakes, it also performs well with pollen data from multiple small sites in reconstructing the percentage cover of groups of plant taxa (e.g. open land taxa, summer-green trees, evergreen trees) or individual plant taxa; however, in the case of this study area, the reconstruction of the percentage cover of Calluna vulgaris, Cyperaceae, and Betula may be problematic when using small bogs; (b) standard errors of multiple small-site REVEALS estimates will generally be larger than those obtained using pollen records from large lakes, and they will decrease with increasing size of pollen counts and increasing number of small sites; (c) small lakes are better to use than small bogs if the total number of small sites is low; and (d) the size of small sites and the distance between them do not play a major role, but the distance between the small sites and landscape/vegetation boundaries is a determinant factor for the accuracy of the vegetation reconstructions. [ABSTRACT FROM AUTHOR]

Information on how species distributions and ecosystem services are impacted by anthropogenic climate change is important for adaptation planning. Palaeo data suggest that Abies alba formed forests under significantly warmer-than-present conditions in Europe and might be a native substitute for widespread drought-sensitive temperate and boreal tree species such as beech ( Fagus sylvatica) and spruce ( Picea abies) under future global warming conditions. Here, we combine pollen and macrofossil data, modern observations, and results from transient simulations with the LPX-Bern dynamic global vegetation model to assess past and future distributions of A. alba in Europe. LPX-Bern is forced with climate anomalies from a run over the past 21 000 years with the Community Earth System Model, modern climatology, and with 21st-century multimodel ensemble results for the high-emission RCP8.5 and the stringent mitigation RCP2.6 pathway. The simulated distribution for present climate encompasses the modern range of A. alba, with the model exceeding the present distribution in north-western and southern Europe. Mid-Holocene pollen data and model results agree for southern Europe, suggesting that at present, human impacts suppress the distribution in southern Europe. Pollen and model results both show range expansion starting during the Bølling-Allerød warm period, interrupted by the Younger Dryas cold, and resuming during the Holocene. The distribution of A. alba expands to the north-east in all future scenarios, whereas the potential (currently unrealized) range would be substantially reduced in southern Europe under RCP8.5. A. alba maintains its current range in central Europe despite competition by other thermophilous tree species. Our combined palaeoecological and model evidence suggest that A. alba may ensure important ecosystem services including stand and slope stability, infrastructure protection, and carbon sequestration under significantly warmer-than-present conditions in central Europe. [ABSTRACT FROM AUTHOR]

Quantitative estimates of past vegetation with a clearly defined spatial scale are a critical step to better understand the patterns and processes of changes in vegetation and land-cover over time and space. However, such estimates are difficult to obtain from pollen data due to their lack of spatial dimension and the inter-taxonomic differences in pollen production, dispersal, and deposition mechanisms. This study assesses the potential of the Landscape Reconstruction Algorithm (LRA) to reconstruct the spatial and temporal patterns of upland vegetation in the Bassiès Valley, northern Pyrenees over the last 200 years, a period characterised by a decline of traditional pastoral activities. We used well-dated pollen records from eight bogs and ponds and vegetation and land-cover data within a 1-km radius from each site to evaluate the LRA-based reconstruction of local land-cover. The LRA approach was then used to reconstruct the 200-year history of local land-cover dynamics at 10 to 20-year intervals around each site in relation to land-abandonment. Our study shows that in addition to allowing long-term reconstruction, LRA estimates (1) are more sensitive to vegetation composition changes over time and space compared to historical land-cover maps and pollen percentages, and (2) improve the reconstruction of past local vegetation compared to pollen percentages alone. The LRA results reveal site-specific land-cover trajectories within the small-sized study area over 200 years. Some sites exhibit changes in land-cover composition with heathland and tree cover increase (ESC, EM), while others are found to be more stable, dominated 1) exclusively by heathland (LEG, W1652), 2) heathland with intermediate proportions of grassland (FOUZ, SIG), or 3) exclusively by grassland (OT). This land-cover composition variability over space and time may be related both to local topography and past grazing activity. The quantification of past vegetation dynamics provides opportunities for bridging the gap between researchers, policy makers and practitioners, and should be taken into account to further investigate the effect of long-term grazing activities on the past and modern plant and landscape diversity. • Landscape Reconstruction Algorithm (LRA) estimates of mountain land-cover changes over 200 years. • LRA estimates are more sensitive to vegetation changes compared to historical land-cover maps and pollen percentages. • LRA estimates revealed site-specific land-cover trajectories within the study area. • Some sites show increase in woody land-covers, others have more stable trajectories with different dominant types. • Spatio-temporal variability of land-cover composition may be related to past grazing activity. [ABSTRACT FROM AUTHOR]

This paper presents vegetation and climate reconstructions for the forest zone in the central part of the East European Plain, Russia, for the time period 10,000–7900 cal. BP. Reconstructions were based on pollen records from three key regions located in taiga, mixed coniferous-broadleaved and broadleaved forest zones. Results showed that the considered period was characterized by relatively low air temperatures and high precipitation compared with modern conditions. Analysis of the long-term pattern of the mean annual temperature for all three regions reveal two synchronous significant cooling periods observed 9300–9100 cal. BP and 8500–8100 cal. BP as well as rapid growth of the air temperature in 8100–7800 cal. BP, when the annual temperatures increased by 3 °C during about 300 years. The cooling phase of 8500–8100 cal. BP could correspond to the distinct “8.2 ka event” widely recorded across Europe. Periods of climate warming are coincided with periods of precipitation rise whereas the cool phases are characterized by its decrease. The ratio of actual evapotranspiration and precipitation amount selected as indicator of surface moistening conditions decreased significantly in period of cooling phases (down to 0.27) and can be used as a clear indicator of ground surface overwatering and strengthening of mire formation processes. [ABSTRACT FROM AUTHOR]

Question How do pollen-based functional and phylogenetic diversity help to explain post-glacial vegetation change in relation to climate and human influence? Location Estonia and Latvia, NE Europe. Methods We used a data set of 1062 pollen samples from 20 sites covering the last 14 500 yrs to estimate plant richness, evenness, functional and phylogenetic diversity (community-weighted mean and mean pair-wise distance). We adjusted existing functional and phylogenetic diversity measures for the pollen data and tested the methods with a simulation study. The simulations showed that species-based and pollen-based diversity estimates were all significantly positively correlated. Results The Late Glacial (14 500-11 650 cal. yr BP) and the mid-Holocene (8000-4000 cal. yr BP) periods showed contrasting values for most of the diversity components, and several diversity estimates were strongly associated with climate. The cold climate during the Late Glacial led to high phylogenetic diversity, and relatively low functional diversity. Climate warming during the transition from the Late Glacial to the Holocene was followed by a decrease in phylogenetic diversity but an increase in functional diversity based on plant height and seed weight. Increasing human impact in the late Holocene was associated with an increase in plant richness and decreases in functional diversity based on plant height and seed weight and in phylogenetic diversity of herbs. Conclusions Pollen-based functional and phylogenetic diversity provide novel insights into post-glacial vegetation change and its drivers. Both functional and phylogenetic diversity were closely related to climatic conditions, suggesting that trait differences play an important role in long-term community response to climate change. Our results indicate that human impact during the last two millennia has influenced functional and phylogenetic diversity negatively by suppressing plants with certain traits (functional convergence) and giving advantage to plants from certain phylogenetic lineages. We see great potential in the further development of functional and phylogenetic diversity methods for pollen data. [ABSTRACT FROM AUTHOR]

Houjiayao Relic Site in Nihewan Basin plays a significant role in the Paleolithic culture of China and in the stages of Paleolithic human evolution. Previous studies have primarily concentrated on ancient human and mammal fossils and their chronostratigraphy. Studies on the relevance of paleoclimate and paleoenvironment for the survivals of ancient mankind in Houjiayao Relic Site are limited, and we are unaware of any quantitative investigation of this topic. In this paper, we use pollen data from 420 surface sample sites and 83 fossil pollen data, and apply the MAT (Modern Analogue Technique) method to quantitatively reconstruct the sequences of annual average temperature and annual average precipitation in the area of Houjiayao Relic Site. The sequences of the climate change quantitatively reconstructed based on the pollen data have a relatively good correspondence with MIS5, MIS6 and MIS7. The annual average temperature in the Nihewan Basin during the glacial period was approximately 3–4 °C less than the present, and the annual average precipitation was approximately 200–400 mm greater than the present. The annual average temperature during the inter-glacial period was approximately 1 °C higher than the present, or it was close to the current value, and the annual average precipitation was also similar to the current value. The paleoclimate in Nihewan Basin was relatively stable in the glacial period, and frequently fluctuated during the inter-glacial period. Houjiayao Man lived in the Dali glacial period (MIS6), and animals and plants were the main source of food. Houjiayao Man had learned to adapt to and withstand the cold climate. [ABSTRACT FROM AUTHOR]

We present quantitative reconstructions of regional vegetation cover in north-western Europe, western Europe north of the Alps, and eastern Europe for five time windows in the Holocene [around 6k, 3k, 0.5k, 0.2k, and 0.05k calendar years before present ( bp)] at a 1° × 1° spatial scale with the objective of producing vegetation descriptions suitable for climate modelling. The REVEALS model was applied on 636 pollen records from lakes and bogs to reconstruct the past cover of 25 plant taxa grouped into 10 plant-functional types and three land-cover types [evergreen trees, summer-green (deciduous) trees, and open land]. The model corrects for some of the biases in pollen percentages by using pollen productivity estimates and fall speeds of pollen, and by applying simple but robust models of pollen dispersal and deposition. The emerging patterns of tree migration and deforestation between 6k bp and modern time in the REVEALS estimates agree with our general understanding of the vegetation history of Europe based on pollen percentages. However, the degree of anthropogenic deforestation (i.e. cover of cultivated and grazing land) at 3k, 0.5k, and 0.2k bp is significantly higher than deduced from pollen percentages. This is also the case at 6k in some parts of Europe, in particular Britain and Ireland. Furthermore, the relationship between summer-green and evergreen trees, and between individual tree taxa, differs significantly when expressed as pollen percentages or as REVEALS estimates of tree cover. For instance, when Pinus is dominant over Picea as pollen percentages, Picea is dominant over Pinus as REVEALS estimates. These differences play a major role in the reconstruction of European landscapes and for the study of land cover-climate interactions, biodiversity and human resources. [ABSTRACT FROM AUTHOR]

Off-site pollen data as well as onsite plant macrofossil data from Southwest Germany enable the distinguishing of three main phases of agricultural land use history. The last phase, here simplified called the 'Extensive ard phase', had already started in the Bronze Age and ends in the 19th century a.d. It is characterized by extensive land management, permanent fields with short fallow phases, ploughing, the use of animal dung as fertilizer, and grazed woodlands. The first phase, comprising the Old and Middle Neolithic, is characterized by hoe-farming only on very fertile soils and a very restricted set of crops. For the second phase, comprising the Young, Late and Final Neolithic, a slash-and-burn-like agricultural system is most probable. During the Late and Final Neolithic, this cultivation system with fire use and shifting fields was gradually practised on permanent fields and was modified, leading finally to the 'Extensive ard' land use system with fertilizer and ploughing instead of burning. [ABSTRACT FROM AUTHOR]

This paper presents an assessment of Holocene tree cover densities and forest disturbance in European Russia using the best-modern-analogue (BMA) technique of quantitative reconstruction and an innovative approach, which combines modern pollen datasets with remotely sensed data from moderate-resolution imaging spectroradiometer satellite images. The test of the accuracy of the applied method using a database of 450 sets of surface pollen assemblages shows that it can reproduce present day characteristics of woody cover in Europe correctly ( R = 0.57, standard error = 10.8 %), and it is sufficient for reconstruction of major changes of woodland vegetation in the past. Application of the BMA technique to fossil pollen data from two key regions in the central part of European Russia demonstrates that changes in regional woody cover are useful for the reconstruction of prehistoric human disturbance. [ABSTRACT FROM AUTHOR]