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1. Sedimentary pollen offers excellent opportunities to reconstruct vegetation changes over past millennia. Number of different pollen taxa or pollen richness is used to characterise past plant richness. To improve the interpretation of sedimentary pollen richness, it is essential to understand the relationship between pollen and plant richness in contemporary landscapes. This study presents a regionalscale comparison of pollen and plant richness from northern Europe and evaluates the importance of environmental variables on pollen and plant richness. 2. We use a pollen dataset of 511 lake-surface pollen samples ranging through temperate, boreal and tundra biomes. To characterise plant diversity, we use a dataset formulated from the two largest plant atlases available in Europe. We compare pollen and plant richness estimates in different groups of taxa (wind-pollinated vs. non-wind-pollinated, trees and shrubs vs. herbs and grasses) and test their relationships with climate and landscape variables. 3. Pollen richness is significantly positively correlated with plant richness (r = 0.53). The pollen plant richness correlation improves (r = 0.63) when high pollen producers are downweighted prior to estimating richness minimising the influence of pollen production on the pollen richness estimate. This suggests that methods accommodating pollen-production differences in richness estimates deserve further attention and should become more widely used in Quaternary pollen diversity studies. 4. The highest correlations are found between pollen and plant richness of trees and shrubs (r = 0.83) and of wind-pollinated taxa (r = 0.75) suggesting that these are the best measures of broad-scale plant richness over several thousands of square kilometres. 5. Mean annual temperature is the strongest predictor of both pollen and plant richness. Landscape openness is positively associated with pollen richness but not with plant richness. Pollen richness values from extremely open and/or cold areas where pollen production is low should be interpreted with caution because low local pollen production increases the proportion of extra-regional pollen. 6. Synthesis. Our results confirm that pollen data can provide insights into past plant richness changes in northern Europe, and with careful consideration of pollen-production differences and spatial scale represented, pollen data make it possible to investigate vegetation diversity trends over long time-scales and under changing climatic and habitat conditions.

Fossil pollen data can provide important information of past vegetation diversity, on the basis of established relationship between modern palynological and floristic diversity. However, current studies on modern pollen assemblages in China have not examined this relationship yet. Herein, we report a case study from Northeast China, aiming to investigate the representation of modern palynological diversity to regional floristic diversity. A total of 87 sets of modern pollen and vegetation data from various vegetation types were applied to assess modern palynological diversity and floristic diversity in Northeast China, and the relationship between palynological and floristic diversity was studied using spatial pattern comparison and correlation analysis. Moreover, to reduce representation bias related to pollen production and dispersal, we calibrated pollen data using the Regional Estimates of Vegetation Abundance from Large Sites (REVEALS) model with Pollen Productivity Estimates (PPEs) and Fall Speeds of Pollen (FSP). The results show that the spatial variations of palynological and floristic richness among vegetation types are similar, and have a good positive correlation ( r =0.41, p <0.01). However, palynological evenness presents a different spatial pattern from floristic evenness, with a weaker positive correlation ( r =0.21, p >0.05). The calibration on pollen data using REVEALS model minimized the differences in spatial patterns between palynological and floristic diversity, and improved the correlations between them (richness, r =0.50, p <0.01; evenness, r =0.33, p <0.01). Our study indicates that palynological richness in Northeast China could reflect regional floristic richness in general, and the calibration with REVEALS model is recommended for reconstructing past floristic diversity from pollen data.

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.

Aim: We used fossil records to explore patterns of change in vegetation composition, turnover and diversity along an elevational gradient during the late-glacial to early Holocene, and to locate the elevations most sensitive to past climate changes. Location: Romania. Methods: Changes in the late-glacial vegetation communities were inferred from seven published pollen records distributed within the main vegetation belts of the Romanian Carpathians, at elevations from 275 to 1840 m. Principal components analysis, detrended canonical correspondence analysis (DCCA) and rarefaction analysis were undertaken on these data. Results: DCCA indicates that compositional change is strongest (SD 1.2, c. 70%) at the late-glacial/Holocene transition (c, 11,500 cal. yr BP), but significant shifts also occur at c. 14,700, c. 13,800 and c. 12,700 cal. yr BP (SD 0.4-0.8, 25-50%). Palynological turnover is greater for mid-elevation records (730-1100 m) than at low and high elevations. Intervals of greater palynological richness occur between c. 13,800 and 12,500 cal. yr BP and after 11,500 cal. yr BP, and intervals of lower richness occur before c. 14,000 cal. yr BP and between c. 12,900 and 11,500 cal. yr BP. Main conclusions: Variations in species composition during repeated climate changes of the late-glacial suggest that community composition at a given time was not only a result of the environmental conditions of that period, but also the legacy of previous cumulative recruitment and extirpation events. Turnover estimates suggest that mid-elevations have been the most sensitive to climate change during the late-glacial and early Holocene. Palynological richness estimates show a less clear elevational pattern and no evidence for a greater sensitivity of this measure of biodiversity at high elevations to past climate change. However, results may have been affected by taxa with high pollen productivity and distance dispersability. Our finding concurs with other palaeoecological and local-scale modelling studies in suggesting that small populations have survived in favourable microhabitats embedded within larger unsuitable areas during the late-glacial, features not captured by broad-scale model predictions.

1. Past changes in plant and landscape diversity can be evaluated through pollen analysis, however, pollen-based diversity indexes are potentially biased by differential pollen production and deposition. Studies examining the relationship between pollen and landscape diversity are therefore needed. The aim of this study was to evaluate how different pollen-based indexes capture aspects of landscape diversity. 2. Pollen counts were obtained from surface samples of 50 small- to medium-sized lakes in Brandenburg (north-east Germany) and compiled into two sets, with one containing all pollen counts from terrestrial plants and the second restricted to wind-pollinated taxa. Both sets were adjusted for the pollen production/dispersal bias using the REVEALS model. A high-resolution biotope map was used to extract the density of total biotopes and different biotopes per area as parameters describing landscape diversity. In addition, tree species diversity was obtained from forest inventory data. 3. The Shannon index and the number of taxa in a sample of 10 pollen grains are highly correlated and provide a useful measure of pollen type diversity which corresponds best to landscape diversity within one km of the lake and the proportion of non-forested area within seven km. Adjustments of the pollen production/dispersal bias only slightly improve the relationships between pollen diversity and landscape diversity for the restricted data set as well as for the forest inventory data and corresponding pollen types. 4. Using rarefaction analysis, we propose the following convention: pollen type diversity is represented by the number of types in a small sample (low count e.g. 10), pollen type richness is the number of types in a large sample (high count e.g. 500), and pollen sample evenness is characterized by the ratio of the two. 5. Synthesis. Pollen type diversity is a robust index that captures vegetation structure and landscape diversity. It is ideally suited for between site comparisons as it does not require high pollen counts. In concert with pollen type richness and evenness, it helps evaluating the effect of climate change and human land use on vegetation structure on long timescales.

In intensive farmland habitats, pollination of wild flowers and crops may be threatened by the widespread decline of pollinators. The honey bee decline, in particular, appears to result from the combination of multiple stresses, including diseases, pathogens, and pesticides. The reduction of semi-natural habitats is also suspected to entail floral resource scarcity for bees. Yet, the seasonal dynamics and composition of the honey bee diet remains poorly documented to date. In this study, we studied the seasonal contribution of mass-flowering crops (rapeseed and sunflower) vs. other floral resources, as well as the influence of nutritional quality and landscape composition on pollen diet composition over five consecutive years. From April to October, the mass of pollen and nectar collected by honey bees followed a bimodal seasonal trend, marked by a two-month period of low food supply between the two oilseed crop mass-flowerings (ending in May for rapeseed and July for sunflower). Bees collected nectar mainly from crops while pollen came from a wide diversity of herbaceous and woody plant species in semi-natural habitats or from weeds in crops. Weed species constituted the bulk of the honey bee diet between the mass flowering crop periods (up to 40%) and are therefore suspected to play a critical role at this time period. The pollen diet composition was related to the nutritional value of the collected pollen and by the local landscape composition. Our study highlights (1) a food supply depletion period of both pollen and nectar resources during late spring, contemporaneously with the demographic peak of honey bee populations, (2) a high botanical richness of pollen diet, mostly proceeding from trees and weeds, and (3) a pollen diet composition influenced by the local landscape composition. Our results therefore support the Agri-Environmental Schemes intended to promote honey bees and beekeeping sustainability through the enhancement of flower availability in agricultural landscapes.

Aim: We investigate the response of vegetation composition and plant diversity to increasing land clearance, burning and agriculture at the Mesolithic—Neolithic transition (c. 6400—5000 BC) when first farming was introduced. Location: The Valais, a dry alpine valley in Switzerland. Methods: We combine high-resolution pollen, microscopic charcoal and sedimentological data to reconstruct past vegetation, fire and land use. Pollen evenness, rarefaction-based and accumulation-based palynological richness analyses were used to reconstruct past trends in plant diversity. Results: Our results show that from c. 5500 cal. yr BC, slash-and-burn activities created a more open landscape for agriculture, at the expense of Pinus and Betula forests. Land clearance by slash-and-burn promoted diverse grassland ecosystems, while on the long term it reduced woodland and forest diversity, affecting important tree species such as Ulmus and Tilia. Main conclusions: Understanding the resilience of Alpine ecosystems to past disturbance variability is relevant for future nature conservation plans. Our study suggests that forecasted land abandonment in the Alps will lead to pre-Neolithic conditions, with significant biodiversity losses in abandoned grassland ecosystems. Thus, management measures for biodiversity, such as ecological compensation areas, are needed in agricultural landscapes with a millennial history of human impact, such as the non-boreal European lowlands. Our study supports the hypothesis that species coexistence is maximized at an intermediate level of disturbances. For instance, species richness decreased when fire exceeded the quasi-natural variability observed during the Mesolithic times. Under a more natural disturbance regime, rather closed Pinus sylvestris and mixed oak forests would prevail.

Understanding the significance of pollen diversity is key to reconstructing plant diversity over long timescales. Here we present quantitative pollen-plant diversity comparisons for a mountainous area of the Western Mediterranean region. Samples were collected between 430–1,865 m elevation and pollen-plant diversity assessed through richness and turnover (beta-diversity) metrics. We found statistically significant relationships between pollen diversity metrics and the diversity of pollen-equivalent plant taxa in the surrounding vegetation. The strongest richness relationships emerged from the exclusion of trees and with standardisation of the sample size (rarefaction) applied to both plant and pollen datasets. Three different metrics for turnover produced similar results, but emphasise different components of beta diversity (replacement vs richness differences). These results pave the way for reconstructing biodiversity trends from pollen sequences, with a number of caveats. Fossil pollen is a potentially rich source of information on past biodiversity in the Mediterranean region.

We performed lithogeochemical and biostratigraphical studies of the core from the hole 8182 in the Northern paleovalley of Vitim Plateau. According to lithogeochemical characteristics of the sediments in the section, 5 members were found out. Three lower ones characterize the Dzhilinda suite, two upper ones – the Khoygot stratum. The analysis of biodiversity and fossil diatom algae distribution in the core resulted in revealing of 137 species and varieties of diatom algae related to 50 genera. Four diatom zones (DZ) were established by appearing or disappearing of index species. Ecological and geographic analysis showed domination of planktonic, indifferent, cosmopolite species. Palynological analysis revealed three pollen members with reconstruction of vegetation of forest type reflecting the vector of cooling and climate change from moderately warm one in Middle-Late Miocene to moderately cool in Early Pliocene.

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.