Pollen Data Research Articles

The role of dispersal limitation in the forest biome shifts of Europe in the last 18,000 years

AbstractAimHow the ability of plants to move towards newly favourable habitats (dispersal limitation) impacts the change of biome distribution and transition under fast climate warming is still debated. Analysing vegetation change in the past may help to clarify the relative importance of underlying ecological processes such as climate, biotic interactions, and dispersal. In this study, we investigated how dispersal limitation affected the distribution of European forests in the last 18,000 years.LocationSouthern and Central Europe.TaxonSpermatophyta.MethodsUsing the LPJ‐GM 2.0 model (an extension of LPJ‐GUESS), we simulated European vegetation from the end of the Last Glacial Maximum (18.5 ka) to the current time (0 ka). Using biome reconstructions from pollen data as reference, we compared the performance of two dispersal modes: with no migration constraints or seed limitation (free dispersal mode), and with plant establishment depending on seed dynamics and dispersal (dispersal limitation mode).ResultsThe model run, including migration processes, was better at capturing the post‐glacial expansion of European temperate forests (and the longer persistence of boreal forests) than the setting assuming free dispersal, especially during periods of rapid warming. This suggests that a number of (temperate) tree taxa experienced delayed occupancy of climatically suitable habitats due to a limited dispersal capacity, i.e., post‐glacial migration lags.Main ConclusionsOur results show that including migration processes in model simulations allows for more realistic reconstructions of forest patterns under rapid climate change, with consequences for future projections of carbon sequestration and climate reconstructions with vegetation feedback, assisted migration and forest conservation.

LOVE Is in the R—Two R Tools for Local Vegetation Reconstruction

Pollen deposition in small lakes and peatlands is composed of local pollen deposition arriving from the nearby vegetation and of regional pollen deposition arriving from farther away. The LOVE model aims to reconstruct past vegetation on a small local scale by extracting only the local pollen signal. To this end, pollen deposition from small sites is related to pollen deposition from large lakes with predominantly regional pollen deposition. We here present a new implementation of the LOVE model in the R environment for statistical computing that is more user friendly than existing implementations. It allows more readily application with fossil pollen data and facilitates extensive testing of the approach in simulated landscapes. The LOVE model derives from critical mathematical assumptions that strongly limit its application. We additionally present LOVEoptim as an adjusted approach to local-scale reconstructions. Other than in LOVE, past local plant abundances are approximated using numerical optimization. Tests in a simulated landscape, which is based on true landscape patterns from digital maps, show that both approaches are valid. Due to fewer mathematical assumptions, LOVEoptim is more widely applicable. The modeling results help to better interpret the spatial scale of vegetation reflected in LOVE/LOVEoptim reconstructions.

Greening a lost world: Paleoartistic investigations of the early Pleistocene vegetation landscape in the first Europeans' homeland

The scarcity of pictorial reconstructions focusing on Quaternary flora and vegetation prompts a reevaluation of traditional zoocentrism in future paleoartistic research. Here we present paleoartistic renderings depicting vegetation landscapes around the Orce Archaeological Zone (OAZ), encompassing sites dating from 1.6 to 1.2 million years ago during the Early Pleistocene of the Guadix-Baza Basin in southern Spain. Four pieces are based on fossil pollen data from Venta Micena 1 (VM1), Barranco León (BL), and Fuente Nueva 3 (FN3). The artwork considers altitudinal belt distribution, taxonomic and structural diversity, extinct taxa in the Iberian Peninsula post-Early Pleistocene, and those previously extinct at higher latitudes in Europe. This essay visually represents the coexistence of mesophytic, thermophytic, and xerophytic plant communities within a glacial refugium of woody species. Lastly, employing a non-conventional iconographic approach, we portray a female Homo individual in the forest refugium to draw up on possible adaptive traits of these early Europeans.

Vegetation diversity in response to monsoonal variability in the Eastern Himalaya, India over the past ~13 000 yrs

Monsoon precipitation plays a crucial role in shaping the diversity of vegetation in the Himalayas, both in terms of temporal and spatial distribution. While palynology has traditionally been employed to reconstruct the past climate of the Himalaya, there has been limited understanding of how monsoon-related changes affect the structure and distribution of vegetation. To address this, we analysed pollen data from a 3 m deep sedimentary profile in the higher Sikkim Himalaya to reconstruct monsoon driven changes in vegetation diversity. Our results show a highly fluctuating trend of pollen and diversity parameters at late-Pleistocene-Holocene transition for which fluctuating hydroclimatic conditions and differential pollen preservation in coarser sediments is attributed. During the Early Holocene (10,438–7934 cal yrs BP) favourable hydroclimatic conditions led to a rapid expansion of mixed broad-leaved forests, marked by higher values of richness and alpha diversity. Between 7934 and 5481 cal yrs BP, the region experienced moderate hydroclimatic conditions that facilitated expansion and diversification of woody taxa, and correlated with the global Holocene Climate Optimum (HCO). Conversely, from 5481 to3949 cal yrs BP, declining total pollen count (TPC), species richness, and alpha diversity indicates significant shifts in vegetation composition under deteriorating climatic conditions, which corresponds with the 4.2 ka event worldwide. From 3949 to 2049 cal yrs BP, an increasing yet variable trend in TPC and diversity indices, suggests warm-humid conditions prevailed in the region. During the last 1086 cal yrs, an increasing trend is recorded in the palyno assemblage and diversity parameters suggesting ameliorating climate, matches well with the Mediaeval Climate Anomaly (MCA). Our inferences suggest that the palyno assemblage and diversity parameters are quiet sensitive to warm and humid conditions.

Quadrat soil pollen signal reflects plant important values in forests and shrublands from subtropical China.

Pollen analysis, a crucial tool in botany and ecology for examining historical biotic dynamics, has elicited debate owing to its complex link with vegetation. The challenge lies in discerning the ecological significance of pollen data. In this study, we conducted detailed quadrat surveys on Jinhua Mountain, subtropical China, analyzing topsoil pollen to determine whether pollen signals accurately reflect key ecological components in the forests and shrublands. We performed direct comparisons between pollen and plant compositions and calculated pollen percentages and plant Important Values (IVs) for each quadrat. The results indicate greater homogeneity in pollen composition across the study area compared to plant composition, particularly in the high percentage of Pinus pollen. However, distinct plant communities exhibited significantly different pollen compositions, as evidenced by the multi-response permutation test. This divergence aligns with variations in the dominant plant species across different communities. There were significant correlations between pollen percentages and plant IVs, with correlation coefficients of 0.55 (p < 0.001) at the quadrat level and 0.78 (p < 0.001) at the taxon level. These results support the utility of pollen analysis for representing ecologically significant values in subtropical Chinese forests and shrublands. Such correlations might also be extrapolated to pollen-based paleoecological studies.

Pollen morphology of Rosales from Brazilian forest fragments of Cerrado

ABSTRACT Rosales, a well-supported order of angiosperms encompassing heterogeneous plants, holds significant representation in Brazilian territory, particularly Cerrado regions. These areas are susceptible to human impact. In this context, pollen data is vital in supporting taxonomic and ecological studies for species preservation. We analyzed pollen grains from 15 native Rosales species found in Brazilian Cerrado forest fragments belonging to the Cannabaceae, Moraceae, Rhamnaceae, and Rosaceae families using light and scanning electron microscopy. The pollen grains underwent acetolysis, qualitative description, and measurements, with statistical analysis, including multivariate methods, applied to quantitative data. Qualitative findings were organized for pollen description and multivariate cluster analysis. Our observations revealed pollen grains in monads, isopolar, small to medium, with subcircular, circular, or subtriangular amb, and suboblate, oblate-spheroidal, or prolate-spheroidal. Apertures include 2–3-porate, 3-colpate, or 3-colporate, with long or short ectoapertures, lalongate or circular endoapertures. The exine is thin, microreticulate, psilate-perforate, microgranulate, nanoechinate, or striate ornamentation, with the sexine thicker than the nexine. The key characteristics distinguishing families are number, type of apertures, and exine ornamentation. Quantitative data (length and width of ectoapertures, equatorial diameter in polar view, and polar diameter in equatorial view) contribute to the understanding of the palynology of Rosales from forest fragments, as these characteristics allow us to identify species or groups of species. Our findings confirm Rosales as eurypalinous, while the genera analyzed demonstrate stenopalynous traits. The qualitative and quantitative characteristics of pollen identified here expand the morphological knowledge of the species and can be used to understand the relationship among them.

Landscapes of risk: A comparative analysis of landscape metrics for the ecotoxicological assessment of pesticide risk to bees

Abstract Pesticide use in agricultural landscapes creates environmental contamination that is heterogenous in space and time. Mobile organisms, such as bees, are exposed to multiple contamination sources when visiting patches that vary in the amount, timing and toxicity of pesticides used. Yet, environmental risk assessments (ERA) typically fail to consider this heterogeneity, in part because of the complexities of estimating exposure to different pesticides, and subsequent risk at organism‐relevant scales. We use pesticide assays of 269 bee‐collected pollen samples to understand the spatiotemporal variability of risk across a network of 41 field sites in southern Sweden. Observed bee pesticide risk is calculated based on compound‐specific residue quantifications in pollen and standardized toxicity data. We then compare the ability of three classes of landscape‐scale variables to predict this risk: (1) landscape composition and configuration metrics, (2) landscape load based on national pesticide use data and (3) predictions from a newly developed bee pesticide exposure model. Based on use data, 10 crops account for 81% of the total risk. We detected 49 pesticide compounds in bee‐collected pollen. Although herbicides and fungicides constitute the bulk of detected pesticides, both in frequency and amount quantified, unsurprisingly, insecticides contribute the most to risk. Landscape composition and configuration metrics did not predict observed pesticide risk, and interactions with bee species indicate taxa‐dependency in predictions. Landscape load predicted observed risk consistently between taxa. Risk estimates from our exposure model were strongly predictive but only when considering realized risk (i.e., risk estimates based on prior pesticide use information). Synthesis and applications. Predicting pesticide risk based on landscape patterns could enable landscape‐scale ERA. However, simple metrics of landscape pattern, such as proportion of agricultural land, are not sufficient. We found that risk observed in bee‐collected pollen was best predicted when integrating spatialized pesticide use in the pesticide exposure model, underscoring the importance of such data for research, monitoring and mitigation. Further, we propose a guidance framework for future landscape ecotoxicological risk analyses that clarifies data needs relative to risk prediction goals.

Hydroclimatic changes in eastern China during the Holocene based on pollen data and climate modeling

The Asian monsoon system represents one of the world's most dynamic interactions of the cryosphere-continent-ocean-atmosphere system. Understanding and responding to changes in monsoonal precipitation is a major component of environmental management in this region, given its profound influence on socioeconomic activity in monsoonal Asia. In particular, characterizing the spatiotemporal variability of the East Asian summer monsoon (EASM) is critical for comprehensively understanding its dynamics and future impacts. Although substantial progress has been made in reconstructing past changes in the EASM, the spatial pattern of EASM intensity in China on the orbital-scale remains controversial. This is mainly because of uncertainties in the climatic interpretation of EASM-related proxies. Here, we present a quantitative seasonal precipitation reconstruction for monsoonal China during the Holocene, using the Modern Analog Technique (MAT) based on pollen data. The results show that during the Holocene both the annual and summer precipitation in monsoonal China increased gradually and reached a peak during the early mid-Holocene, with respective values that were ∼ 170 mm and 60 mm higher than today, followed by a decrease in the late Holocene. On the regional scale, the temporal pattern of monsoon rainfall was discrepant: a decrease from the early through late Holocene in northern China, and an increase from the early through late Holocene in southern China.To investigate the possible forcing mechanisms of these phenomena, we used the full TraCE-21 k simulation and single-forcing transient simulations to analyze spatial and temporal rainfall patterns. The results suggest that the north-south pattern is the product of orbital forcing. Intensified summer insolation during the early Holocene enhanced the land-sea thermal contrast, which strengthened the EASM along with the northward extension of the west Pacific subtropical high. Both factors caused the increased withdrawal of oceanic water vapor and the northward advance of the EASM rain belt, delivering more rainfall to northern China and less rainfall to southern China, and vice versa. Overall, our results indicate that insolation variations were the dominant factor determining the spatial pattern of EASM precipitation during the Holocene. Our findings are relevant to the calibration of palaeoclimate models and they contribute to an improved understanding of the Asian monsoon sub-systems.

Quantitative Holocene climate reconstruction and anthropogenic impact analysis based on the pollen records in peat sediment in Southern China

The quantitative reconstruction of Holocene paleoclimate is pivotal for unraveling the evolution of East Asian Monsoon (EAM). Some recent studies have highlighted the escalating human activities in the late Holocene, which could potentially pose significant challenges to the precise quantitative reconstruction of paleoclimate. In this study, we undertake a quantitative reconstruction of Holocene climate and human influence index (HII) based on pollen data from the Shiwangutian (SWGT) in Southern China. This is achieved by developing and applying a pollen-based calibration model utilizing Locally Weighted Average-Partial Least Squares Regression (LWWA-PLS) and the Modern Analogue Technique (MAT). Our findings reveal that evergreen forests experienced expansion between 11.6 and 9.0 cal ka BP, coinciding with elevated Mean Annual Precipitation (Map) and Mean Annual Temperature (Mat) levels. These patterns signify a progressively warm and wet climate during this period. Subsequently, evergreen forests achieved their maximum abundance between 9.0 and 4.0 cal ka BP, aligning with a notable increase in vegetation richness, indicating a warmer and wetter climate during the mid-Holocene. Notably, during the interval of 6.0–4.0 cal ka BP, the Map, Mat, and Precipitation of Warmest Month (Mpwa) reached the Holocene optimum, approximately 14% higher than modern. Consequently, we deduce that in the early and middle Holocene, when the monsoon was particularly strong, synchronous changes in precipitation fostered the regional expansion of evergreen broad-leaved forests. Furthermore, the record demonstrates a substantial reduction in forest cover and a noteworthy increase in the HII value since 4.0 cal ka BP, likely attributable to anthropogenic impacts. Our analysis suggests that the influence of anthropogenic activities surpassed that of natural climate factors in shaping regional vegetation cover. These findings offer insights into potential drivers of climate change. As a preliminary conclusion, we propose that the summer insolation, ice sheets, and meltwater fluxes were the primary controlling factors for climate variations during the early to mid-Holocene in Southern China.

Re‐investigation of the Bispingen palaeolake sediment succession (northern Germany) reveals that the Last Interglacial (Eemian) in northern‐central Europe lasted at least ~15 000 years

Investigating past interglacial climatic and environmental changes can enhance our understanding of the natural rates and ranges of climate variability under interglacial boundary conditions. However, comparing past interglacial palaeoclimate records from different regions and archives is often complicated by differing and uncertain chronologies. For instance, the duration of the Last Interglacial in Europe is still controversial as southern European palaeoclimate records suggest a duration of ~16 500–18 000 years, while a length of only ~11 000 years in northern‐central Europe was previously inferred from the analysis of partly annually laminated (varved) palaeolake sediments recovered at Bispingen, northern Germany. To resolve this discrepancy, we here present sediment microfacies, geochemistry and pollen data from a new sediment core from the Bispingen palaeolake sediment succession, covering the entire Last Interglacial (Eemian) and the earliest part of the Last Glacial (Weichselian). In particular, we provide evidence that the duration of the Last Interglacial at Bispingen must have been hitherto underestimated due to the investigation of an incomplete sediment core. Using microscopic varve counting and sedimentation rate estimates for non‐varved sections on the new sediment core, we show that the Eemian in northern‐central Europe probably lasted at least ~15 000 years, about 4000 years longer than previously thought. This new duration estimate is in much better agreement with results from southern European palaeoclimate records, clarifying the enigma of a steep trans‐European vegetation gradient for several millennia at the end of the Last Interglacial.

Vegetation Patterns during the Last 132,000 Years: A Synthesis from Twelve Eifel Maar Sediment Cores (Germany): The ELSA-23-Pollen-Stack

Seven published and four new pollen records from well-dated sediment cores from six Pleistocene and Holocene maar structures located in the Eifel, Germany, are combined to a pollen stack that covers the entire last 132,000 years. This stack is complemented by new macroremain data from one additional sediment core. The pollen data included into the stack show consistently that the Eifel was covered by a dense forest during the Eemian, early Marine Isotope Stage (MIS) 3, and the Holocene. While other European records indeed indicate a warming, the early MIS 3 fully developed forest remains a unique feature in central European pollen records. Comparison to orbital parameters and insolation hints to warm and humid, however, not fully interglacial conditions, which are also visible in speleothem growth throughout Europe. With the cooling trend towards the glacial maxima of MIS 4 and 2, tree pollen declined, with recovering phases during MIS 5c and 5a, as well as during all MIS 3 interglacials. During the colder stadials, steppe vegetation expanded. For MIS 5 and 4, we defined six new landscape evolution zones based on pollen and macroremains.

Predicting the main pollen season of Broussonetia Papyrifera (paper mulberry) tree.

Paper mulberry pollen, declared a pest in several countries including Pakistan, can trigger severe allergies and cause asthma attacks. We aimed to develop an algorithm that could accurately predict high pollen days to underpin an alert system that would allow patients to take timely precautionary measures. We developed and validated two prediction models that take historical pollen and weather data as their input to predict the start date and peak date of the pollen season in Islamabad, the capital city of Pakistan. The first model is based on linear regression and the second one is based on phenological modelling. We tested our models on an original and comprehensive dataset from Islamabad. The mean absolute errors (MAEs) for the start day are 2.3 and 3.7 days for the linear and phenological models, respectively, while for the peak day, the MAEs are 3.3 and 4.0 days, respectively. These encouraging results could be used in a website or app to notify patients and healthcare providers to start preparing for the paper mulberry pollen season. Timely action could reduce the burden of symptoms, mitigate the risk of acute attacks and potentially prevent deaths due to acute pollen-induced allergy.

EUPollMap: the European atlas of contemporary pollen distribution maps derived from an integrated Kriging interpolation approach

Abstract. Modern and fossil pollen data are widely used in paleoenvironmental research to characterize past environmental changes in a given location. However, their discrete and discontinuous nature can limit the inferences that can be made from them. Deriving continuous spatial maps of the pollen presence from point-based datasets would enable more robust regional characterization of such past changes. To address this problem, we propose a comprehensive collection of European pollen presence maps including 194 pollen taxa derived from the interpolation of pollen data from the Eurasian Modern Pollen Database (EMPD v2) restricted to the Euro-Mediterranean Basin. To do so, we developed an automatic Kriging-based interpolation workflow to select an optimal geostatistical model describing the spatial variability for each taxon. The output of the interpolation model consists of a series of multivariate predictive maps of Europe at 25 km scale, showing the occurrence probability of pollen taxa, the predicted presence based on diverse probability thresholds, and the interpolation uncertainty for each taxon. Combined visual inspections of the maps and systematic cross-validation tests demonstrated that the ensemble of predictions is reliable even in data-scarce regions, with a relatively low uncertainty, and robust to complex and non-stationary pollen distributions. The maps, freely distributed as GeoTIFF files (https://doi.org/10.5281/zenodo.10015695, Oriani et al., 2023), are proposed as a ready-to-use tool for spatial paleoenvironmental characterization. Since the interpolation model only uses the coordinates of the observation to spatialize the data, the model can also be employed with fossil pollen records (or other presence/absence indicators), thus enabling the spatial characterization of past changes, and possibly their subsequent use for quantitative paleoclimate reconstructions.

Modern pollen dispersal in relation to present vegetation distribution and land use in the Baspa valley, Kinnaur, western Himalayas.

Interpretation of a fossil pollen data for the vegetation and climate reconstruction of any region needs a modern pollen-vegetation analogue for its calibration. We analyzed the surface sediments and moss polsters for the pollen and microcharcoal records to understand the modern pollen-vegetation relationship and human activities in the Baspa Valley, Kinnaur, Himachal Pradesh. Presently, valley is occupied by the arboreal and non-arboreal vegetation of temperate to subalpine habitats and land use activities. The recovered pollen assemblages showed variability in the dispersal behavior of pollen of taxa growing along the valley transect and also captured the signals of human activities over land use. The overall dominance of arboreal pollen in the recovered pollen assemblage corresponds with the dominant growth of conifers and broadleaf tree taxa and represents the valley vegetation at a regional scale. However, the profuse pollen production of a few arboreal taxa and long distance pollen transport from one vegetation zone to other by the strong upthermic valley winds could bias the pollen representation of in-situ vegetation. The high pollen frequency of non-arboreal taxa in the open meadows represents the near vicinity to their plant source. Human activities like fire burning and cultivation by the local population are evident by the recovery of microcharcoal particles and pollen of plants belonging to Cerealia Poaceae, Asteraceae, Amaranthaceae, Polygonaceae, Rosaceae, Juglandaceae, etc. The dataset taken as modern pollen-vegetation analogue is useful to assess past changes in the vegetation and land cover in relation to climate and human factors for future sustenance.

Assessment of environmental risk areas based on airborne pollen patterns as a response to land use and land cover distribution

Allergic respiratory diseases are considered to be among the most important public health concerns, and pollen is the main cause of allergic respiratory diseases worldwide. However, the biological component of air quality is largely underestimated, and there is an important gap in the legislation in this area. The aims of this study were to characterise the occurrence and incidence of pollen exposure in relation to potential pollen sources and to delineate the main areas of aerobiological risk in the Madrid Autonomous Region based on homogeneous patterns of pollen exposure. This study uses the historical aerobiological database of the Madrid Region Palynological Network (central Spain) from ten pollen stations from 1994 to 2022, and the land-use information from the Corine Land Cover. Multiple clustering approaches were followed to group the sampling stations and subsequently all the 1 × 1km pixels for the Madrid Autonomous Region. The clustering dendrogram for land-use distribution was compared to the dendrogram for historical airborne pollen data. The two dendrograms showed a good alignment with a very high correlation (0.95) and very low entanglement (0.15), which indicates a close correspondence between the distribution of the potential pollen sources and the airborne pollen dynamics. Based on this knowledge, the Madrid Autonomous Region was divided into six aerobiological risk areas following a clear anthropogenic gradient in terms of the potential pollen sources that determine pollen exposure in the Madrid Region. Spatial regionalisation is a common practice in environmental risk assessment to improve the application of management plans and optimise the air quality monitoring networks. The risk areas proposed by scientific criteria in the Madrid Autonomous Region can be adjusted to other operational criteria following a framework equivalent to other air quality networks.

A modern pollen dataset from lake surface sediments on the central and western Tibetan Plateau

Abstract. Modern pollen datasets are essential for pollen-based quantitative paleoclimate (e.g. precipitation) reconstructions, which can aid in better understanding recent climate change and its underlying forcing mechanisms. A modern pollen dataset based on surface sediments from 90 lakes in the shrub, meadow, steppe and desert regions of the central and western Tibetan Plateau (TP) was established to fill geographical gaps left by previous datasets. Ordination analyses of pollen data and climatic parameters revealed that annual precipitation is the dominant factor in modern pollen distribution on the central and western TP. A regional transfer function for annual precipitation was developed with weighted averaging partial least squares (WA-PLS), which suggests a good inference power of the modern pollen dataset for annual precipitation. A case study in which the transfer function was effectively applied to a fossil pollen record from Tangra Yumco on the central TP for paleoprecipitation reconstruction demonstrated the significance of the modern pollen dataset in a lower data region for paleoclimate change studies. Data from this study, including pollen data for each sample and information on the sampled sites (location, altitude and climate data), are openly available via the Zenodo portal (https://doi.org/10.5281/zenodo.8008474, Ma et al., 2023).

Revealing early Neolithic vegetation and environmental changes in the Lower Yangtze Valley, eastern China: Pollen insights

The Lower Yangtze Valley, a key region in understanding early Neolithic human activities, presents an unsolved question regarding the early occurrence of such impact before 8.0 cal ka BP. The elusive details around the specific time and the environmental background underscore the need for more investigation. In addition, regional vegetation is obscurely known in this region mainly attributed to variable pollen sources resulting from highly unstable deposition environment in this widespread marine-flood interaction plains. This paper reconstructs the vegetation-environmental history in the Lower Yangtze Valley during 10.1–7.2 cal ka BP and identifies regional forests and potential signals of human activities through analyses of AMS 14C dates, pollen data, and grain size. The results show that during the period from 10,100 to 8270 cal a BP, a stable deciduous oak forest as the regional forest dominated the region in a monotonous vegetation pattern. After 8270 cal a BP, deciduous oak trees receded, while evergreen oak trees and other woody types expanded, resulting in the regional vegetation transitioning to a regional mixed evergreen-deciduous broad-leaved forest up to 7230 cal a BP. Moreover, early indications of human activity were detected by high abundance of Poaceae including rice (Oryza sativa) type. Together with a previously reported rice phytolith record from neighboring areas, this research provides compelling pollen evidence suggesting that human activities in the Lower Yangtze Valley likely at least dated back to 8200 cal a BP, around 2000 years earlier than current archeological records.

Kettle-hole peatlands as carbon hot spots: Unveiling controls of carbon accumulation rates during the last two millennia

Understanding carbon sequestration patterns in time and space is crucial for models and future projections of carbon uptake. However, their past provides an insight to this understanding, and peatlands play an essential role in the carbon cycle. Hence, peat carbon accumulation rates (PCAR) were reconstructed for the last ±1500 years in three Polish kettle-hole peatlands (Jaczno, Głęboczek and Pawski Ług bogs). Absolute chronologies, retrieved from the Bayesian age-depth models based on high-resolution 14C AMS dating, provided good time control, whereas the selected time interval spanned a broad spectrum of environmental changes and human activity. An additional variable was connected to climate, as the chosen sites are situated along the west-east gradient of northern Poland.The aim was to find factors responsible for changes in carbon accumulation, so the results of PCAR were combined with pollen, testate amoebae, plant macrofossil, and charcoal data. The research showed that the investigated peatlands varied regarding local environmental conditions (e.g. water level), peatland development, vegetation changes, and fire activity. Generally, the PCAR values were higher in the Sphagnum-dominated sections of the profiles with high shares of mixotrophic testate amoebae unless fire hampered the carbon sequestration. However, our research showed that the changes in carbon uptake resulted from various overlapping factors rather than just one. Nevertheless, high values of PCAR in Jaczno and Pawski Ług (mean 74.6 and 79.64 g C/m2/yr, respectively) point to kettle-hole peatlands being exceptionally efficient in carbon sequestration.

Non-pollen palynomorph assemblages in mid- to late Holocene wetland deposits and their palaeoenvironments of deposition: Microfossil signatures in sediment sequences of the Yangtze Delta coastal lowlands, East China

Fluvial processes such as sediment deposition within drainage channels and seasonal overbank flooding, and fluvial events such as occasional high intensity floods all leave particular sedimentary signatures in terms of their lithology and also in their contained microfossil assemblages, which represent different environments of deposition. Over several thousand years the Yangtze River in eastern China has developed a coastal lowland plain around its delta that is mainly composed of stacked fluvial sediment facies, but also includes many marine or estuarine layers in some areas, as well as deposits of limnic and semi-terrestrial pool, marsh and mire origin, some of which are highly organic. The fluvial facies are dominantly clastic sequences of sands, silts and clays that reflect a range of deposition from quiet water to high energy conditions and in varying water depths, mainly governed by fluvial input from the Yangtze and the many other, smaller, rivers and streams of the deltaic lowland. The limnic and marshland sediments reflect autochthonous deposition in a range of freshwater wetland types of varying water depth, from lake through marsh/fen to surface peatland. Allied to lithological and pollen data, non-pollen palynomorph spore assemblages and abundances within these complex sedimentary sequences, particularly from algal communities, provide signatures of floodplain wetland depositional history and hydrodynamic patterns. We have used groupings of these microfossil data to characterise the sedimentary facies of the lower Yangtze coastal plain and to reconstruct hydrological history across the area at a range of spatial scales. Fluctuations in the relative taxa abundances are good indicators of changes in water levels at the site scale from surface waterlogging through reedswamp and fen to deeper open water. While some changes seem to be site specific, the data show flooding and increased water depths that correlate with known phases of climatic deterioration.

Reconstruction of paleoecological and paleofire dynamics of the Tobol areas based on materials from lake-swamp deposits of Oskino

The paper compares palaeoecological, archaeological and palaeo-fire data from lake-swamp deposits of the Tobol river region, obtained as a result of the study of the Oskino wetland lake. The dependence of palaeofire dynamics on human economic activity and climate-induced changes in plant communities is analysed. The reconstruction covers 9.6 ka, including the entire period of occupation of the area, as well as the end of the Greenlandian stage and the beginning of the Northgrippian stage. Comparison of pollen data, concentration of macroscopic charcoal particles in lake-swamp sediments showed a correlation between decreasing moisture levels, increasing conifer proportion in forest composition and increasing fire frequency. It has been established on the vegetation anthropogenic influence was little (pollen data) partly due to this is related to the orientation population towards an appropriative type of economy up to 4.5 ka BP. The palynological data not show significant changes in the residential landscape or an increase in the frequency of fires in connection with the emergence of livestock breeding in the Late Bronze Age. In the Early Iron Age, semi-nomadic livestock breeding was formed the population probably did not need to burn forests for grazing, so the intensity of fires did not increase.