Natural and Human-Transformed Vegetation and Landscape Reflected by Modern Pollen Data in the Boreonemoral Zone of Northeastern Europe

Modern pollen composition obtained from waterbody surface sediment represents surrounding vegetation and landscape features. A lack of detailed information on modern pollen from Latvia potentially limits the strength of various pollen-based reconstructions (vegetation composition, climate, landscape, human impact) for this territory. The aim of this study is to compare how modern pollen from natural and human-made waterbodies reflects the actual vegetation composition and landscape characteristics. Modern pollen analyses from surface sediment samples of 36 waterbodies from Latvia alongside oceanic-continental, lowland-upland, urban-rural and forested-agricultural gradients have been studied. In addition, we considered the dominant Quaternary sediment, soil type and land use around the studied waterbodies in buffer zones with widths of one and four km. The information on climate for the last 30 years from the closest meteorological station for each study site was obtained. Data were analyzed using Pearson correlation and principal component analysis. Results show that relative pollen values from surface sediment of waterbodies reflect dominant vegetation type and land use. Modern forest biomass had a positive correlation with pollen accumulation rate, indicating the potential use of pollen-based forest biomass reconstructions for the boreonemoral zone after additional research and calibration.Peer reviewe

Airborne birch pollen in Poland and Latvia in the light of data obtained from aerobiological monitoring and tauber traps in relation to mean air temperature

Birch pollen contains allergens belonging to those with the strongest allergenic properties. In order to trace pollen season patterns of this taxon and pollen annual sums at a wider regional scale, cooperation was established with the University of Latvia in Riga (Latvia). A comparison of the results obtained in the years 2003-2008 in Lublin and in Riga, using volumetric samplers, shows that there was a similar trend in the abundance of birch pollen. The highest sums were noted at both sites in 2003. In all the study years, more birch pollen grains were recorded in Lublin than in Riga, on the average by 7110. The birch pollen seasons started earlier in Lublin than in Riga, on the average by 6 days, and they ended earlier in Lublin, on the average by 18 days. In Riga the birch pollen seasons were longer and less abundant than in Lublin. In addition, in both the regions, i.e. in SE Poland (the Roztocze area) and in Latvia (the area of Marupe near Riga, Taurene, Teici and Rucava), there is pollen data series available obtained from annual pollen deposition monitoring conducted using the modified Tauber traps. These pollen counts have been carried out under the Pollen Monitoring Programme (http://pmp.oulu.fi) since 1998. The 11- year data series in Roztocze and the 10-year data series in Latvia allowed the trends in the occurrence of years of abundant or poor birch pollen release to be traced. In Roztocze maximum Betula pollen deposition occurred in the year 2003, in Latvia - in 1999. The absence of a significant correlation between SE Poland and Latvia with regard to the trends in the occurrence of years of abundant Betula pollen deposition induced the authors to seek climatic factors responsible for increased birch pollen production. The analysis of the Spearman's rank correlation coefficients between annual Betula pollen sums in Roztocze and mean air temperature in June, July and August in the year preceding pollen emission as well as in spring (January-April) of the year of pollen emission showed a statistically significant negative correlation with air temperature in February of the year of pollen emission

Patterns in recent and Holocene pollen accumulation rates across Europe - the Pollen Monitoring Programme Database as a tool for vegetation reconstruction

The collection of modern, spatially extensive pollen data is important for the interpretation of fossil pollen assemblages and the reconstruction of past vegetation communities in space and time. Modern datasets are readily available for percentage data but lacking for pollen accumulation rates (PARs). Filling this gap has been the motivation of the pollen monitoring network, whose contributors monitored pollen deposition in modified Tauber traps for several years or decades across Europe. Here we present this monitoring dataset consisting of 351 trap locations with a total of 2742 annual samples covering the period from 1981 to 2017. This dataset shows that total PAR is influenced by forest cover and climate parameters, which determine pollen productivity and correlate with latitude. Treeless vegetation produced PAR values of at least 140 grains cm−2 yr−1. Tree PAR increased by at least 400 grains cm−2 yr−1 with each 10 % increase in forest cover. Pollen traps situated beyond 200 km of the distribution of a given tree species still collect occasional pollen grains of that species. The threshold of this long-distance transport differs for individual species and is generally below 60 grains cm−2 yr−1. Comparisons between modern and fossil PAR from the same regions show similar values. For temperate taxa, modern analogues for fossil PARs are generally found downslope or southward of the fossil sites. While we do not find modern situations comparable to fossil PAR values of some taxa (e.g. Corylus), CO2 fertilization and land use may cause high modern PARs that are not documented in the fossil record. The modern data are now publicly available in the Neotoma Paleoecology Database and aid interpretations of fossil PAR data.publishedVersio

Patterns in recent and Holocene pollen accumulation rates across Europe - the Pollen Monitoring Programme Database as a tool for vegetation reconstruction

The collection of modern, spatially extensive pollen data is important for the interpretation of fossil pollen assemblages and the reconstruction of past vegetation communities in space and time. Modern datasets are readily available for percentage data but lacking for pollen accumulation rates (PARs). Filling this gap has been the motivation of the pollen monitoring network, whose contributors monitored pollen deposition in modified Tauber traps for several years or decades across Europe. Here we present this monitoring dataset consisting of 351 trap locations with a total of 2742 annual samples covering the period from 1981 to 2017. This dataset shows that total PAR is influenced by forest cover and climate parameters, which determine pollen productivity and correlate with latitude. Treeless vegetation produced PAR values of at least 140 grains cm(-2) yr(-1). Tree PAR increased by at least 400 grains cm(-2) yr(-1) with each 10% increase in forest cover. Pollen traps situated beyond 200 km of the distribution of a given tree species still collect occasional pollen grains of that species. The threshold of this long-distance transport differs for individual species and is generally below 60 grains cm(-2) yr(-1). Comparisons between modern and fossil PAR from the same regions show similar values. For temperate taxa, modern analogues for fossil PARs are generally found downslope or southward of the fossil sites. While we do not find modern situations comparable to fossil PAR values of some taxa (e.g. Corylus), CO2 fertilization and land use may cause high modern PARs that are not documented in the fossil record. The modern data are now publicly available in the Neotoma Paleoecology Database and aid interpretations of fossil PAR data

Occurence of Ragweed Plants and Pollen in Latvia

Ragweed poses a health and an agricultural risk that need to be assessed in Latvia by determining the growth of ragweed plants and pollen transported from local sources and neighboring countries. It has been stated that the northern border for the growth of ragweed exists at the 55o latitude north and Latvia is situated between the 55 and 58° latitude north. This study investigates the collection of ragweed plants during field studies of other plants (1970- 2007) and pollen collected from aerobiological monitoring in Riga starting from 2003. Ragweed is classified as an invasive plant species and was found growing alongside main transportation routes (railways and roads) in Latvia. The most harmful species, A. artemisiifolia, represented 84% of all the ragweed plants, followed by 9% of A. trifida and 5% of A. psilostachya. Field studies in 2007 that located ragweed were repeated, but no plants were found in the same locations in 2011. Herbariums have revealed that ragweed plants have flowered between the middle of July until September. Aerobiological studies have revealed ragweed pollen during the day within a two weeks period between late August and the start of September that suggests pollen from local sources. The pollen concentration only reached a concentration of 2-3 grains/m3 over the two weeks period starting in August. Ragweed pollen is presently not a threat in Latvia, but more studies need to be conducted to follow any changes over time

Natural and Human-Transformed Vegetation and Landscape Reflected by Modern Pollen Data in the Boreonemoral Zone of Northeastern Europe

Modern pollen composition obtained from waterbody surface sediment represents surrounding vegetation and landscape features. A lack of detailed information on modern pollen from Latvia potentially limits the strength of various pollen-based reconstructions (vegetation composition, climate, landscape, human impact) for this territory. The aim of this study is to compare how modern pollen from natural and human-made waterbodies reflects the actual vegetation composition and landscape characteristics. Modern pollen analyses from surface sediment samples of 36 waterbodies from Latvia alongside oceanic-continental, lowland-upland, urban-rural and forested-agricultural gradients have been studied. In addition, we considered the dominant Quaternary sediment, soil type and land use around the studied waterbodies in buffer zones with widths of one and four km. The information on climate for the last 30 years from the closest meteorological station for each study site was obtained. Data were analyzed using Pearson correlation and principal component analysis. Results show that relative pollen values from surface sediment of waterbodies reflect dominant vegetation type and land use. Modern forest biomass had a positive correlation with pollen accumulation rate, indicating the potential use of pollen-based forest biomass reconstructions for the boreonemoral zone after additional research and calibration

Indicative value and training set of freshwater organic-walled algal palynomorphs (non-pollen palynomorphs)

Only a few studies have related modern non-pollen palynomorphs to environmental variables, limiting the development of non-pollen palynomorphs training sets. Here, we perform substantial groundwork by developing a training set for freshwater organic-walled algal palynomorphs. We sampled surface sediments from 78 waterbodies across Latvia in north-eastern Europe with the aim of gaining infor-mation on the distribution and diversity of algal palynomorphs. We analysed the preferred living con-ditions (water and sediment properties) of algal palynomorphs in conjunction with climate and catchment characteristics (Quaternary sediment type, landscape usage, and composition). In total, 94 species/taxa belonging to four phyla (Cyanobacteria, Chlorophyta, Charophyta, and Ochrophyta) were identified. By applying statistical and descriptive analyses, we showed the indicative value of algal palynomorphs along various gradients. Using the established training set, we for the first constructed organic-walled algal palynomorphs-based pH and electric conductivity reconstructions for two lakes where natural and anthropogenic variability was recognised. Freshwater algal palynomorphs assem-blages constrained by environmental and climatic variables open new horizons for further non-pollen palynomorphs qualitative and quantitative research. (c) 2022 Elsevier Ltd. All rights reserved.Peer reviewe

Problems and methods of modern regional stratigraphy Abstracts

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