We assessed the utility of using the sediment total organic carbon/total nitrogen (C/N) ratio as ... more We assessed the utility of using the sediment total organic carbon/total nitrogen (C/N) ratio as an indicator of paleoclimate changes in the eastern Baltic area during the late glacial and early Holocene. The C/N ratio in sediments from Lake Lielais Svētiņ u, eastern Latvia, was compared with other sediment variables that are used as proxies of past climate and environment. Analysis revealed that although the organic matter (OM) content in late glacial sediments was extremely low, the C/N ratio captured information about OM origin, and fluctuations in the ratio tracked climate oscillations. The C/N ratio was significantly positively correlated with pollen-inferred mean summer temperature. Therefore, C/N ratio was lower under colder conditions, indicating a predominantly phytoplankton origin of OM, and was higher during warmer conditions, when there was more vegetation around the lake. A strong positive correlation between C/N ratio and the paleopigment beta carotene suggested that elevated phytoplankton production resulted from higher nutrient availability that was controlled largely by the input of terrestrial OM to the lake during warmer climate episodes. Thus, C/N ratio was a good indicator of paleoclimate changes, at least for the late glacial period, when generally cold conditions prevailed. This study also demonstrates the power of multi-proxy paleolimnological analyses for investigating past environmental changes in lakes and their watersheds.
We used HPLC to identify and quantify pigments in a Holocene sediment record from large, shallow ... more We used HPLC to identify and quantify pigments in a Holocene sediment record from large, shallow Lake Peipsi, Estonia. The aim of our study was to track the influence of long-term climate change (i.e. temperature fluctuations) on past dynamics of aquatic primary producers. Sedimentary pigments were separated and quantified in 182 samples that span the last ca. 10,000 years. There was an increasing trend in sedimentary pigment concentrations from basal to upper sediment layers, suggesting a gradual increase in lake trophic status through time. Using additive models, our results suggested that primary producer dynamics in Lake Peipsi were closely related to temperature fluctuations. We, however, identified two periods (early Holocene and after ca. 2.5 cal ka BP) when the relationship between primary producer composition and temperature was weak, suggesting the influence of additional drivers on the primary producer community. We postulate that: (a) the increase of primary producer biomass in the early Holocene could have been caused by input of allochthonous organic matter and nutrients from the flooded areas when water level in Lake Peipsi was increasing, and (b) changes in the abundance and structure of primary producer assemblages since ca. 2.5 cal ka BP was related to widespread agricultural activities in the Lake Peipsi catchment. These results suggest that human activities can disrupt the relationship between the primary producer community and temperature in large, shallow lakes.
Understanding the long-term dynamics of ecological communities on the centuries-to-millennia scal... more Understanding the long-term dynamics of ecological communities on the centuries-to-millennia scale is important for explaining present-day biodiversity patterns. Placing these patterns in a historical context could yield reliable tools for predicting possible future scenarios. Paleoarchives of macro+ and micro-fossil remains, and most importantly biomarkers such as fossil pigments and ancient DNA present in various sedimentary deposits, allow long term changes in ecological communities to be analysed. We use recent compilations of data including fossil pigments, metabarcoding of sedimentary ancient DNA and microfossils together with data analysis to understand the impact of gradual versus abrupt climate changes on a lake`s ecosystem status over the last 14.5 kyr. We give examples of hypotheses that need long-term data, which can be addressed using well-established paleoproxy variables. These variables describe the climate, together with vegetation change and the appearance of anthro...
Concentration of spherical particles in oil shale fly ash and their deposition onto areas surroun... more Concentration of spherical particles in oil shale fly ash and their deposition onto areas surrounding Narva power plants and far (background) sites in Southeastern Estonia was studied. It was found that due to their relatively low background values, spherical particles are more sensitive indicators of oil shale combustion emissions than chemical components, especially calcium, of oil-shale ash. As the concentration of spherical particles in fly ash was determined to be highly variable depending on combustion technologies and regimes, their use for quantitative tracing is complicated in practice. The same variability, however, leaves us a chance to refine the backward-tracing methods for fly ash, distinguishing different types of combustion devices by their source signatures. It was found that wintertime (snow-based) field campaigns are preferred to the warm season (based on rainwater sampling) ones owing to their relatively lower background concentrations, but both campaigns are nee...
1Department of Geosciences and Geography, University of Helsinki, Helsinki, Finland 2Institute of... more 1Department of Geosciences and Geography, University of Helsinki, Helsinki, Finland 2Institute of Geology, Tallinn University of Technology, Tallinn, Estonia 3Institute of Soil and Plant Sciences, Faculty of Agriculture, Latvia University of Agriculture, Jelgava, Latvia 4Lake and Peatland Research Centre, Alojas District, Puikule, Latvia 5Department of Biogeography and Palaeoecology, Adam Mickiewicz University, Poznań, Poland 6Faculty of Geography and Earth Sciences, University of Latvia, Riga, Latvia 7Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark 8Laboratory of Wetlands Ecology and Monitoring, Adam Mickiewicz University, Poznań, Poland 9Senckenberg Research Institute & Natural History Museum, BIK-F, TSP6 Evolution and Climate, Frankfurt, Germany 10Climate Dynamics and Landscape Evolution, GFZ German Research Centre for Geosciences, Potsdam, Germany 11Institute of Earth Sciences, Heidelberg University, Heidelberg, Germany __...
This study of the Kanna calcareous spring fen on Saaremaa, the largest island of Estonia, elucida... more This study of the Kanna calcareous spring fen on Saaremaa, the largest island of Estonia, elucidates its history of fen development and vegetation diversity over the last 9,200 years. Pollen, spores, non-pollen palynomorphs, macrofossils, loss-on-ignition and humification index analyses were carried out to reconstruct fen succession, vegetation development, environmental changes and human impact. Hierarchical clustering, ordination analysis and linear regression were applied to examine the vegetation composition and richness patterns through time and to identify the potential environmental drivers underlying these patterns. Our results suggest reverse mire development from bog to fen, a rare occurrence and contrary to typical mire autogenic succession from groundwater fed to rainwater fed. Kanna developed as a small bog for the first 2,000 years from 9,200 to 7,200 cal yrs bp . Changes to the hydrological regime around 7,200 cal yrs bp , due to a warmer and drier climate and land uplift, caused a change from an ombrotrophic to a minerotrophic environment. Typical spring fen characteristics developed ca. 5,000 cal yrs bp and continued until ca. 400 cal yrs bp , when the fen was fed by calcareous mineral-rich groundwater and reached very high floristic diversity with various calciphilous and relict plant taxa. We conclude that general changes in the Kanna fen succession, vegetation community and diversity are associated with climatic changes. The present high diversity of the fen is a result of a long-term stable fen environment, which may have been even higher in the past. However, the pollen richness has decreased during the last 400 years, possibly due to human or natural factors.
ContextAnthropogenic and environmental changes are reshaping landscapes across the globe. In this... more ContextAnthropogenic and environmental changes are reshaping landscapes across the globe. In this context, understanding the patterns, drivers, and consequences of these changes is one of the central challenges of humankind.PurposeWe aim to test the possibilities of combining modern multidisciplinary approaches to reconstruct the land-cover and linking the changes in land-cover to socioeconomic shifts in southern Estonia over the last 200 years.MethodsThe historical records from five, and maps from six time periods and 79 pollen-based land-cover reconstructions from four lakes are used to determine the land-cover structure and composition and are thereafter combined with the literature based analyses of socioeconomic changes.ResultsAll information sources recorded similar changes in the land-cover. The anthropogenic deforestation was comparable to today’s (approximately 50%) during the nineteenth century. Major political and socioeconomic changes led to the intensification of agriculture and maximal deforestation (60–85%) at the beginning of the twentieth century. The land nationalisation following the Soviet occupation led to the reforestation of the less productive agricultural lands. This trend continued until the implementation of European Union agrarian subsidies at the beginning of the twenty first century.ConclusionsPollen-based reconstructions provide a trustworthy alternative to historical records and maps. Accounting for source specific biases is essential when dealing with any data source. The landscape’s response to socioeconomic changes was considerable in Estonia over the last 200 years. Changes in land ownership and the global agricultural market are major drivers in determining the strength and direction of the land-cover change.
We report the first geochemically confirmed findings of the Askja volcano (Iceland) 30 AD 1875 er... more We report the first geochemically confirmed findings of the Askja volcano (Iceland) 30 AD 1875 eruption cryptotephra in Eastern Europe. The cryptotephra finding in Latvia 31 is the easternmost finding of the Askja AD 1875 so far, providing an important time 32 marker in the sediments. Even though low concentrations of Askja AD 1875 rhyolitic 33 POST-PRINT 2 glass shards were recorded, our findings suggest the possibilities of also tracing other historical cryptotephras in lacustrine and peat sediments in Eastern Europe. We use the 35 Askja AD 1875 tephra isochrone to synchronize pollen data of human activities, i.e. the 36 rye (Secale cereale) cultivation. Our comparison of Secale pollen from two sites reveals 37 that there were minor dissimilarities in the timing of highest rye cultivation, and that synchronous decrease of rye cultivation occurred at both sites few years after the Askja eruption at AD 1875.
Lake sediments have the ability to record palaeoinformation that affords to identify trails of va... more Lake sediments have the ability to record palaeoinformation that affords to identify trails of various bygone climate events. The aim of this study was to find out if sedimentary organic carbon and nitrate nitrogen dissolved in pore water (pOC and pNO3-N, respectively) and phosphorus (P) can be used for climate reconstruction. A 3.5-m sediment core of a large (3,555 km2) shallow (mean depth 7 m) Lake Peipsi (Northern Europe) was examined. Radiocarbon dating of the core revealed that in time it covers the last 10,000 yrs. Sediment P was categorised into different pools using a 4-step extraction procedure [1]. The concentrations of pNO3-N and pOC were determined directly from absorption spectra of pore water. The high-resolution scale (22–53 yrs) changes in the age-related distribution of pOC, pNO3-N and different P fractions were compared with well-known climate events that have occurred in the region over the Holocene [2–5]. The ability of pOC, pNO3-N and P fractions to reflect clim...
We assessed the utility of using the sediment total organic carbon/total nitrogen (C/N) ratio as ... more We assessed the utility of using the sediment total organic carbon/total nitrogen (C/N) ratio as an indicator of paleoclimate changes in the eastern Baltic area during the late glacial and early Holocene. The C/N ratio in sediments from Lake Lielais Svētiņ u, eastern Latvia, was compared with other sediment variables that are used as proxies of past climate and environment. Analysis revealed that although the organic matter (OM) content in late glacial sediments was extremely low, the C/N ratio captured information about OM origin, and fluctuations in the ratio tracked climate oscillations. The C/N ratio was significantly positively correlated with pollen-inferred mean summer temperature. Therefore, C/N ratio was lower under colder conditions, indicating a predominantly phytoplankton origin of OM, and was higher during warmer conditions, when there was more vegetation around the lake. A strong positive correlation between C/N ratio and the paleopigment beta carotene suggested that elevated phytoplankton production resulted from higher nutrient availability that was controlled largely by the input of terrestrial OM to the lake during warmer climate episodes. Thus, C/N ratio was a good indicator of paleoclimate changes, at least for the late glacial period, when generally cold conditions prevailed. This study also demonstrates the power of multi-proxy paleolimnological analyses for investigating past environmental changes in lakes and their watersheds.
We used HPLC to identify and quantify pigments in a Holocene sediment record from large, shallow ... more We used HPLC to identify and quantify pigments in a Holocene sediment record from large, shallow Lake Peipsi, Estonia. The aim of our study was to track the influence of long-term climate change (i.e. temperature fluctuations) on past dynamics of aquatic primary producers. Sedimentary pigments were separated and quantified in 182 samples that span the last ca. 10,000 years. There was an increasing trend in sedimentary pigment concentrations from basal to upper sediment layers, suggesting a gradual increase in lake trophic status through time. Using additive models, our results suggested that primary producer dynamics in Lake Peipsi were closely related to temperature fluctuations. We, however, identified two periods (early Holocene and after ca. 2.5 cal ka BP) when the relationship between primary producer composition and temperature was weak, suggesting the influence of additional drivers on the primary producer community. We postulate that: (a) the increase of primary producer biomass in the early Holocene could have been caused by input of allochthonous organic matter and nutrients from the flooded areas when water level in Lake Peipsi was increasing, and (b) changes in the abundance and structure of primary producer assemblages since ca. 2.5 cal ka BP was related to widespread agricultural activities in the Lake Peipsi catchment. These results suggest that human activities can disrupt the relationship between the primary producer community and temperature in large, shallow lakes.
Understanding the long-term dynamics of ecological communities on the centuries-to-millennia scal... more Understanding the long-term dynamics of ecological communities on the centuries-to-millennia scale is important for explaining present-day biodiversity patterns. Placing these patterns in a historical context could yield reliable tools for predicting possible future scenarios. Paleoarchives of macro+ and micro-fossil remains, and most importantly biomarkers such as fossil pigments and ancient DNA present in various sedimentary deposits, allow long term changes in ecological communities to be analysed. We use recent compilations of data including fossil pigments, metabarcoding of sedimentary ancient DNA and microfossils together with data analysis to understand the impact of gradual versus abrupt climate changes on a lake`s ecosystem status over the last 14.5 kyr. We give examples of hypotheses that need long-term data, which can be addressed using well-established paleoproxy variables. These variables describe the climate, together with vegetation change and the appearance of anthro...
Concentration of spherical particles in oil shale fly ash and their deposition onto areas surroun... more Concentration of spherical particles in oil shale fly ash and their deposition onto areas surrounding Narva power plants and far (background) sites in Southeastern Estonia was studied. It was found that due to their relatively low background values, spherical particles are more sensitive indicators of oil shale combustion emissions than chemical components, especially calcium, of oil-shale ash. As the concentration of spherical particles in fly ash was determined to be highly variable depending on combustion technologies and regimes, their use for quantitative tracing is complicated in practice. The same variability, however, leaves us a chance to refine the backward-tracing methods for fly ash, distinguishing different types of combustion devices by their source signatures. It was found that wintertime (snow-based) field campaigns are preferred to the warm season (based on rainwater sampling) ones owing to their relatively lower background concentrations, but both campaigns are nee...
1Department of Geosciences and Geography, University of Helsinki, Helsinki, Finland 2Institute of... more 1Department of Geosciences and Geography, University of Helsinki, Helsinki, Finland 2Institute of Geology, Tallinn University of Technology, Tallinn, Estonia 3Institute of Soil and Plant Sciences, Faculty of Agriculture, Latvia University of Agriculture, Jelgava, Latvia 4Lake and Peatland Research Centre, Alojas District, Puikule, Latvia 5Department of Biogeography and Palaeoecology, Adam Mickiewicz University, Poznań, Poland 6Faculty of Geography and Earth Sciences, University of Latvia, Riga, Latvia 7Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark 8Laboratory of Wetlands Ecology and Monitoring, Adam Mickiewicz University, Poznań, Poland 9Senckenberg Research Institute & Natural History Museum, BIK-F, TSP6 Evolution and Climate, Frankfurt, Germany 10Climate Dynamics and Landscape Evolution, GFZ German Research Centre for Geosciences, Potsdam, Germany 11Institute of Earth Sciences, Heidelberg University, Heidelberg, Germany __...
This study of the Kanna calcareous spring fen on Saaremaa, the largest island of Estonia, elucida... more This study of the Kanna calcareous spring fen on Saaremaa, the largest island of Estonia, elucidates its history of fen development and vegetation diversity over the last 9,200 years. Pollen, spores, non-pollen palynomorphs, macrofossils, loss-on-ignition and humification index analyses were carried out to reconstruct fen succession, vegetation development, environmental changes and human impact. Hierarchical clustering, ordination analysis and linear regression were applied to examine the vegetation composition and richness patterns through time and to identify the potential environmental drivers underlying these patterns. Our results suggest reverse mire development from bog to fen, a rare occurrence and contrary to typical mire autogenic succession from groundwater fed to rainwater fed. Kanna developed as a small bog for the first 2,000 years from 9,200 to 7,200 cal yrs bp . Changes to the hydrological regime around 7,200 cal yrs bp , due to a warmer and drier climate and land uplift, caused a change from an ombrotrophic to a minerotrophic environment. Typical spring fen characteristics developed ca. 5,000 cal yrs bp and continued until ca. 400 cal yrs bp , when the fen was fed by calcareous mineral-rich groundwater and reached very high floristic diversity with various calciphilous and relict plant taxa. We conclude that general changes in the Kanna fen succession, vegetation community and diversity are associated with climatic changes. The present high diversity of the fen is a result of a long-term stable fen environment, which may have been even higher in the past. However, the pollen richness has decreased during the last 400 years, possibly due to human or natural factors.
ContextAnthropogenic and environmental changes are reshaping landscapes across the globe. In this... more ContextAnthropogenic and environmental changes are reshaping landscapes across the globe. In this context, understanding the patterns, drivers, and consequences of these changes is one of the central challenges of humankind.PurposeWe aim to test the possibilities of combining modern multidisciplinary approaches to reconstruct the land-cover and linking the changes in land-cover to socioeconomic shifts in southern Estonia over the last 200 years.MethodsThe historical records from five, and maps from six time periods and 79 pollen-based land-cover reconstructions from four lakes are used to determine the land-cover structure and composition and are thereafter combined with the literature based analyses of socioeconomic changes.ResultsAll information sources recorded similar changes in the land-cover. The anthropogenic deforestation was comparable to today’s (approximately 50%) during the nineteenth century. Major political and socioeconomic changes led to the intensification of agriculture and maximal deforestation (60–85%) at the beginning of the twentieth century. The land nationalisation following the Soviet occupation led to the reforestation of the less productive agricultural lands. This trend continued until the implementation of European Union agrarian subsidies at the beginning of the twenty first century.ConclusionsPollen-based reconstructions provide a trustworthy alternative to historical records and maps. Accounting for source specific biases is essential when dealing with any data source. The landscape’s response to socioeconomic changes was considerable in Estonia over the last 200 years. Changes in land ownership and the global agricultural market are major drivers in determining the strength and direction of the land-cover change.
We report the first geochemically confirmed findings of the Askja volcano (Iceland) 30 AD 1875 er... more We report the first geochemically confirmed findings of the Askja volcano (Iceland) 30 AD 1875 eruption cryptotephra in Eastern Europe. The cryptotephra finding in Latvia 31 is the easternmost finding of the Askja AD 1875 so far, providing an important time 32 marker in the sediments. Even though low concentrations of Askja AD 1875 rhyolitic 33 POST-PRINT 2 glass shards were recorded, our findings suggest the possibilities of also tracing other historical cryptotephras in lacustrine and peat sediments in Eastern Europe. We use the 35 Askja AD 1875 tephra isochrone to synchronize pollen data of human activities, i.e. the 36 rye (Secale cereale) cultivation. Our comparison of Secale pollen from two sites reveals 37 that there were minor dissimilarities in the timing of highest rye cultivation, and that synchronous decrease of rye cultivation occurred at both sites few years after the Askja eruption at AD 1875.
Lake sediments have the ability to record palaeoinformation that affords to identify trails of va... more Lake sediments have the ability to record palaeoinformation that affords to identify trails of various bygone climate events. The aim of this study was to find out if sedimentary organic carbon and nitrate nitrogen dissolved in pore water (pOC and pNO3-N, respectively) and phosphorus (P) can be used for climate reconstruction. A 3.5-m sediment core of a large (3,555 km2) shallow (mean depth 7 m) Lake Peipsi (Northern Europe) was examined. Radiocarbon dating of the core revealed that in time it covers the last 10,000 yrs. Sediment P was categorised into different pools using a 4-step extraction procedure [1]. The concentrations of pNO3-N and pOC were determined directly from absorption spectra of pore water. The high-resolution scale (22–53 yrs) changes in the age-related distribution of pOC, pNO3-N and different P fractions were compared with well-known climate events that have occurred in the region over the Holocene [2–5]. The ability of pOC, pNO3-N and P fractions to reflect clim...
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