| 1. |
- Alenius, Teija, et al.
(författare)
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The environment they lived in: anthropogenic changes in local and regional vegetation composition in eastern Fennoscandia during the Neolithic
- 2020
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Ingår i: Vegetation History and Archaeobotany. - : Springer Science and Business Media LLC. - 0939-6314 .- 1617-6278. ; 30, s. 489-506
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Tidskriftsartikel (refereegranskat)abstract
- Understanding about regional versus local changes in vegetation is critical in answering archaeological questions, in particular at a time when humans are assumed to have caused higher disturbances at local scales rather than regional scales; this is the case during the Neolithic. The aim of this paper is to assess the impact of Neolithic land use on regional and local vegetation dynamics, plant composition and disturbance processes (e.g. fire) in eastern Fennoscandia. We apply the Landscape Reconstruction Algorithm (LRA) to high-resolution pollen records from three lacustrine sediment cores that cover the Neolithic period. We calculate changes in vegetation composition and the rate of plant compositional change. Fire dynamics are estimated as an indicator of land use, although fire can result from both natural and anthropogenic disturbances. Our results show that during the Early Neolithic, changes were mainly driven by natural and climate-induced factors and vegetation composition and fire activity were similar at both regional and local scales. From ca. 4000 bc onwards, trends in vegetation and fire dynamics start to differ between regional and local scales. This is due to local land uses that are overshadowed at the regional scale by climate-induced factors. The use of the LOVE model in pollen analyses is therefore very useful to highlight local land uses that are not visible by using REVEALS.
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| 2. |
- Giesecke, Thomas, et al.
(författare)
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The effect of past changes in inter-annual temperature variability on tree distribution limits
- 2010
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Ingår i: Journal of Biogeography. - : Wiley. - 1365-2699 .- 0305-0270. ; 37:7, s. 1394-1405
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Tidskriftsartikel (refereegranskat)abstract
- Aim The northern limits of temperate broadleaved species in Fennoscanndia are controlled by their requirements for summer warmth for successful regeneration and growth as well as by the detrimental effects of winter cold on plant tissue. However, occurrences of meteorological conditions with detrimental effects on individual species are rare events rather than a reflection of average conditions. We explore the effect of changes in inter-annual temperature variability on the abundances of the tree species Tilia cordata, Quercus robur and Ulmus glabra near their distribution limits using a process-based model of ecosystem dynamics. Location A site in central Sweden and a site in southern Finland were used as examples for the ecotone between boreal and temperate forests in Fennoscandia. The Finnish site was selected because of the availability of varve-thickness data. Methods The dynamic vegetation model LPJ-GUESS was run with four scenarios of inter-annual temperature forcing for the last 10,000 years. In one scenario the variability in the thickness of summer and winter varves from the annually laminated lake in Finland was used as a proxy for past inter-annual temperature variability. Two scenarios were devised to explore systematically the effect of stepwise changes in the variance and shape parameter of a probability distribution. All variability scenarios were run both with and without the long-term trend in Holocene temperature change predicted by an atmospheric general circulation model. Results Directional changes in inter-annual temperature variability have significant effects on simulated tree distribution limits through time. Variations in inter-annual temperature variability alone are shown to alter vegetation composition by magnitudes similar to the magnitude of changes driven by variation in mean temperatures. Main conclusions The varve data indicate that inter-annual climate variability has changed in the past. The model results show that past changes in species abundance can be explained by changes in the inter-annual variability of climate parameters as well as by mean climate. Because inter-annual climatic variability is predicted to change in the future, this component of climate change should be taken into account both when making projections of future plant distributions and when interpreting vegetation history.
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| 3. |
- Helmens, Karin F., et al.
(författare)
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Warm summers and rich biotic communities during N-Hemisphere deglaciation
- 2018
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Ingår i: Global and Planetary Change. - : Elsevier BV. - 0921-8181 .- 1872-6364. ; 167, s. 61-73
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Tidskriftsartikel (refereegranskat)abstract
- Detailed studies on fossil remains of plants or animals in glacial lake sediments are rare. As a result, environmental conditions right at the moment of deglaciation of the large N-Hemisphere ice-sheets remain largely unknown. Here we study three deglacial phases of the Fennoscandian Ice Sheet as a unique, repeated element in a long sediment record preserved at Soldl in northern Finland. We summarize extensive multi-proxy data (diatoms, phytoliths, chironomids, pollen, spores, non-pollen palynomorphs, macrofossils, lithology, loss-on-ignition, C/N) obtained on glacial lake sediments dated to the early Holocene (ca. 10 kyr BP), early MIS 3 (ca. 50 kyr BP) and early MIS 5a (ca. 80 kyr BP). In contrast to the common view of an unproductive ice-marginal environment, our study reconstructs rich ecosystems both in the glacial lake and along the shores with forest on recently deglaciated land. Higher than present-day summer temperatures are reconstructed based on a large variety of aquatic taxa. Rich biota developed due to the insolation-induced postglacial warming and high nutrient levels, the latter resulting from erosion of fresh bedrock and sediment, leaching of surface soils, decay of plant material under shallow water conditions, and sudden decreases in lake volume. Aquatic communities responded quickly to deglaciation and warm summers and reflect boreal conditions, in contrast to the terrestrial ecosystem which responded with some delay probably due to time required for slow soil formation processes. Birch forest is reconstructed upon deglaciation of the large LGM ice-sheet and shrub tundra following the probably faster melting smaller MIS 4 and MIS 5b ice-sheets. Our study shows that glacial lake sediments can provide valuable palaeo-environmental data, that aquatic biota and terrestrial vegetation rapidly accommodated to new environmental conditions during deglaciation, and that glacial lake ecosystems, and the carbon stored in their sediments, should be included in earth system modeling.
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| 4. |
- Johnson, Mark D., 1954, et al.
(författare)
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Unraveling Scandinavian geomorphology: the LiDAR revolution
- 2015
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Ingår i: GFF. - : Informa UK Limited. - 1103-5897 .- 2000-0863. ; 137:4, s. 245-251
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Tidskriftsartikel (refereegranskat)abstract
- In the observational sciences, technical advances are often followed by dramatic increases in scientific discoveries and improved theory. Leuwenhoek’s microscope and Galileo’s telescope gave us a “better look” at the microworld and the cosmos, which led to revolutions of past paradigms. In geomorphology and landscape analysis, similar advances have accompanied new maps and new mapping techniques. The first accurate globes, where the puzzle-piece fit of the southern continents was quickly noticed, were soon followed by the first mention of what would be continental drift. The first topographic maps were accompanied by similar shifts in thinking. For example, accurate topographic maps of the western US brought about the realization that even in arid regions, fluvial erosion can be the dominant landscaping force. Aerial photography provided a similar advance in observation, mapping and understanding. Satellite imagery of the Earth and other planets has dramatically revealed the geomorphic processes operating in inaccessible places, for example meteor impacts, volcanism and the importance of eolian and fluvial processes. Recent observations of Pluto and Mars attest to this fact. Satellite imagery also led to a revolution in glacial geomorphology by providing continent-wide images of features heretofore unnoticed, for example the palimpsest flow indicators of the Laurentide Ice Sheet (Boulton & Clark 1990). In the 90s, the production of digital elevation models (DEMs) and the development of geographic information system (GIS) tools allowed for new highly quantitative analysis of landscapes. The advent of LiDAR (Light Detection and Ranging) technology is poised to provide a similar rapid advance in observations and the potential for significant advances in geomorphic theory. We see that the ever increasing use of LiDAR technology is creating a similar leap forward in geomorphology, and this issuie celebrates that.
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| 5. |
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| 7. |
- Kreiser, Patrick, et al.
(författare)
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A Historical Investigation of the Strategic Process within Family Firms
- 2006
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Ingår i: Journal of Management History. - 1355-252X .- 1758-776X. ; 12:1, s. 100-114
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Tidskriftsartikel (refereegranskat)abstract
- Purpose of this paper: The primary purpose of this paper was to perform an in-depth analysis of the strategic process that occurs within family firms.Design/methodology/approach: This study analyzed the historical development of the growth strategies of five family firms in the United States, Finland, and Sweden.Findings: The results of this study suggest that family firms typically adopt conservative strategies in the early part of their life cycle. During their formative years, family firms often implement financially conservative strategies and place an emphasis on maintaining tight control of the strategic decision-making process within the family unit. However, the competitive pressures experienced by family firms over time often force these companies to embrace a more entrepreneurial posture during the latter stages of their life cycle.Research Implications: The stage in the company life cycle plays an important role in determining the strategic behavior of family firms. Future research aimed at replicating the results of this study may help shed further light on the strategic process that occurs within family firms.Practical Implications: Although the firms examined in this study were from various cultures, their strategic development over time was very similar. This tentatively suggests that the evolution of the strategic process that occurs within family firms may be generalizable across cultures.What is original/value of paper: Our findings indicate that there may be an important distinction between family firms and entrepreneurial organizations. That is, all family firms are not necessarily entrepreneurial, especially early on in their company life cycle.Paper Type: Research paperKey Words: Family Firms, Pulp and Paper Industry, Entrepreneurship, United States, Sweden, Finland
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| 8. |
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| 9. |
- Lappalainen, Hanna K., et al.
(författare)
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Pan-Eurasian Experiment (PEEX) : towards a holistic understanding of the feedbacks and interactions in the land-atmosphere-ocean-society continuum in the northern Eurasian region
- 2016
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 16:22, s. 14421-14461
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Tidskriftsartikel (refereegranskat)abstract
- The northern Eurasian regions and Arctic Ocean will very likely undergo substantial changes during the next decades. The Arctic-boreal natural environments play a crucial role in the global climate via albedo change, carbon sources and sinks as well as atmospheric aerosol production from biogenic volatile organic compounds. Furthermore, it is expected that global trade activities, demographic movement, and use of natural resources will be increasing in the Arctic regions. There is a need for a novel research approach, which not only identifies and tackles the relevant multi-disciplinary research questions, but also is able to make a holistic system analysis of the expected feedbacks. In this paper, we introduce the research agenda of the Pan-Eurasian Experiment (PEEX), a multi-scale, multi-disciplinary and international program started in 2012 (https://www.atm.helsinki.fi/peex/). PEEX sets a research approach by which large-scale research topics are investigated from a system perspective and which aims to fill the key gaps in our understanding of the feedbacks and interactions between the land-atmosphereaquatic-society continuum in the northern Eurasian region. We introduce here the state of the art for the key topics in the PEEX research agenda and present the future prospects of the research, which we see relevant in this context.
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| 10. |
- Löfgren, Kent, 1966-, et al.
(författare)
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Meeting the Challenges of Generational Change in the Teaching Profession : Towards a European Model for Intergenerational Teacher Collaboration
- 2013
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Ingår i: Educational Research eJournal. - : Educational Research e-Journal (EREJ). - 2254-0385. ; 2:2, s. 107-119
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Tidskriftsartikel (refereegranskat)abstract
- In a European-wide effort to improve the professional development of teachers, the 2AgePro project was conducted from November 2008 to October 2010. One of its goals was to develop and test different forms of intergenerational teacher collaboration among junior and senior teachers in primary and secondary schools. Another aim was to utilise the results from these pilots, which were conducted in the Czech Republic, Finland, Germany, the Netherlands, and Sweden, to create a model for intergenerational collaboration that could be used in any national or cultural setting. This article reports on the national pilots and proposes a European model for intergenerational collaboration for teachers.
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| 11. |
- Miettinen, Arttu, et al.
(författare)
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Non-destructive automatic determination of aspect ratio and cross-sectional properties of fibres
- 2015
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Ingår i: Composites. Part A, Applied science and manufacturing. - : Elsevier. - 1359-835X .- 1878-5840. ; 77, s. 188-194
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Tidskriftsartikel (refereegranskat)abstract
- We propose a novel method for computerized estimation of the length/diameter distribution of fibres in short-fibre reinforced composite. Having its basis in X-ray micro-computed tomography, the method is non-destructive and does not require user intervention. In addition to the aspect ratio, the method is also capable of estimating other geometrical properties of fibre cross-sections. Based on results on specially fabricated model material, the accuracy and precision of the method seems to be reasonable. An application to the manufacturing process of wood fibre reinforced thermoplastic composite is also shown, indicating a significant decrease in the aspect ratio of fibres during the processing steps.
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| 12. |
- Ojala, Antti E. K., et al.
(författare)
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Biases in radiocarbon dating of organic fractions in sediments from meromictic and seasonally hypoxic lakes
- 2019
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Ingår i: Bulletin of the Geological Society of Finland. - : GEOLOGICAL SOC FINLAND. - 0367-5211 .- 1799-4632. ; 91, s. 221-235
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Tidskriftsartikel (refereegranskat)abstract
- We present here radiocarbon dating results from two boreal lakes in Finland, which are permanently (meromictic) or seasonally stratified and contain continuous sequences of annually laminated sediments that started to form in the early Holocene. The radiocarbon dating results of different organic components were compared with the varve-based sediment chronologies. The deviation between the Lake Valkiajarvi varve chronology (8400 varve years 2-3% error estimate) and 33 C-14 dates taken from insoluble and soluble organic phases vary inconsistently throughout the Holocene. In extreme cases mean calibrated radiocarbon dates with 95.4% confidence levels (2 sigma) are -2350 and +2040 years offset when compared with the varve chronology. On average, the radiocarbon dates are offset by ca. +550 years. The deviation between the Lake Nautajarvi varve chronology (9898 varve years +/- 1% error estimate) and 26 C-14 dates analyzed with conventional and AMS methods indicates that radiocarbon dates are systematically older by 500-1300 years (about 900 years on average). This significant offset mean that radiocarbon dates obtained from organic bulk sediment of meromictic and seasonally hypoxic lakes must be cautiously interpreted because of the reservoir effect and carbon cycling at the sediment-water interface. Direct evidence was obtained from the dating of soluble fraction and insoluble organic matter from near bottom water in the monimolimnion of Lake Valkiajarvi, which yielded C-14 ages of 560 +/- 80 BP and 2070 +/- 140 BP, respectively. Our study reinforces previous results that age-depth models based on bulk sediment radiocarbon dates obtained on sediments of stratified lakes are of limited value for accurate dating of changes in land use and especially the commence of agriculture.
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| 13. |
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| 14. |
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| 15. |
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| 16. |
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| 17. |
- Rissanen, Antti J., et al.
(författare)
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Vertical stratification patterns of methanotrophs and their genetic controllers in water columns of oxygen-stratified boreal lakes
- 2021
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Ingår i: FEMS Microbiology Ecology. - : Oxford University Press. - 0168-6496 .- 1574-6941. ; 97:2
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Tidskriftsartikel (refereegranskat)abstract
- The vertical structuring of methanotrophic communities and its genetic controllers remain understudied in the water columns of oxygen-stratified lakes. Therefore, we used 16S rRNA gene sequencing to study the vertical stratification patterns of methanotrophs in two boreal lakes, Lake Kuivajarvi and Lake Lovojarvi. Furthermore, metagenomic analyses were performed to assess the genomic characteristics of methanotrophs in Lovojarvi and the previously studied Lake Alinen Mustajarvi. The methanotroph communities were vertically structured along the oxygen gradient. Alphaproteobacterial methanotrophs preferred oxic water layers, while Methylococcales methanotrophs, consisting of putative novel genera and species, thrived, especially at and below the oxic-anoxic interface and showed distinct depth variation patterns, which were not completely predictable by their taxonomic classification. Instead, genomic differences among Methylococcales methanotrophs explained their variable vertical depth patterns. Genes in clusters of orthologous groups (COG) categories L (replication, recombination and repair) and S (function unknown) were relatively high in metagenome-assembled genomes representing Methylococcales clearly thriving below the oxic-anoxic interface, suggesting genetic adaptations for increased stress tolerance enabling living in the hypoxic/anoxic conditions. By contrast, genes in COG category N (cell motility) were relatively high in metagenome-assembled genomes of Methylococcales thriving at the oxic-anoxic interface, which suggests genetic adaptations for increased motility at the vertically fluctuating oxic-anoxic interface.
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| 18. |
- Seppa, Heikki, et al.
(författare)
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Calibrated pollen accumulation rates as a basis for quantitative tree biomass reconstructions
- 2009
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Ingår i: The Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 19:2, s. 209-220
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Tidskriftsartikel (refereegranskat)abstract
- Recent investigations show that the pollen accumulation rate (PAR) of the common tree taxa is directly related to the biomass and, by inference, to the population size of the taxa around the study site. Fossil PAR records preserved in lakes provide therefore a potential proxy for quantitative biomass and population reconstructions. We use the high-resolution PAR records obtained from two accurately dated lake sediment cores in Finland to generate quantitative Holocene biomass records for Pinus, Picea and Betula, the most common tree taxa of the European Boreal forest. PAR values were calibrated to biomass values by comparing the modern PAR values with the modern biomass values and assuming a linear relationship between the past PAR and biomass values. The obtained PAR and biomass values and trends are remarkably coherent between the two records. Pinus has a stable Holocene biomass size and its modern biomass, about 20 t/ha corresponds with the natural Pinus biomass in the study regions. In contrast, Picea immigrated from the East during the mid Holocene, had a maximum biomass, 50-60 t/ha, at 3500-1000 cal. yr BP, and declined strongly during the last 1500-1000 years as a result of increased human activity and related rise of fire frequency. Thus, the modern Picea biomass in the study regions, about 22 t/ha, is only 35-40% of the natural Picea biomass. The results of this pilot study demonstrate the potential of the calibrated PAR data in quantitative biomass and population reconstructions. Such reconstructions can provide fresh insights into the structure of past plant communities and, when combined with records reflecting palaeoclimates, natural disturbances, and human activity, can help to disentangle the long-term importance of different enviromental drivers to changes in plants populations and ecosystems.
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| 19. |
- Snowball, Ian, et al.
(författare)
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FENNOSTACK and FENNORPIS: Varve dated Holocene palaeomagnetic secular variation and relative palaeointensity stacks for Fennoscandia
- 2007
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Ingår i: Earth and Planetary Science Letters. - : Elsevier BV. - 1385-013X .- 0012-821X. ; 255, s. 106-116
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Tidskriftsartikel (refereegranskat)abstract
- A Holocene palaeomagnetic secular variation master curve (FENNOSTACK) and a relative palaeointensity curve (FENNORPIS) for Fennoscandia are presented. These curves were produced by stacking palaeomagnetic data obtained from six annually laminated (varved) lake sediment sequences and one non-laminated sediment sequence. The six independent varve chronologies were combined to form a timescale, which extends between the present year and 10,200 Cal yr BP. Smoothed inclination and declination curves show trends that are similar to a palaeomagnetic secular variation curve for the United Kingdom, except that the ages of most of the statistically significant features are a few hundred years younger in the Fennoscandian data set. These differences are most likely due to excessively old ages of the United Kingdom features produced by the radiocarbon dating of bulk sediments. The standardized relative palaeointensity stack shows that the intensity of the geomagnetic field in Fennoscandia was highest at 2300 Cal yr BP and lowest at 7000 Cal yr BP. Three palaeointensity peaks (PIPs) and three palaeointensity lows (PILs) are identified in FENNORPIS and indicate that the intensity of geomagnetic field varied significantly on millennial scales in this region during the Holocene, but there is much scatter in the reconstruction prior to 8000 Cal yr BP. Higher frequency palaeointensity features present in individual records are not significant in the stacked data set, which implies that these are a result of local environmental bias. Significant discrepancies exist between the data and the output of the CALS7K.2 geomagnetic field model for the last 7000 yr. In particular, the largest declination swing observed in the data at 2670 Cal yr BP (feature “f”) is not produced by the model, which is most likely due to the influence of an inaccurately dated Icelandic secular variation curve on the model result. Short term trends in standardized relative palaeointensity do differ from the model output, but it is difficult to make a comparison because of the relative nature of the sediment record. Better absolute palaeointensity data are needed to reduce uncertainties in reconstructions of past geomagnetic field strength.
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| 20. |
- Yu, Changxun, et al.
(författare)
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Arsenic removal from contaminated brackish sea water by sorption onto Al hydroxides and Fe phases mobilized by land-use
- 2016
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 542, s. 923-934
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Tidskriftsartikel (refereegranskat)abstract
- This study examines the spatial and temporal distribution patterns of arsenic (As) in solid and aqueous materials along the mixing zone of an estuary, located in the south-eastern part of the Bothnian Bay and fed by a creek running through an acid sulfate (AS) soil landscape. The concentrations of As in solution form (<1 kDa) increase steadily from the creek mouth to the outer estuary, suggesting that inflowing seawater, rather than AS soil, is the major As source in the estuary. In sediments at the outer estuary, As was accumulated and diagenetically cycled in the surficial layers, as throughout much of the Bothnian Bay. In contrast, in sediments in the inner estuary, As concentrations and accumulation rates showed systematical peaks at greater depths. These peaks were overall consistent with the temporal trend of past As discharges from the Ronnskar smelter and the accompanied As concentrations in past sea-water of the Bothnian Bay, pointing to a connection between the historical smelter activities and the sediment-bound As in the inner estuary. However, the concentrations and accumulation rates of As peaked at depths where the smelter activities had already declined, but a large increase in the deposition of Al hydroxides and Fe phases occurred in response to intensified land-use in the mid 1960's and early 1970's. This correspondence suggests that, apart from the inflowing As-contaminated seawater, capture by Al hydroxides, Fe hydroxides and Fe-organic complexes is another important factor for As deposition in the inner estuary. After accumulating in the sediment, the solid-phase As was partly remobilized, as reflected by increased pore-water As concentrations, a process favored by As(V) reduction and high concentrations of dissolved organic matter. (C) 2015 Elsevier B.V. All rights reserved.
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| 21. |
- Åström, Mats E., 1963-, et al.
(författare)
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Sources, transport and sinks of beryllium in a coastal landscape affected by acidic soils
- 2018
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Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier. - 0016-7037 .- 1872-9533. ; 232, s. 288-302
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Tidskriftsartikel (refereegranskat)abstract
- Beryllium (Be) sources, transport and sinks were studied in a coastal landscape where acidic soils (acid sulfate soils) have developed after drainage of fine-grained sulfide-bearing sediments. The study included the determination of total abundance and speciation of Be in a variety of solid and aqueous materials in both the terrestrial and estuarine parts of the landscape. A major feature was that despite normal (background) Be concentration in the sulfide-bearing sediments, the Be leaching from these sediments after O2-exposure and acid sulfate soil development were extensive, with concentrations up to 76 μg L−1 in soil water, 39 μg L−1 in runoff and 12 μg L−1 in low-order streams. These high Be concentrations were mainly in the solution form (i.e., passing a 1 kilodalton filter) and modelled to be dominated by free Be2+. The extensive Be release within, and leaching from the acid sulfate soils was controlled by pH, with a critical value of 4.0 below which the Be concentrations increased strongly. Although plagioclase and mica were most likely the main carriers of Be within these soils, it is suggested that other minerals such as Be hydroxides, Al hydroxides carrying Be, and Be sulfides are the main contributors of the abundance of dissolved Be in the acidic waters. When the acidic and Be-rich creek water was neutralized in the estuary of relatively low salinity, the dominating solution form of Be was removed by transformation to particles, reflected in the suspended particulate matter that had hydroxylamine hydrochloride extractable Be up to 17 mg kg−1 and ammonium acetate EDTA extractable Be up to 4 mg kg−1. In corresponding pristine materials (parent material of the acid sulfate soils) in the catchment, the median Be extractability with these reagents were only 0.3 and 0.05 mg kg−1, respectively. As the Be-rich suspended particulate matter ultimately became benthic sediment, the Be was preserved in terms of total concentrations but underwent to some extent changes in speciation, including release from hydroxides and concomitant scavenging by organic matter and particle surfaces.
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