| 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. |
- Guido, Maria Angela, et al.
(författare)
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Climate and vegetation dynamics of the Northern Apennines (Italy) during the Late Pleistocene and Holocene
- 2020
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791. ; 231, s. 1-17
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Tidskriftsartikel (refereegranskat)abstract
- This study reconstructs the regional vegetation and climate dynamics between the upper Late Pleistoceneand Holocene around Pian del Lago, a coastal mountain marshland located at 831 m asl in westernLiguria (NW-Italy), based on the pollen analysis of a 13 m-long sediment core. The record provided aunique opportunity to study a poorly documented period in northern Italy and across many parts ofsouthwestern Europe. We propose an event stratigraphy based upon the identification of seven interstadials(NAI-7 to NAI-1) spanning the upper Late Pleistocene. The correlation with other terrestrialrecords in Italy, and with Mediterranean marine sequences and the Greenland ice cores, permitted acoherent reconstruction of main environmental changes from >~43,000 cal. BP. Significantly, the pollenrecord indicates the persistence of a mesophilous mountain vegetation cover, mainly composed ofQuercus (deciduous and evergreen), Abies, Fagus and Alnus over the whole time period recorded. At theLast Glacial Maximum (LGM) and during the Late Würm Lateglacial, despite the presence of steppicvegetation composed of Artemisia, woodlands dominated by Pinus, with Abies, Picea, Fagus, Alnus andBetula are present. This forest composition provides an important insight into the history of Picea insouthern Europe and Late Pleistocene refugia for mesophilous species. During the Early Holocene, Pinusis first replaced by Abies and then by deciduous Quercus and mixed temperate species as the dominantforest component. Both arboreal and herbaceous anthropogenic pollen indicators only make theirappearance during the Late Holocene, attesting to the increasing importance of human activities.
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| 3. |
- Hannon, Gina E., et al.
(författare)
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Factors influencing late-Holocene vegetation dynamics and biodiversity on Hallands Väderö, SW Sweden : A statistical evaluation
- 2022
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Ingår i: Holocene. - : SAGE Publications. - 0959-6836. ; 32:11, s. 1317-1326
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Tidskriftsartikel (refereegranskat)abstract
- Forest composition characteristic of the Mid-Holocene has survived on Hallands Väderö, an island nature reserve off the south west coast of Sweden. Current veteran Tilia and Quercus trees contribute to a remarkably rich biodiversity of fungi, bryophytes, lichens and insects. Understanding which potential factors influence Holocene vegetation dynamics can support efforts to protect biodiversity, but the role of grazing and browsing has previously been difficult to evaluate because of the lack of long-term datasets. Palaeoecological analyses over the last c. 3000 years from a pond on the island reveal sustained presence of Quercus, Alnus, Tilia, Corylus and Ulmus, alongside increasing Fagus in recent centuries. Changes in grazing pressure have been documented since AD 1665 and a statistical approach was used to calculate the relative importance of grazing pressure, climate variability, and fire activity on the dynamics of selected taxa. Grazing was the main factor reducing population size of Fagus, Alnus, Tilia and Corylus on the island over the period AD 1665–1858, with warm winter temperatures and summer humidity having significant positive influences in the last millennium for Quercus, Alnus, Tilia and Corylus. The survival of large numbers of red-listed species is likely to be due to the continuity of large old trees, ancient forest composition and a distinctive disturbance history in a favourable climate.
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| 4. |
- Hannon, Gina E., et al.
(författare)
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Vegetation dynamics and Fire History in Färnebofjärden National Park, Central Sweden
- 2021
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Ingår i: The Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 31:1, s. 28-37
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Tidskriftsartikel (refereegranskat)abstract
- Palaeoecological studies can identify past trends in vegetation communities and processes over long time scales. Pollen, plant macrofossils and charcoalanalyses are used to reconstruct vegetation over the last 6400 years and provide information about former human impact and disturbance regimesin Färnebofjärden National Park, Central Sweden. Three specific conservation planning topics were addressed: (1) the changing ratio of conifers tobroadleaved trees; (2) the origin and history of the river meadows and the biodiverse Populus tremula meadows; (3) the role of fire in the maintenanceof biological values. Early diverse mixed broadleaved forest assemblages with pine were followed by significant declines of the more thermophilic forestelements prior to the expansion of spruce in the Iron Age. The rise to dominance of spruce was a ‘natural’ process that has been exaggerated byanthropogenic disturbance to artificially high levels today. The initial river meadow communities were facilitated by fire and frequent flooding events, butsubsequent dynamics have more definitely been supported by human activities. Rural abandonment during the last 100 years has led to woody successions.Fire has been a continual disturbance factor with an influence on conservation issues such as Picea abies dominance and the maintenance of diverse, nonforestcommunities. Present occurrence of fire is unusually low, but natural fire frequencies are increasing in the region.
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| 5. |
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| 6. |
- Molinari, Chiara, et al.
(författare)
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Fire Dynamics in Boreal Forests Over the 20th Century : A Data-Model Comparison
- 2021
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Ingår i: Frontiers in Ecology and Evolution. - : Frontiers Media SA. - 2296-701X. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Fire regimes across the world are expected to be altered by continuing variations in socio-economic conditions and climate. Current global fire-vegetation models are able to represent the present-day fire activity, but it is unclear how well they can simulate past or future scenarios. Here we use sedimentary charcoal-based biomass burning reconstructions to evaluate fire probability and total carbon flux emitted to the atmosphere per year simulated by the dynamic global vegetation model LPJ-GUESS with its incorporated fire model SIMFIRE-BLAZE across the boreal region during the last century. The analyses were run for the whole time period (1900–2000 CE), as well as for the intervals 1900–1950 CE and 1950–2000 CE. The data–model comparison for the 20th century reveals a general disagreement in trends between charcoal reconstructions (with decreasing or stable trends) and simulations (showing an overall increase) at both global (boreal forests) and continental scales (North America and Fennoscandia), as well as for most of the regional sub-areas (Canada, Norway and Sweden). The only exceptions are Alaska and Finland/Russia Karelia, where all the variables increase. Negative correlations between observations and model outputs are also recorded for the two different sub-periods, except for Alaska and North America during the time interval 1900–1950 CE, and Norway and Finland/Russia Karelia between 1950 and 2000 CE. Despite several uncertainties in charcoal records, main differences between modeled and observed fire activity are probably due to limitations in the representation of the human impact on fire regime (especially connected to forest management and landscape fragmentation) in the model simulations.
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| 7. |
- Molinari, Chiara, et al.
(författare)
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Fire-vegetation interactions during the last 11,000 years in boreal and cold temperate forests of Fennoscandia
- 2020
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791. ; 241
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Tidskriftsartikel (refereegranskat)abstract
- The long-term ecological interactions between fire and the composition of dominant trees and shrubs in boreal and cold temperate Fennoscandian forests are still under discussion. We hypothesized that fire-prone taxa should abound during periods and regions characterized by higher fire disturbance, while fire-intolerant taxa should dominate when and where fire activity is low. Biomass burning (BB) is here investigated based on 69 sedimentary charcoal records. For the same sites, the relative contribution of pollen-based reconstructions of dominant vegetation cover divided into three different fire-sensitivity classes is explored by means of a statistical approach. The overall patterns found across Fennoscandia suggest that Ericaceae (mainly Calluna), Pinus, Betula and Populus are strongly positively correlated with multi-millennial variability of BB in both boreal and cold temperate forests, confirming their fire-prone character (taxa adapted/favoured by burning). Positive but much weaker (and not always significant) relationships also exist between long-term trends in BB and Fagus, Quercus, Corylus, Alnus, Juniperus, Carpinus and Salix, fire-tolerant taxa that survive low/moderate intense fires because of specific functional traits or their rapid, enhanced regeneration after fire. A strong negative significant correlation is instead detected between BB and Picea, Ulmus Tilia, Fraxinus, which are fire-intolerant taxa and can locally disappear for a short time after a fire. This large-scale analysis supports our initial hypothesis that tree and shrub dominance was closely linked to biomass burning since the onset of the Holocene in the study regions. Fire was an important ecosystem disturbance in Fennoscandia influencing long-term vegetation dynamics and composition over the last 11,000 years, although human activities probably altered the strength of fire-vegetation interactions during more recent millennia.
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