Deglacial vegetation succession and Holocene tree-limit dynamics in the Scandes Mountains, west-central Sweden: stratigraphic data compared to megafossil evidence

Bergman, Jonas; Hammarlund, Dan; Hannon, Gina E.; Barnekow, Lena; Wohlfarth, Barbara

doi:10.1016/j.revpalbo.2004.12.005

Cited by 59 publications

(54 citation statements)

References 64 publications

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“…This inference agrees with several studies indicating a distinct shift to cooler and more snow rich conditions (Neoglaciation) around that time (e.g., Karlén, 1976;Caseldine and Matthews, 1987;Snowball and Sandgren, 1996;Bergman et al, 2005;Paus, 2010;Kullman, 2013).…”

Section: Aspects On Glacier and Climate Historysupporting

confidence: 92%

“…Subsequently and until the mid-Holocene, a diverse tree flora characterized glacier and snow cirques without perennial ice and currently situated several hundred meters above modern tree lines. These results parallel the situation in the southern Swedish Scandes (Öberg and Kullman, 2011a), suggesting a more generic pattern, with a richer tree flora and wider amplitude of Holocene tree-line and landscape change, than is usually assumed when focusing on more traditional palaeoarchives, such as peat bogs, soils, and lakes (e.g., Berglund et al, 1996; Karlén and Kuylenstierna, 1996; A B Barnekow, 1999;Seppä and Birks, 2001;Bergman et al, 2005;Mahaney and Kalm, 2012). Tree growth 600 -700 m above the modern tree lines in 9500 -8500 cal yr BP, as evidenced here for a particular type of habitat, is several hundred meters higher than estimated for the same time interval in previous studies that focused on low alpine terrain (e.g., Berglund et al, 1996;Karlén and Kuylenstierna, 1996;Barnekow, 1999;Seppä et al, 2004).…”

Section: High-elevation Tree Growth and Landscape Historysupporting

confidence: 62%

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New Aspects of High-Mountain Palaeobiogeography: A Synthesis of Data from Forefields of Receding Glaciers and Ice Patches in the Tärna and Kebnekaise Mountains, Swedish Lapland

Kullman¹,

Öberg²

2015

ARCTIC

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ABSTRACT. Recent recession of high-mountain glacier ice and perennial snow and ice patches has exposed megafossil and macrofossil tree remnants and peat, offering a new source of Holocene high alpine vegetation history in the Scandes. Radiocarbon dates of 90 tree megafossils from Swedish Lapland, 29 of which had not previously been published, range from 11 980 to 1950 cal yr BP. During the interval 9500 -8500 cal yr BP, mountain birch (Betula pubescens ssp. czerepanovii) and Scots pine (Pinus sylvestris) grew 600 -700 m higher upslope than they do today, which is a new and remarkable discovery. Subsequently, tree density gradually declined at higher elevations, and as the tree line moved downslope, the ratio of Betula to Pinus increased. Tree growth ceased around 4500 cal yr BP, presumably in response to the return of perennial ice and snow. A short episode of resumed tree growth of Betula indicates conditions warmer than present around 2000 years ago. Between c. 8500 and 7300 cal yr BP, Picea abies, Larix sibirica, Populus tremula, Sorbus aucuparia and Alnus incana were subordinate species on a forest floor dominated by plant species characteristic of prealpine or subalpine woodlands. Growth of trees as much as 700 m higher upslope than today around 9500 cal yr BP implies that summer temperatures at that time may have been 3.0˚C warmer than today's temperatures (corrected for land uplift). This inferred temperature difference between the early Holocene and the present concurs with changes in the Earth's orbital parameters.Key words: glaciers; tree growth; megafossils; macrofossils; Holocene; radiocarbon dating; climate change; Swedish Scandes RÉSUMÉ. Le recul récent de la glace de glacier, de la neige pérenne et des bancs de glace en haute montagne a permis de découvrir des mégafossiles et des macrofossiles de restes d'arbres et de tourbe, ce qui offre une nouvelle source d'histoire de la végétation alpine des Scandes en haute altitude pendant l'Holocène. La datation au carbone 14 de 90 mégafossiles d'arbres en provenance de la Laponie suédoise, dont 29 n'avaient jamais fait l'objet d'une publication, donne des résultats variant de 11 980 à 1 950 années cal. BP. Au cours de l'intervalle allant de 9 500 à 8 500 années cal. BP, le bouleau de montagne (Betula pubescens ssp. czerepanovii) et le pin sylvestre (Pinus sylvestris) poussaient à une hauteur de 600 à 700 m plus élevée qu'aujourd'hui, ce qui représente une découverte à la fois nouvelle et remarquable. Subséquemment, la densité des arbres a diminué graduellement en haute altitude, et au fur et à mesure que la limite forestière s'est mise à descendre, le rapport entre Betula et Pinus s'est accru. La croissance des arbres a cessé vers 4 500 années cal. BP, probablement en raison du retour de la glace et de la neige pérennes. Un bref épisode de reprise de la croissance des arbres de Betula indique la présence de conditions plus chaudes qu'à présent il y a environ 2 000 ans. Entre 8 500 et 7 300 années cal. BP environ, Picea abies, Larix sibirica, Populus tremu...

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Section: Aspects On Glacier and Climate Historysupporting

confidence: 92%

Section: High-elevation Tree Growth and Landscape Historysupporting

confidence: 62%

New Aspects of High-Mountain Palaeobiogeography: A Synthesis of Data from Forefields of Receding Glaciers and Ice Patches in the Tärna and Kebnekaise Mountains, Swedish Lapland

Kullman¹,

Öberg²

2015

ARCTIC

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“…Many other proxy records that are independent of vegetation patterns indicate a weaker signal for the 8200 cal yr BP event towards northern Fennoscandia. In western Scandinavia records based on loss-on-ignition analysis of lake sediments reveal a substantial climatic perturbation and clearly decreased aquatic productivity at about 8200 cal yr BP (Nesje et al, 2001;Bergman et al, 2005). However, in northern Fennoscandia the same methods do not display equally clear evidence for a cooling.…”

Section: Discussionmentioning

confidence: 96%

Spatial structure of the 8200 cal yr BP event in northern Europe

et al. 2007

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Abstract.A synthesis of well-dated high-resolution pollen records suggests a spatial structure in the 8200 cal yr BP event in northern Europe. The temperate, thermophilous tree taxa, especially Corylus, Ulmus, and Alnus, decline abruptly between 8300 and 8000 cal yr BP at most sites located south of 61 • N, whereas there is no clear change in pollen values at the sites located in the North-European tree-line region. Pollen-based quantitative temperature reconstructions and several other, independent palaeoclimate proxies, such as lacustrine oxygen-isotope records, reflect the same pattern, with no detectable cooling in the sub-arctic region. The observed patterns challenges the general view of the widespread occurrence of the 8200 cal yr BP event in the North Atlantic region. An alternative explanation is that the cooling during the 8200 cal yr BP event took place mostly during the winter and spring, and the ecosystems in the south responded sensitively to the cooling during the onset of the growing season. In contrast, in the sub-arctic area, where the vegetation was still dormant and lakes ice-covered, the cold event is not reflected in pollen-based or lake-sediment-based records.

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“…A gradual change to cooler and/or wetter conditions has been observed in Scandinavia at the end of the Holocene Thermal Maximum and the onset of the Neoglacial Period around 4000 cal yr BP, with a thicker snow cover in the Scandes Mountains that melted later in the year [11,14]. This climatic change caused a tree line descent in the Scandes Mountains [3,108,109] including the Storsjön catchment [11,88], as well as an increased formation of peatlands [110]. A lowering of the tree line has likely destabilized soils at high elevations in the Storsjön catchment and increased erosion during snowmelt floods, triggering the mechanisms of black layer formation described above.…”

Section: Relations To Climate and Vegetation Changesmentioning

confidence: 99%

“…9550 to 4000 cal yr BP (Subunit IIIa) is characterized by a steady decrease in the concentrations of lithogenic elements, which is probably mainly a dilution effect, as organic matter shows a parallel increase ( Figure 5). The input of terrestrial organic matter into the lake started to rise with the progressive development of soils and vegetation in the catchment, likely advancing to higher altitudes during this period [11,88]. Furthermore, warming temperatures led to increased organic productivity in the lake, as reflected by the probable introduction of magnetotactic bacteria (increase in κ ARM /SIRM and MDF ARM ; Figure 9) and to an increase in Si concentrations ( Figure 8) through elevated biogenic silica production, predominantly from diatoms, a sediment component identified in the SEM images ( Figure 10).…”

Section: Lake and Catchment Processes During The Holocene (Lithologicmentioning

confidence: 99%

Holocene Hydroclimate Variability in Central Scandinavia Inferred from Flood Layers in Contourite Drift Deposits in Lake Storsjön

et al. 2018

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Despite the societal importance of extreme hydroclimate events, few palaeoenvironmental studies of Scandinavian lake sediments have investigated flood occurrences. Here we present a flood history based on lithological, geochemical and mineral magnetic records of a Holocene sediment sequence collected from contourite drift deposits in Lake Storsjön (63.12 • N, 14.37 • E). After the last deglaciation, the lake began to form around 9800 cal yr BP, but glacial activity persisted in the catchment for~250 years. Element concentrations and mineral magnetic properties of the sediments indicate relatively stable sedimentation conditions during the Holocene. However, human impact in the form of expanding agriculture is evident from about 1100 cal yr BP, and intensified in the 20th century. Black layers containing iron sulphide appear irregularly throughout the sequence. The increased influx of organic matter during flood events led to decomposition and oxygen consumption, and eventually to anoxic conditions in the interstitial water preserving these layers. Elevated frequencies of black layer occurrence between 3600 and 1800 cal yr BP reflect vegetation changes in the catchment as well as large-scale climatic change. Soil erosion during snowmelt flood events increased with a tree line descent since the onset of the neoglacial period (~4000 cal yr BP). The peak in black layer occurrence coincides with a prominent solar minimum~2600 cal yr BP, which may have accentuated the observed pattern due to the prevalence of a negative NAO index, a longer snow accumulation period and consequently stronger snowmelt floods.

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Deglacial vegetation succession and Holocene tree-limit dynamics in the Scandes Mountains, west-central Sweden: stratigraphic data compared to megafossil evidence

Cited by 59 publications

References 64 publications

New Aspects of High-Mountain Palaeobiogeography: A Synthesis of Data from Forefields of Receding Glaciers and Ice Patches in the Tärna and Kebnekaise Mountains, Swedish Lapland

New Aspects of High-Mountain Palaeobiogeography: A Synthesis of Data from Forefields of Receding Glaciers and Ice Patches in the Tärna and Kebnekaise Mountains, Swedish Lapland

Spatial structure of the 8200 cal yr BP event in northern Europe

Holocene Hydroclimate Variability in Central Scandinavia Inferred from Flood Layers in Contourite Drift Deposits in Lake Storsjön

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