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Papers by Olafur Eggertsson

Research paper thumbnail of Northern European Database of Long term Forest Experiments (NoLTFoX)

Research paper thumbnail of Aboveground growth responses of mature Picea sitchensis forest stand at different levels of soil warming

Climate warming is occurring faster in high latitudes and that trend is predicted to continue. Ho... more Climate warming is occurring faster in high latitudes and that trend is predicted to continue. How vegetation responds to past warming or to manipulation experiments has proven to be quite site-specific. To better understand the underlying reasons for contrasting responses it is important to study both the direct and the indirect responses to warming that are often mediated through the underlying soil processes.The ForHot site in Iceland offers possibilities to look at the indirect warming effects that are mediated through soil processes. There, a natural soil warming experiment was created in May 2008 by a major earthquake that shifted geothermal bedrock channels to previously cold areas. In this study we use an experimental site with 50-year-old Sitka spruce (Picea sitchensis) and soil warming gradient ranging from 0 to +6 °C between 2008 to 2018. The main objective is to get deeper insights into how rising soil temperatures will affect aboveground growth dynamics in sub-Arctic fo...

Research paper thumbnail of Origin of the driftwood on the coasts of Iceland; a dendrochronological study

Jökull

In many places along the extensive coastline of Iceland driftwood has been washed ashore over a l... more In many places along the extensive coastline of Iceland driftwood has been washed ashore over a long period of time. Although the amount of driftwood varies from place to place it isfound on almost every beach along the coast. The wood originates in the boreal forest regions of Russia/Siberia. Rivers which drain these forested areas carry driftwood into the Arctic Ocean, where it is caught in drifting ice and transported by the oceanic currents.

Research paper thumbnail of Braided motivations for Iceland’s first wave of mass emigration to North America after the 1875 Askja eruption

Regional environmental change, Mar 19, 2024

More than 14,000 Icelanders emigrated to North America between 1870 and 1914 CE. Mass movement fr... more More than 14,000 Icelanders emigrated to North America between 1870 and 1914 CE. Mass movement from Iceland accelerated the year after the explosive eruption of Askja in 1875, and both contemporary and recent commentators have linked the two circumstances. Despite an abundant scholarship on Icelandic emigration in this period, the direct and indirect roles of the eruption as a possible stimulus remain unclear. Here, we engage critically with a range of contemporary source materials as well as meteorological and climatological information to reassess where Askja fits into the picture of Iceland's first wave of mass migration. We find that emigration was undoubtedly fuelled by the hardships of Icelanders and their growing contacts with countrymen already in the Americas, and that the highest proportions of emigrants came from counties most directly impacted by the Askja eruption. However, it also emerges that the eruption served as a lever for interested parties in Britain and Canada to persuade large numbers of desirable migrants to settle in North America. Our study highlights the opportunities that discrete episodes of volcanic activity present to probe the complex interrelationships of nature and society.

Research paper thumbnail of Defoliation and dieback of Sitka spruce in Reykjavík, Iceland

Icelandic Agricultural Sciences, 2021

The green spruce aphid Elatobium abietinum is an important defoliating pest of Sitka spruce (Pice... more The green spruce aphid Elatobium abietinum is an important defoliating pest of Sitka spruce (Picea sitchensis) in Iceland. A comparison of two urban Sitka stands in Reykjavík, from 2013-2017, reveals a distinct defoliation difference between trees located near a main road (94% defoliated) and several hundred meters away from heavy traffic (47%). Chemical analyses of the spruce needles demonstrate substantially higher nitrogen ratios in trees near traffic. Furthermore, the recently warming winter temperatures promoted larger overwintering aphid populations since 2003, as well as a shift of mass outbreaks from autumn to spring, accompanied by distinct growth suppressions one year after an aphid population spike in the post-2003 tree-ring data. The results of this study indicate that the mechanisms triggering Sitka spruce dieback in Reykjavík include a combination of increasing winter temperatures, more frequent and severe green spruce aphid outbreaks, as well as elevated N values in t...

Research paper thumbnail of Growth form and leaf habit drive contrasting effects of Arctic amplification in long‐lived woody species

Global Change Biology, Aug 1, 2023

Research paper thumbnail of Origin of the Arctic driftwood - a dendrological study

Research paper thumbnail of Defoliation and dieback of Sitka spruce in Reykjavík, Iceland

Icelandic Agricultural Sciences, 2021

The green spruce aphid Elatobium abietinum is an important defoliating pest of Sitka spruce (Pice... more The green spruce aphid Elatobium abietinum is an important defoliating pest of Sitka spruce (Picea sitchensis) in Iceland. A comparison of two urban Sitka stands in Reykjavík, from 2013-2017, reveals a distinct defoliation difference between trees located near a main road (94% defoliated) and several hundred meters away from heavy traffic (47%). Chemical analyses of the spruce needles demonstrate substantially higher nitrogen ratios in trees near traffic. Furthermore, the recently warming winter temperatures promoted larger overwintering aphid populations since 2003, as well as a shift of mass outbreaks from autumn to spring, accompanied by distinct growth suppressions one year after an aphid population spike in the post-2003 tree-ring data. The results of this study indicate that the mechanisms triggering Sitka spruce dieback in Reykjavík include a combination of increasing winter temperatures, more frequent and severe green spruce aphid outbreaks, as well as elevated N values in the needles of urban trees.

Research paper thumbnail of Potential and limitation of combining terrestrial and marine growth records from Iceland

Global and Planetary Change, Aug 1, 2017

Research paper thumbnail of Using Arctic driftwood at the interface of marine and terrestrial (paleo-)environmental research

Past Global Changes Magazine, Aug 1, 2016

Research paper thumbnail of The importance of Arctic driftwood for interdisciplinary global change research (Short Communication / Methodological note)

Czech polar reports, Feb 19, 2023

The work was supported by the Bilateral cooperation in driftwood research (EHP-BFNU-OVNKM-3-050-2... more The work was supported by the Bilateral cooperation in driftwood research (EHP-BFNU-OVNKM-3-050-2020) and the SustES project-Adaptation strategies for sustainable ecosystem services and food security under adverse environmental conditions (CZ.

Research paper thumbnail of The long-term effects of climatic factors on radial growth of downy birch (Betula pubescens) and rowan (Sorbus aucuparia) in East Iceland

Icelandic Agricultural Sciences, 2020

The aim of this study was to investigate the tree-ring growth of rowan (Sorbus aucuparia L.) and ... more The aim of this study was to investigate the tree-ring growth of rowan (Sorbus aucuparia L.) and downy birch (Betula pubescens Ehrh.) in Ranaskógur, a forest in East Iceland, and to determine its response to climate factors during the past century. Tree-core samples were collected in September 2018 and from those a tree-ring width (TRW) chronology and a standardized tree-ring index (TRI) chronology were produced. A statistical analysis between the chronologies and monthly mean temperatures and total monthly precipitation was carried out. The study found that both species had similar radial growth during the past century. The growth of birch responded significantly positively to June and July temperatures, while rowan responded significantly positively to July and August temperatures. The growth of neither species was significantly affected by precipitation across the whole period. However, in the 1940s to early 1960s, rowan growth correlated significantly with June precipitation, and birch with April and May precipitation.

Research paper thumbnail of Origin of the Arctic driftwood - a dendrochronological study

Research paper thumbnail of Origin of the driftwood on the coasts areas of Iceland, a dendrochronological study

Research paper thumbnail of Radial growth-based assessment of sites effects on pedunculate and greyish oak in southern Romania

Science of The Total Environment, 2019

The dendroclimatology of Quercus robur and Q. pedunculiflora was studied. • Different growth patt... more The dendroclimatology of Quercus robur and Q. pedunculiflora was studied. • Different growth patterns among sites and within species were observed. • There is a relationship between offset earlywood and climatic drivers between varieties. • Winter and spring represent key seasons in separating tardive from praecox varieties.

Research paper thumbnail of Agriculture in the Arctic

Research paper thumbnail of Tree rings and past climate in the Arctic

Research paper thumbnail of Climate change and fire in the Arctic

Research paper thumbnail of Use and evaluation of the ACIA forest and agriculture scenarios Use and evaluation of the ACIA forest and agriculture scenarios

Encyclopedia of Earth > Encyclopedia of Eart... > Articles &amp... more Encyclopedia of Earth > Encyclopedia of Eart... > Articles > Use and evaluation o... ... This is Section 14.4 of the Arctic Climate Impact Assessment. ... Lead Author: Glenn P. Juday; Contributing Authors: Valerie Barber, Paul Duffy, Hans Linderholm, Scott Rupp, Steve Sparrow, ...

Research paper thumbnail of Agriculture in the Arctic Agriculture in the Arctic

... Duffy, Hans Linderholm, Scott Rupp, Steve Sparrow, Eugene Vaganov, John Yarie; Consulting Aut... more ... Duffy, Hans Linderholm, Scott Rupp, Steve Sparrow, Eugene Vaganov, John Yarie; Consulting Authors: Edward Berg, Rosanne D'Arrigo, Olafur Eggertsson,VV Furyaev, Edward H. Hogg, Satu Huttunen, Gordon Jacoby,V.Ya. ... Gitay, H., S. Brown,W. Easterling and B. Jallow, 2001 ...

Research paper thumbnail of Northern European Database of Long term Forest Experiments (NoLTFoX)

Research paper thumbnail of Aboveground growth responses of mature Picea sitchensis forest stand at different levels of soil warming

Climate warming is occurring faster in high latitudes and that trend is predicted to continue. Ho... more Climate warming is occurring faster in high latitudes and that trend is predicted to continue. How vegetation responds to past warming or to manipulation experiments has proven to be quite site-specific. To better understand the underlying reasons for contrasting responses it is important to study both the direct and the indirect responses to warming that are often mediated through the underlying soil processes.The ForHot site in Iceland offers possibilities to look at the indirect warming effects that are mediated through soil processes. There, a natural soil warming experiment was created in May 2008 by a major earthquake that shifted geothermal bedrock channels to previously cold areas. In this study we use an experimental site with 50-year-old Sitka spruce (Picea sitchensis) and soil warming gradient ranging from 0 to +6 °C between 2008 to 2018. The main objective is to get deeper insights into how rising soil temperatures will affect aboveground growth dynamics in sub-Arctic fo...

Research paper thumbnail of Origin of the driftwood on the coasts of Iceland; a dendrochronological study

Jökull

In many places along the extensive coastline of Iceland driftwood has been washed ashore over a l... more In many places along the extensive coastline of Iceland driftwood has been washed ashore over a long period of time. Although the amount of driftwood varies from place to place it isfound on almost every beach along the coast. The wood originates in the boreal forest regions of Russia/Siberia. Rivers which drain these forested areas carry driftwood into the Arctic Ocean, where it is caught in drifting ice and transported by the oceanic currents.

Research paper thumbnail of Braided motivations for Iceland’s first wave of mass emigration to North America after the 1875 Askja eruption

Regional environmental change, Mar 19, 2024

More than 14,000 Icelanders emigrated to North America between 1870 and 1914 CE. Mass movement fr... more More than 14,000 Icelanders emigrated to North America between 1870 and 1914 CE. Mass movement from Iceland accelerated the year after the explosive eruption of Askja in 1875, and both contemporary and recent commentators have linked the two circumstances. Despite an abundant scholarship on Icelandic emigration in this period, the direct and indirect roles of the eruption as a possible stimulus remain unclear. Here, we engage critically with a range of contemporary source materials as well as meteorological and climatological information to reassess where Askja fits into the picture of Iceland's first wave of mass migration. We find that emigration was undoubtedly fuelled by the hardships of Icelanders and their growing contacts with countrymen already in the Americas, and that the highest proportions of emigrants came from counties most directly impacted by the Askja eruption. However, it also emerges that the eruption served as a lever for interested parties in Britain and Canada to persuade large numbers of desirable migrants to settle in North America. Our study highlights the opportunities that discrete episodes of volcanic activity present to probe the complex interrelationships of nature and society.

Research paper thumbnail of Defoliation and dieback of Sitka spruce in Reykjavík, Iceland

Icelandic Agricultural Sciences, 2021

The green spruce aphid Elatobium abietinum is an important defoliating pest of Sitka spruce (Pice... more The green spruce aphid Elatobium abietinum is an important defoliating pest of Sitka spruce (Picea sitchensis) in Iceland. A comparison of two urban Sitka stands in Reykjavík, from 2013-2017, reveals a distinct defoliation difference between trees located near a main road (94% defoliated) and several hundred meters away from heavy traffic (47%). Chemical analyses of the spruce needles demonstrate substantially higher nitrogen ratios in trees near traffic. Furthermore, the recently warming winter temperatures promoted larger overwintering aphid populations since 2003, as well as a shift of mass outbreaks from autumn to spring, accompanied by distinct growth suppressions one year after an aphid population spike in the post-2003 tree-ring data. The results of this study indicate that the mechanisms triggering Sitka spruce dieback in Reykjavík include a combination of increasing winter temperatures, more frequent and severe green spruce aphid outbreaks, as well as elevated N values in t...

Research paper thumbnail of Growth form and leaf habit drive contrasting effects of Arctic amplification in long‐lived woody species

Global Change Biology, Aug 1, 2023

Research paper thumbnail of Origin of the Arctic driftwood - a dendrological study

Research paper thumbnail of Defoliation and dieback of Sitka spruce in Reykjavík, Iceland

Icelandic Agricultural Sciences, 2021

The green spruce aphid Elatobium abietinum is an important defoliating pest of Sitka spruce (Pice... more The green spruce aphid Elatobium abietinum is an important defoliating pest of Sitka spruce (Picea sitchensis) in Iceland. A comparison of two urban Sitka stands in Reykjavík, from 2013-2017, reveals a distinct defoliation difference between trees located near a main road (94% defoliated) and several hundred meters away from heavy traffic (47%). Chemical analyses of the spruce needles demonstrate substantially higher nitrogen ratios in trees near traffic. Furthermore, the recently warming winter temperatures promoted larger overwintering aphid populations since 2003, as well as a shift of mass outbreaks from autumn to spring, accompanied by distinct growth suppressions one year after an aphid population spike in the post-2003 tree-ring data. The results of this study indicate that the mechanisms triggering Sitka spruce dieback in Reykjavík include a combination of increasing winter temperatures, more frequent and severe green spruce aphid outbreaks, as well as elevated N values in the needles of urban trees.

Research paper thumbnail of Potential and limitation of combining terrestrial and marine growth records from Iceland

Global and Planetary Change, Aug 1, 2017

Research paper thumbnail of Using Arctic driftwood at the interface of marine and terrestrial (paleo-)environmental research

Past Global Changes Magazine, Aug 1, 2016

Research paper thumbnail of The importance of Arctic driftwood for interdisciplinary global change research (Short Communication / Methodological note)

Czech polar reports, Feb 19, 2023

The work was supported by the Bilateral cooperation in driftwood research (EHP-BFNU-OVNKM-3-050-2... more The work was supported by the Bilateral cooperation in driftwood research (EHP-BFNU-OVNKM-3-050-2020) and the SustES project-Adaptation strategies for sustainable ecosystem services and food security under adverse environmental conditions (CZ.

Research paper thumbnail of The long-term effects of climatic factors on radial growth of downy birch (Betula pubescens) and rowan (Sorbus aucuparia) in East Iceland

Icelandic Agricultural Sciences, 2020

The aim of this study was to investigate the tree-ring growth of rowan (Sorbus aucuparia L.) and ... more The aim of this study was to investigate the tree-ring growth of rowan (Sorbus aucuparia L.) and downy birch (Betula pubescens Ehrh.) in Ranaskógur, a forest in East Iceland, and to determine its response to climate factors during the past century. Tree-core samples were collected in September 2018 and from those a tree-ring width (TRW) chronology and a standardized tree-ring index (TRI) chronology were produced. A statistical analysis between the chronologies and monthly mean temperatures and total monthly precipitation was carried out. The study found that both species had similar radial growth during the past century. The growth of birch responded significantly positively to June and July temperatures, while rowan responded significantly positively to July and August temperatures. The growth of neither species was significantly affected by precipitation across the whole period. However, in the 1940s to early 1960s, rowan growth correlated significantly with June precipitation, and birch with April and May precipitation.

Research paper thumbnail of Origin of the Arctic driftwood - a dendrochronological study

Research paper thumbnail of Origin of the driftwood on the coasts areas of Iceland, a dendrochronological study

Research paper thumbnail of Radial growth-based assessment of sites effects on pedunculate and greyish oak in southern Romania

Science of The Total Environment, 2019

The dendroclimatology of Quercus robur and Q. pedunculiflora was studied. • Different growth patt... more The dendroclimatology of Quercus robur and Q. pedunculiflora was studied. • Different growth patterns among sites and within species were observed. • There is a relationship between offset earlywood and climatic drivers between varieties. • Winter and spring represent key seasons in separating tardive from praecox varieties.

Research paper thumbnail of Agriculture in the Arctic

Research paper thumbnail of Tree rings and past climate in the Arctic

Research paper thumbnail of Climate change and fire in the Arctic

Research paper thumbnail of Use and evaluation of the ACIA forest and agriculture scenarios Use and evaluation of the ACIA forest and agriculture scenarios

Encyclopedia of Earth > Encyclopedia of Eart... > Articles &amp... more Encyclopedia of Earth > Encyclopedia of Eart... > Articles > Use and evaluation o... ... This is Section 14.4 of the Arctic Climate Impact Assessment. ... Lead Author: Glenn P. Juday; Contributing Authors: Valerie Barber, Paul Duffy, Hans Linderholm, Scott Rupp, Steve Sparrow, ...

Research paper thumbnail of Agriculture in the Arctic Agriculture in the Arctic

... Duffy, Hans Linderholm, Scott Rupp, Steve Sparrow, Eugene Vaganov, John Yarie; Consulting Aut... more ... Duffy, Hans Linderholm, Scott Rupp, Steve Sparrow, Eugene Vaganov, John Yarie; Consulting Authors: Edward Berg, Rosanne D'Arrigo, Olafur Eggertsson,VV Furyaev, Edward H. Hogg, Satu Huttunen, Gordon Jacoby,V.Ya. ... Gitay, H., S. Brown,W. Easterling and B. Jallow, 2001 ...