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The Arctic is one of the regions most sensitive to global warming, for which climate and environmental proxy archives are largely insufficient. Arctic driftwood provides a unique resource for research into the circumpolar entanglements of terrestrial, coastal and marine factors and processes – past, present, future. Here, first dendrochronological and wood anatomical insights into 639 Arctic driftwood samples are presented. Samples were collected across northern Norway (n =430) and north-western Iceland (n =209) in 2022. The overall potentials and limitations of Arctic driftwood to improve tree-ring chronologies from the boreal forest, and to reconstruct changes in sea ice extent and ocean current dynamics are discussed. Finally, the role driftwood has possibly played for Arctic settlements in the past hundreds of years is examined. [ABSTRACT FROM AUTHOR]

Mixed stands are currently supported as effective management options to reduce forest vulnerability to climate change. However, our issues about benefits of mixtures, mechanisms of their incidence and conditions for their effectiveness have yet been only partly clarified. We assessed the crown condition of Norway spruce (Picea abies /L./ Karst) and occurrence of symptoms caused by Armillaria spp. on spruce in a small area in the Drahanská vrchovina Highlands (Czech Republic) in differently mixed stands in 2002 and 2019. We found that although the broadleaf abundance affected the total defoliation of Norway spruce, the effect was unstable in time. The observed effect of altitudinal zones and Norway spruce abundance on the occurrence of symptoms of Armillaria root rot in spruce was also unstable. The drought during recent four years and the implemented forestry measures (salvage and intermediate felling) can be reasons for the relationship instability. We did not identify any statistically significant relationship between tree species diversity (Simpson's Index) and defoliation. [ABSTRACT FROM AUTHOR]

Knowledge about spatiotemporal variability of climate change effect on tree-ring width (TRW) and crown condition is essential to optimize the modelling of future forest ecosystem responses to the changing climate. Geographical differences in the climate–growth relationship are a reflection of the regional climatic conditions mainly. In this study, 175 Picea abies trees from the north-western edge of its geographical distribution in Central Norway were evaluated with respect to geographical and age-dependent differences during the common period of 1950–2015. The results showed that the most significant positive correlations between TRW and the current June temperature were unstable although the temperature increased. The correlations suddenly started to decrease (regardless of the site placement and tree age) at the beginning of the 1990s, but subsequently unexpectedly increased in the 2010s. The superposed epoch analysis revealed longer TRW regeneration of the southern plots (except over-mature trees) after negative pointer years compared to the northern plots. Previous summer temperature and related physiological processes (cone crops, storage of nutrients, etc.) significantly negatively affected P. abies growth in the current year. Additionally, our results showed that the selection of the chronology version (standard or residual) significantly affects the resulting correlations and thus must be carefully considered in dendroclimatological studies. Our main outputs can contribute to better understanding of the climate–growth relationship variability and general prediction of the radial growth. [ABSTRACT FROM AUTHOR]

Unraveling climatic effects on growth of oak - Europe's most ecologically and economically important forest species - has been the subject of many recent studies; however, more insight based on field data is necessary to better understand the relationship between climate and tree growth and to adapt forest management strategies to future climate change. In this report, we explore the influence of temperature, precipitation and drought variability on the productivity and vitality of oak stands in the Czech Highlands. We collected 180 cores from mature oaks (Quercus petraea) at four forest stands in the Czech Drahany Highlands. Standard dendromethods were used for sample preparation, ring width measurements, cross-dating, chronology development, and the assessment of growth-climate response patterns. Crown vitality was also evaluated, using the modified ICP Forests methodology. Late spring precipitation totals between May and June as well as the mean July temperature for the year of ring formation were found to be the most important factors for oak growth, whereas crown condition was significantly affected by spring and summer drought. This study is rep-resentative for similar bio-ecological habitats across Central Europe and can serve as a dendroclima-tological blueprint for earlier periods for which detailed meteorological information is missing [ABSTRACT FROM AUTHOR]

Climatic parameters are the main environmental factors affecting tree growth. The main aim of the presented study was to determine whether different oak species growing under contrasting environmental conditions show different sensitivity to climatic parameters. Four oak stands with Quercus robur, Quercus petraea, Quercus polycarpa and Quercus dalechampii growing in the same area were evaluated. Standard dendrochronological methods were used for sample preparation, ring width measurements, cross-dating, chronology development, and the assessment of growth-climate response patterns. Although the species grew under different environmental conditions, their local tree-ring chronologies are highly correlated. The radial growth responses to climatic parameters differ slightly, but the response depends more on local site conditions than on the oak species. At the same time, the strongest correlations between radial growth and climatic parameters were identical among species and sites. The amount of water available in the soil was the main climate-dependent factor limiting radial growth. Approximately since the 1990s, the distribution of rainfalls within the growing season has changed at the expense of spring precipitation. The significance of relative soil moisture content during spring for oak growth increased and the significance of summer values decreased. [ABSTRACT FROM AUTHOR]

Driftwood supply was a pivotal factor for the Norse expansion in medieval times and still exhibits an essential resource for Arctic settlements. The physical causes and societal consequences of long-term changes in the distribution of Arctic driftwood are, however, poorly understood. Here, we use dendrochronology to reconstruct the age and origin of 289 driftwood samples that were collected at remote shorelines in northeast Iceland. Based on 240 reference tree-ring width chronologies from the boreal forest zone, and an overall provenance success of 73%, we show that most of the driftwood is pine and larch from the Yenisei catchment in central Siberia. Our study reveals an abrupt decline in the amount of driftwood reaching Iceland since the 1980s, which is corroborated by the experience of local farmers and fishers. Despite the direct and indirect effects of changes in both, logging activity across Siberia as well as Arctic Ocean currents, the predicted amount of sea-ice loss under anthropogenic global warming is likely to terminate Iceland's driftwood supply by 2060 CE. • Driftwood was and is the most important resource for all Arctic settlements. • Most of the Icelandic driftwood originates from the Yenisei catchment in central Siberia. • An abrupt decline in the amount of Icelandic driftwood supply occurred in the 1980s. • Icelandic driftwood supply will cease under predicted sea-ice loss by 2060 CE. [ABSTRACT FROM AUTHOR]