Jesper Björklund, Kristina Seftigen, Ryszard J. Kaczka, Miloš Rydval, Rob Wilson,
The published literature of the past 20 years expresses inconsistent terminology for the Blue Intensity (BI) method that could lead to confusion in analysis and interpretation. In this technical note we propose a standard terminology based around the prevalent use of BI for the variant that is positively correlated with wood density derived from X-ray and equivalent wood anatomical techniques. We highlight significant practical advantages of this standard terminology for data analysis, scientific ...
Tópico(s): Plant Water Relations and Carbon Dynamics
2024 - Elsevier BV | Dendrochronologia
Kerstin Treydte, Laibao Liu, Ryan S. Padrón, Elisabet Martínez‐Sancho, Flurin Babst, David Frank, Arthur Geßler, Ansgar Kahmen, Benjamin Poulter, Sonia I. Seneviratne, Annemiek I. Stegehuis, Rob Wilson, Laia Andreu‐Hayles, Roderick J. Bale, Z. Bednarz, Tatjana Boettger, Frank Berninger, Ulf Büntgen, Valérie Daux, Isabel Dorado‐Liñán, Jan Esper, Michael Friedrich, Mary Gagen, Michael Grabner, Håkan Grudd, Björn Gunnarsson, Emília Gutiérrez, Polona Hafner, Marika Haupt, Emmi Hilasvuori, Ingo Heinrich, Gerhard Helle, Risto Jalkanen, H. Jungner, Maarit Kalela‐Brundin, A. Keßler, Andreas Kirchhefer, Stephan Klesse, Marek Krąpiec, Tom Levanič, Markus Leuenberger, Hans W. Linderholm, Danny McCarroll, Valérie Masson‐Delmotte, Sławomira Pawełczyk, Anna Pazdur, Octavi Planells, Rūtilė Pukienė, Katja T. Rinne‐Garmston, Iain Robertson, Antonio Saracino, Matthias Saurer, Gerhard H. Schleser, Kristina Seftigen, Rolf Siegwolf, Eloni Sonninen, M. Stiévenard, Elżbieta Szychowska‐Kra̧piec, Malgorzata Szymaszek, Luigi Todaro, J. Waterhouse, Martin Weigl-Kuska, Rosemarie B. Weigt, Rupert Wimmer, Ewan J. Woodley, Adomas Vitas, Giles Young, Neil J. Loader,
Tópico(s): Climate variability and models
2023 - Nature Portfolio | Nature Geoscience
Jesper Björklund, Kristina Seftigen, Markus Stoffel, Marina V. Fonti, Sven Kottlow, David Frank, Jan Esper, Patrick Fonti, Hugues Goosse, Håkan Grudd, Björn E. Gunnarson, Daniel Nievergelt, Elena Pellizzari, Marco Carrer, Georg von Arx,
Tópico(s): Geology and Paleoclimatology Research
2023 - Nature Portfolio | Nature
Julie Edwards, Kevin J. Anchukaitis, Björn E. Gunnarson, Charlotte Pearson, Kristina Seftigen, Georg von Arx, Hans W. Linderholm,
Abstract Basaltic fissure eruptions, which are characteristic of Icelandic volcanism, are extremely hazardous due to the large quantities of gases and aerosols they release into the atmosphere. The 1783–1784 CE Laki eruption was one of the most significant high‐latitude eruptions in the last millennium and had substantial environmental and climatic impacts. Contemporary observations recorded the presence of a sulfuric haze over Iceland and Europe, which caused famine from vegetation damage and resulted ...
Tópico(s): Geology and Paleoclimatology Research
2022 - Wiley | Paleoceanography and Paleoclimatology
Roland Barthel, Moa Stangefelt, Markus Giese, Michelle Nygren, Kristina Seftigen, Deliang Chen,
Recently, groundwater in Sweden has attracted media attention due to supply shortages caused by dry periods and low groundwater levels. About half of Swedish drinking water stems from groundwater. The small Swedish aquifers are highly dependent on frequent and sufficient recharge. Groundwater recharge forms the link between meteorological and groundwater drought and thus the main link between climate change and sustainable water supply. This study evaluated whether the current knowledge on groundwater ...
Tópico(s): Hydrology and Watershed Management Studies
2021 - Taylor & Francis | Geografiska Annaler Series A Physical Geography
Ulf Büntgen, Kathy Allen, Kevin J. Anchukaitis, Dominique Arseneault, Étienne Boucher, Achim Bräuning, Snigdhansu Chatterjee, Paolo Cherubini, Olga V. Churakova, Christophe Corona, Fabio Gennaretti, Jussi Grießinger, Sébastien Guillet, Joël Guiot, Björn E. Gunnarson, Samuli Helama, Philipp Hochreuther, Malcolm K. Hughes, Peter Huybers, Alexander V. Kirdyanov, Paul J. Krusic, Josef Ludescher, Wolfgang Jens-Henrik Meier, Vladimir S. Myglan, Kurt Nicolussi, Clive Oppenheimer, Frederick Reinig, Matthew W. Salzer, Kristina Seftigen, A. Stine, Markus Stoffel, Scott St. George, Ernesto Tejedor, A. M. Trevino, Valérie Trouet, Jianglin Wang, Rob Wilson, Bao Yang, Guobao Xu, Jan Esper,
Abstract Tree-ring chronologies underpin the majority of annually-resolved reconstructions of Common Era climate. However, they are derived using different datasets and techniques, the ramifications of which have hitherto been little explored. Here, we report the results of a double-blind experiment that yielded 15 Northern Hemisphere summer temperature reconstructions from a common network of regional tree-ring width datasets. Taken together as an ensemble, the Common Era reconstruction mean correlates ...
Tópico(s): Climate variability and models
2021 - Nature Portfolio | Nature Communications
Deliang Chen, Peng Zhang, Kristina Seftigen, Tinghai Ou, Markus Giese, Roland Barthel,
Climate change poses additional risks for natural and human systems including the hydrological cycle, leading to altered temporal and spatial variation of hydroclimatic conditions. This work assessed the current understanding of the dryness and wetness conditions in Sweden over the last two millenniums based on proxy and instrumental data, as well as climate model simulations and projections until the end of the twenty-first century. The assessment represents a summary of the existing literature ...
Tópico(s): Plant Water Relations and Carbon Dynamics
2020 - Taylor & Francis | Geografiska Annaler Series A Physical Geography
Jesper Björklund, Kristina Seftigen, Patrick Fonti, Daniel Nievergelt, Georg von Arx,
The most frequently and successfully used tree-ring parameters for the study of temperature variations are ring width and maximum latewood density (MXD). MXD is preferred over ring width due to a more prominent association with temperature. In this study we explore the dendroclimate potential of dendroanatomy based on the first truly well replicated dataset. Twenty-nine mature living Pinus sylvestris trees were sampled in North-eastern Finland at the cool and moist boreal forest zone, close to the ...
Tópico(s): Forest ecology and management
2020 - Elsevier BV | Dendrochronologia
Fredrik Charpentier Ljungqvist, Alma Piermattei, Andrea Seim, Paul J. Krusic, Ulf Büntgen, Minhui He, Alexander V. Kirdyanov, Jürg Luterbacher, Lea Schneider, Kristina Seftigen, David W. Stahle, Ricardo Villalba, Bao Yang, Jan Esper,
To place recent hydroclimate changes, including drought occurrences, in a long-term historical context, tree-ring records serve as an important natural archive. Here, we evaluate 46 millennium-long tree-ring based hydroclimate reconstructions for their Data Homogeneity, Sample Replication, Growth Coherence, Chronology Development, and Climate Signal based on criteria published by Esper et al. (2016) to assess tree-ring based temperature reconstructions. The compilation of 46 individually calibrated ...
Tópico(s): Climate variability and models
2020 - Elsevier BV | Quaternary Science Reviews
Kristina Seftigen, Mauricio Fuentes, Fredrik Charpentier Ljungqvist, Jesper Björklund,
High-resolution hydroclimate proxy records are essential for distinguishing natural hydroclimate variability from possible anthropogenically-forced changes, since instrumental precipitation observations are too short to represent the whole spectrum of natural variability. In Northern Europe, progress in this field has been hampered by a relative lack of long and truly moisture-sensitive proxy records. In this study, we provide the first assessment of the dendroclimatic potential of Blue Intensity ( ...
Tópico(s): Forest ecology and management
2020 - Springer Science+Business Media | Climate Dynamics
Jesper Björklund, Miloš Rydval, Jonathan S. Schurman, Kristina Seftigen, Volodymyr Trotsiuk, Pavel Janda, Martin Mikoláš, Martin Dušátko, Vojtěch Čada, Radek Bače, Miroslav Svoboda,
A tree's radial growth sequence can be thought of as an aggregate of different growth components such as age and size limitations, presence or absence of disturbance events, continuous impact of climate variability and variance induced by unknown origin. The potentially very complex growth patterns with prominent temporal and spatial variability imply that our understanding of climate-vegetation feedbacks essentially benefits from the expansion of large tree ring networks into data-poor regions, ...
Tópico(s): Forest ecology and management
2019 - Elsevier BV | Agricultural and Forest Meteorology
Fredrik Charpentier Ljungqvist, Peter Thejll, Jesper Björklund, Björn E. Gunnarson, Alma Piermattei, Miloš Rydval, Kristina Seftigen, Bård Støve, Ulf Büntgen,
We test the application of parametric, non-parametric, and semi-parametric calibration models for reconstructing summer (June–August) temperature from a set of tree-ring width and density data on the same dendro samples from 40 sites across Europe. By comparing the performance of the three calibration models on pairs" of tree-ring width (TRW) and maximum density (MXD) or maximum blue intensity (MXBI), we test whether a non-linear temperature response is more prevalent in TRW or MXD (MXBI) data, and whether ...
Tópico(s): Forest ecology and management
2019 - Elsevier BV | Dendrochronologia
Fredrik Charpentier Ljungqvist, Andrea Seim, Paul J. Krusic, J. Fidel González‐Rouco, J. Werner, Edward R. Cook, Eduardo Zorita, Jürg Luterbacher, Elena Xoplaki, Georgia Destouni, Elena García‐Bustamante, Camilo Melo‐Aguilar, Kristina Seftigen, Jianglin Wang, Mary Gagen, Jan Esper, Olga N Solomina, Dominik Fleitmann, Ulf Büntgen,
Abstract The long-term relationship between temperature and hydroclimate has remained uncertain due to the short length of instrumental measurements and inconsistent results from climate model simulations. This lack of understanding is particularly critical with regard to projected drought and flood risks. Here we assess warm-season co-variability patterns between temperature and hydroclimate over Europe back to 850 CE using instrumental measurements, tree-ring based reconstructions, and climate ...
Tópico(s): Climate variability and models
2019 - IOP Publishing | Environmental Research Letters
Hans W. Linderholm, Marie Nicolle, Pierre Francus, Konrad Gajewski, Samuli Helama, Atte Korhola, Olga N Solomina, Zicheng Yu, Peng Zhang, W. J. D'Andrea, Maxime Debret, Dmitry Divine, Björn E. Gunnarson, Neil J. Loader, Nicolas Masséi, Kristina Seftigen, Elizabeth K. Thomas, J. Werner, Sofia Andersson, Annika Berntsson, Tomi P. Luoto, Liisa Nevalainen, Saija Saarni, Minna Väliranta,
Abstract. Reanalysis data show an increasing trend in Arctic precipitation over the 20th century, but changes are not homogenous across seasons or space. The observed hydroclimate changes are expected to continue and possibly accelerate in the coming century, not only affecting pan-Arctic natural ecosystems and human activities, but also lower latitudes through the atmospheric and ocean circulations. However, a lack of spatiotemporal observational data makes reliable quantification of Arctic hydroclimate ...
Tópico(s): Climate change and permafrost
2018 - Copernicus Publications | Climate of the past
Kristina Seftigen, David Frank, Jesper Björklund, Flurin Babst, Benjamin Poulter,
Abstract Aim Radial growth and foliage dynamics of trees both play a significant role in the terrestrial carbon cycle. Yet, crucial knowledge gaps exist in how these two growth components are linked. Our goal is to help bridge these gaps by providing a Northern Hemispheric survey of the connections between, and drivers of, inter‐annual wood and canopy–landscape dynamics and phenology. Location Northern (>30° N) forest ecosystems. Methods We compared a multispecies network of ca . 700 annually resolved ...
Tópico(s): Ecology and Vegetation Dynamics Studies
2018 - Wiley | Global Ecology and Biogeography
Flurin Babst, Paul Bodesheim, Noah Charney, A. D. Friend, Martin P. Girardin, Stefan Klesse, D. J. Moore, Kristina Seftigen, Jesper Björklund, Olivier Bouriaud, Andria Dawson, R. Justin DeRose, Michael C. Dietze, Annemarie Eckes‐Shephard, Brian J. Enquist, David Frank, Miguel D. Mahecha, Benjamin Poulter, Sydne Record, Valérie Trouet, Rachael H. Turton, Zhen Zhang, Margaret E. K. Evans,
The demand for large-scale and long-term information on tree growth is increasing rapidly as environmental change research strives to quantify and forecast the impacts of continued warming on forest ecosystems. This demand, combined with the now quasi-global availability of tree-ring observations, has inspired researchers to compile large tree-ring networks to address continental or even global-scale research questions. However, these emergent spatial objectives contrast with paleo-oriented research ...
Tópico(s): Ecology and Vegetation Dynamics Studies
2018 - Elsevier BV | Quaternary Science Reviews
Jesper Björklund, Kristina Seftigen, Fritz Hans Schweingruber, Patrick Fonti, Georg von Arx, Marina V. Bryukhanova, Henri E. Cuny, Marco Carrer, Daniele Castagneri, David Frank,
Interannual variability of wood density - an important plant functional trait and environmental proxy - in conifers is poorly understood. We therefore explored the anatomical basis of density. We hypothesized that earlywood density is determined by tracheid size and latewood density by wall dimensions, reflecting their different functional tasks. To determine general patterns of variability, density parameters from 27 species and 349 sites across the Northern Hemisphere were correlated to tree-ring ...
Tópico(s): Forest ecology and management
2017 - Wiley | New Phytologist
Mauricio Fuentes, Riikka Salo, Jesper Björklund, Kristina Seftigen, Peng Zhang, Björn E. Gunnarson, Juan Carlos Aravena, Hans W. Linderholm,
To assess past climate variability in west-central Scandinavia, a new 972-year-long temperature reconstruction, based on adjusted delta blue intensity (ΔBI adj ), was created. Presently, it is the longest blue intensity chronology in Fennoscandia and the third longest in the northern hemisphere. Measurements were obtained from 119 tree line Scots pine ( Pinus sylvestris L.) samples from Rogen, in the central Scandinavian Mountains, Sweden. Early and latewood blue intensity absorption data were used to ...
Tópico(s): Geology and Paleoclimatology Research
2017 - SAGE Publishing | The Holocene
Kristina Seftigen, Hugues Goosse, François Klein, Deliang Chen,
Abstract. The integration of climate proxy information with general circulation model (GCM) results offers considerable potential for deriving greater understanding of the mechanisms underlying climate variability, as well as unique opportunities for out-of-sample evaluations of model performance. In this study, we combine insights from a new tree-ring hydroclimate reconstruction from Scandinavia with projections from a suite of forced transient simulations of the last millennium and historical intervals ...
Tópico(s): Plant Water Relations and Carbon Dynamics
2017 - Copernicus Publications | Climate of the past
Raúl Sánchez‐Salguero, J. Julio Camarero, Emília Gutiérrez, J. Fidel González‐Rouco, Antonio Gazol, Gabriel Sangüesa‐Barreda, Laia Andreu‐Hayles, Juan Carlos Linares, Kristina Seftigen,
Growth models can be used to assess forest vulnerability to climate warming. If global warming amplifies water deficit in drought-prone areas, tree populations located at the driest and southernmost distribution limits (rear-edges) should be particularly threatened. Here, we address these statements by analyzing and projecting growth responses to climate of three major tree species (silver fir, Abies alba; Scots pine, Pinus sylvestris; and mountain pine, Pinus uncinata) in mountainous areas of NE ...
Tópico(s): Forest ecology and management
2016 - Wiley | Global Change Biology
Edward R. Cook, Richard Seager, Yochanan Kushnir, Keith R. Briffa, Ulf Büntgen, David Frank, Paul J. Krusic, Willy Tegel, Gerard van der Schrier, Laia Andreu‐Hayles, Mike Baillie, Claudia Baittinger, Niels Bleicher, Niels Bonde, David Brown, Marco Carrer, Richard J. Cooper, Katarina Čufar, Christoph Dittmar, Jan Esper, Carol B. Griggs, Björn E. Gunnarson, Björn Günther, Emília Gutiérrez, Kristof Haneca, Samuli Helama, Franz Herzig, Karl‐Uwe Heußner, Jutta Hofmann, Pavel Janda, Raymond Kontic, Nesıbe Köse, Tomáš Kyncl, Tom Levanič, Hans W. Linderholm, Sturt W. Manning, Thomas Melvin, Daniel Miles, Burkhard Neuwirth, Kurt Nicolussi, Paola Nola, Momchil Panayotov, Ionel Popa, Andreas Rothe, Kristina Seftigen, Andrea Seim, Helene Svarva, Miroslav Svoboda, Terje Thun, Mauri Timonen, Ramzi Touchan, Volodymyr Trotsiuk, Valérie Trouet, Felix Walder, Tomasz Ważny, Rob Wilson, Christian Zang,
Climate model projections suggest widespread drying in the Mediterranean Basin and wetting in Fennoscandia in the coming decades largely as a consequence of greenhouse gas forcing of climate. To place these and other "Old World" climate projections into historical perspective based on more complete estimates of natural hydroclimatic variability, we have developed the "Old World Drought Atlas" (OWDA), a set of year-to-year maps of tree-ring reconstructed summer wetness and dryness over Europe and the ...
Tópico(s): Hydrology and Drought Analysis
2015 - American Association for the Advancement of Science | Science Advances
Kristina Seftigen, Jesper Björklund, Edward R. Cook, Hans W. Linderholm,
Tópico(s): Plant Water Relations and Carbon Dynamics
2014 - Springer Science+Business Media | Climate Dynamics
Jesper Björklund, B. E. Gunnarson, Kristina Seftigen, Jan Esper, Hans W. Linderholm,
Abstract. Here we explore two new tree-ring parameters, derived from measurements of wood density and blue intensity (BI). The new proxies show an increase in the interannual summer temperature signal compared to established proxies, and present the potential to improve long-term performance. At high latitudes, where tree growth is mainly limited by low temperatures, radiodensitometric measurements of wood density, specifically maximum latewood density (MXD), provides a temperature proxy that is superior ...
Tópico(s): Forest ecology and management
2014 - Copernicus Publications | Climate of the past
Hans W. Linderholm, Peng Zhang, Björn E. Gunnarson, Jesper Björklund, Emad A. Farahat, Mauricio Fuentes, Eva Rocha, Riikka Salo, Kristina Seftigen, Petter Stridbeck, Yu Liu,
Trees growing at their altitudinal or latitudinal distribution in Fennoscandia have been widely used to reconstruct warm season temperatures, and the region hosts some of the world's longest tree-ring chronologies. These multi-millennial long chronologies have mainly been built from tree remains found in lakes (subfossil wood from lake-shore trees). We used a unique dataset of Scots pine tree-ring data collected from wood remains found on a mountain slope in the central Scandinavian Mountains, yielding ...
Tópico(s): Geology and Paleoclimatology Research
2014 - Frontiers Media | Frontiers in Ecology and Evolution
Jesper Björklund, Björn E. Gunnarson, Kristina Seftigen, Peng Zhang, Hans W. Linderholm,
The inexpensive Blue Intensity proxy has been considered a complement or surrogate to maximum latewood density (MXD), but is associated with biases from differential staining between sapwood and heartwood and also between deadwood samples and living-wood samples that compromise centennial-scale information. Here, we show that, with some minor adjustments, ΔBlue Intensity (ΔBI) is comparable with MXD or ΔDensity (Δ = the difference or contrast between latewood and earlywood density) in dendroclimatological ...
Tópico(s): Hydrology and Sediment Transport Processes
2014 - SAGE Publishing | The Holocene
Kristina Seftigen, Edward R. Cook, Hans W. Linderholm, Mauricio Fuentes, Jesper Björklund,
Abstract Moisture availability has been identified as one of the most important factors in the context of future climate change. This paper explores the potential of applying a multiproxy approach to dendroclimatology to infer the twentieth-century moisture variability over Fennoscandia. Fields of the warm-season (June–August) standardized precipitation evapotranspiration index (SPEI) were developed from a dense network of precipitation-sensitive annually resolved tree-ring width (TRW), maximum density ( ...
Tópico(s): Climate variability and models
2014 - American Meteorological Society | Journal of Climate
Hans W. Linderholm, Jesper Björklund, Kristina Seftigen, Björn E. Gunnarson, Mauricio Fuentes,
Despite the spatially homogenous summer temperature pattern in Fennoscandia, there are large spreads among the many existing reconstructions, resulting in an uncertainty in the timing and amplitude of past changes. Also, there has been a general bias towards northernmost Fennoscandia. In an attempt to provide a more spatially coherent view of summer (June–August, JJA) temperature variability within the last millennium, we utilized seven density and three blue intensity Scots pine (Pinus sylvestris ...
Tópico(s): Geology and Paleoclimatology Research
2014 - Springer Science+Business Media | Climate Dynamics
Kristina Seftigen, Hans W. Linderholm, Igor Drobyshev, Mats Niklasson,
ABSTRACT In this study, we present the first regional reconstruction of summer drought for southeastern Sweden. The June–July standardized precipitation index (SPI) was reconstructed over the period 1650–2002 based on Pinus sylvestris L. tree‐ring width data, where the reconstruction could account for 41.6% of the total variance in the instrumental record over 1901–2002. Our reconstruction suggests an overall wet 18th century and a dry 19th century. The most outstanding pluvial phase in the pre‐instrumental ...
Tópico(s): Climate variability and models
2012 - Wiley | International Journal of Climatology
Kristina Seftigen, Hans W. Linderholm, Neil J. Loader, Yu Liu, Giles Young,
The stable isotope composition of tree rings is known to contain valuable information of past climatic and environmental changes, which may be used as a complement to tree ring width and maximum latewood density in climate reconstructions. In this study we examine the character and strength of the climate signal captured in the delta O-18 and delta C-13 values of Scots pine (Pinus sylvestris L.) trees growing at the tree-line in the central Scandinavian Mountains. Between 4 and 14 trees were pooled ...
Tópico(s): Climate variability and models
2011 - Elsevier BV | Chemical Geology
Igor Drobyshev, Mats Niklasson, Hans W. Linderholm, Kristina Seftigen, Thomas Hickler, Ólafur Eggertsson,
We used a network of eight pedunculate oak ( Quercus robur L.) sites ( n trees = 70) and one Scots pine ( Pinus sylvestris L.) site ( n trees = 53) to develop drought-sensitive master chronologies for the two areas in southern Scandinavia: a SW-area centred on 57°N 12.7°E and a NE-area centred on 58.8°N 18.2°E. The ratio of actual to equilibrium evapotranspiration (AET/EET) was used as a measure of drought during the growing season defined as the period with average daily temperatures above 9°C. Instrumental ...
Tópico(s): Geology and Paleoclimatology Research
2011 - SAGE Publishing | The Holocene