Author Correction: Limited capacity of tree growth to mitigate the global greenhouse effect under predicted warming.

An amendment to this paper has been published and can be accessed via a link at the top of the paper

Contribution of xylem anatomy to tree-ring width of two larch species in permafrost and non-permafrost zones of Siberia

Plants exhibit morphological and anatomical adaptations to cope the environmental constraints of their habitat. How can mechanisms for adapting to contrasting environmental conditions change the patterns of tree rings formation? In this study, we explored differences in climatic conditions of permafrost and non-permafrost zones and assessed their influence on radial growth and wood traits of Larix gmelinii Rupr (Rupr) and Larix sibirica L., respectively. We quantified the contribution of xylem cell anatomy to the tree-ring width variability. Comparison of the anatomical tree-ring parameters over the period 1963–2011 was tested based on non-parametric Mann-Whitney U test. The generalized linear modeling shows the common dependence between TRW and the cell structure characteristics in contrasting environments, which can be defined as non-specific to external conditions. Thus, the relationship between the tree-ring width and the cell production in early- and latewood are assessed as linear, whereas the dependence between the radial cell size in early- and latewood and the tree-ring width becomes significantly non-linear for both habitats. Moreover, contribution of earlywood (EW) and latewood (LW) cells to the variation of TRW (in average 56.8% and 24.4% respectively) was significantly higher than the effect of cell diameters (3.3% (EW) and 17.4% (LW)) for the environments. The results show that different larch species from sites with diverging climatic conditions converge towards similar xylem cell structures and relationships between xylem production and cell traits. The work makes a link between climate and tree-ring structure, and promotes a better understanding the anatomical adaptation of larch species to local environment conditions

Comparing Forest Measurements from Tree Rings and a Space-Based Index of Vegetation Activity in Siberia

Different methods have been developed for measuring carbon stocks and fluxes in the northern high latitudes, ranging from intensively measured small plots to space-based methods that use reflectance data to drive production efficiency models. The field of dendroecology has used samples of tree growth from radial increments to quantify long-term variability in ecosystem productivity, but these have very limited spatial domains. Since the cambium material in tree cores is itself a product of photosynthesis in the canopy, it would be ideal to link these two approaches. We examine the associations between the normalized differenced vegetationindex (NDVI) and tree growth using 19 pairs of tree-ring widths (TRW) and maximum latewood density (MXD) across much ofSiberia. We find consistent correlations between NDVI and both measures of tree growth and no systematic difference between MXD and TRW. At the regional level we note strong correspondence between the first principal component of tree growth and NDVI for MXD and TRW in a temperature-limited bioregion, indicating that canopy reflectance and cambial production are broadly linked. Using a network of 21 TRW chronologies from south of Lake Baikal, we find a similarly strong regional correspondence with NDVI in a markedly drier region. We show that tree growth is dominated by variation at decadal and multidecadal time periods, which the satellite record is incapable of recording given its relatively short record

Prominent role of volcanism in Common Era climate variability and human history

Climate reconstructions for the Common Era are compromised by the paucity of annually-resolved and absolutely-dated proxy records prior to medieval times. Where reconstructions are based on combinations of different climate archive types (of varying spatiotemporal resolution, dating uncertainty, record length and predictive skill), it is challenging to estimate past amplitude ranges, disentangle the relative roles of natural and anthropogenic forcing, or probe deeper interrelationships between climate variability and human history. Here, we compile and analyse updated versions of all the existing summer temperature sensitive tree-ring width chronologies from the Northern Hemisphere that span the entire Common Era. We apply a novel ensemble approach to reconstruct extra-tropical summer temperatures from 1 to 2010 CE, and calculate uncertainties at continental to hemispheric scales. Peak warming in the 280s, 990s and 1020s, when volcanic forcing was low, was comparable to modern conditions until 2010 CE. The lowest June–August temperature anomaly in 536 not only marks the beginning of the coldest decade, but also defines the onset of the Late Antique Little Ice Age (LALIA). While prolonged warmth during Roman and medieval times roughly coincides with the tendency towards societal prosperity across much of the North Atlantic/European sector and East Asia, major episodes of volcanically-forced summer cooling often presaged widespread famines, plague outbreaks and political upheavals. Our study reveals a larger amplitude of spatially synchronized summer temperature variation during the first millennium of the Common Era than previously recognised

Scientific merits and analytical challenges of tree-ring densitometry

R.W. was supported by NERC grant NE/K003097/1.X-ray microdensitometry on annually-resolved tree-ring samples has gained an exceptional position in last-millennium paleoclimatology through the maximum latewood density parameter (MXD), but also increasingly through other density parameters. For fifty years, X-ray based measurement techniques have been the de facto standard. However, studies report offsets in the mean levels for MXD measurements derived from different laboratories, indicating challenges of accuracy and precision. Moreover, reflected visible light-based techniques are becoming increasingly popular and wood anatomical techniques are emerging as a potentially powerful pathway to extract density information at the highest resolution. Here we review the current understanding and merits of wood density for tree-ring research, associated microdensitometric techniques, and analytical measurement challenges. The review is further complemented with a careful comparison of new measurements derived at 17 laboratories, using several different techniques. The new experiment allowed us to corroborate and refresh ?long-standing wisdom?, but also provide new insights. Key outcomes include; i) a demonstration of the need for mass/volume based re-calibration to accurately estimate average ring density; ii) a substantiation of systematic differences in MXD measurements that cautions for great care when combining density datasets for climate reconstructions; and iii) insights into the relevance of analytical measurement resolution in signals derived from tree-ring density data. Finally, we provide recommendations expected to facilitate future inter-comparability and interpretations for global change research.Publisher PDFPeer reviewe

Global wood anatomical perspective on the onset of the Late Antique Little Ice Age (LALIA) in the mid-6th century CE

Linked to major volcanic eruptions around 536 and 540 CE, the onset of the Late Antique Little Ice Age has been described as the coldest period of the past two millennia. The exact timing and spatial extent of this exceptional cold phase are, however, still under debate because of the limited resolution and geographical distribution of the available proxy archives. Here, we use 106 wood anatomical thin sections from 23 forest sites and 20 tree species in both hemispheres to search for cell-level fingerprints of ephemeral summer cooling between 530 and 550 CE. After cross-dating and double-staining, we identified 89 Blue Rings (lack of cell wall lignification), nine Frost Rings (cell deformation and collapse), and 93 Light Rings (reduced cell wall thickening) in the Northern Hemisphere. Our network reveals evidence for the strongest temperature depression between mid-July and early-August 536 CE across North America and Eurasia, whereas more localised cold spells occurred in the summers of 532, 540–43, and 548 CE. The lack of anatomical signatures in the austral trees suggests limited incursion of stratospheric volcanic aerosol into the Southern Hemisphere extra-tropics, that any forcing was mitigated by atmosphere-ocean dynamical responses and/or concentrated outside the growing season, or a combination of factors. Our findings demonstrate the advantage of wood anatomical investigations over traditional dendrochronological measurements, provide a benchmark for Earth system models, support cross-disciplinary studies into the entanglements of climate and history, and question the relevance of global climate averages. © 2022 Science China PressFritz & Elisabeth Schweingruber FoundationNational Science Foundation, NSF, (1203749, 1902625, 2002454, 2112314, 2124885, RSF 18-14-00072P, RSF 21-14-00330)Engineering Research Centers, ERCEuropean Research Council, ERC, (AdG 882727, CZ.02.1.01/0.0/0.0/16_019/0000797)Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, SNF, (CRSII5 183571)Fondo Nacional de Desarrollo Científico y Tecnológico, FONDECYT, (1201411, 1221307)Vetenskapsrådet, VR, (2018-01272)Universität BielefeldRussian Science Foundation, RSF, (RSF 21-17-00006)Fondo de Financiamiento de Centros de Investigación en Áreas Prioritarias, FONDAP, (15110009, BASAL FB210018)Neurosciences Foundation, NSFAgencia Nacional de Investigación y Desarrollo, ANIDFunding text 1: Ulf Büntgen and Jan Esper received funding from the ERC Advanced Project MONOSTAR (AdG 882727). Ulf Büntgen, Jan Esper, and Mirek Trnka received funding from SustES: adaptation strategies for sustainable ecosystem services and food security under adverse environmental conditions (CZ.02.1.01/0.0/0.0/16_019/0000797). Ulf Büntgen, Jan Esper, and Clive Oppenheimer discussed many aspects of this study at the Center for Interdisciplinary Research (ZiF) at the University of Bielefeld, Germany. Alan Crivellaro received funding from the Fritz & Elisabeth Schweingruber Foundation. Duncan A. Christie and Carlos Le Quesne received funding from the ANID (FONDECYT 1201411, 1221307, FONDAP 15110009, BASAL FB210018). Olga V. Churakova (Sidorova) received funding from the Russian Science Foundation grant (RSF 21-17-00006). Rosanne D'Arrigo received funding from NSF Arctic Social Science 2112314 and NSF Arctic Natural Science 2124885, as well as the NSF P2C2 (Paleo Perspectives on Climatic Change) program (various grants). Rashit M. Hantemirov received funding from the Russian Science Foundation grant (RSF 21-14-00330). Alexander V. Kirdyanov received funding from the Russian Science Foundation grant (RSF 18-14-00072P). Fredrik C. Ljungqvist was supported by the Swedish Research Council (2018-01272). Patrick Fonti and Markus Stoffel received funding from the Swiss National Science Foundation through the SNSF Sinergia CALDERA project (CRSII5 183571). Matthew Salzer and Malcolm K. Hughes received funding from the National Science Foundation's P2C2 Program (1902625 and 1203749) and from the Malcolm H. Wiener Foundation. Greg Wiles was funded through NSF P2C2 Program (2002454). Ulf Büntgen designed the study and wrote the first draft of this manuscript with input from Jan Esper, Paul J. Krusic, and Clive Oppenheimer. Samples were processed and analysed by Alma Piermattei and Alan Crivellaro. All authors provided data and/or contributed to discussion and improving the article.Funding text 2: Ulf Büntgen and Jan Esper received funding from the ERC Advanced Project MONOSTAR (AdG 882727). Ulf Büntgen, Jan Esper, and Mirek Trnka received funding from SustES : adaptation strategies for sustainable ecosystem services and food security under adverse environmental conditions (CZ.02.1.01/0.0/0.0/16_019/0000797). Ulf Büntgen, Jan Esper, and Clive Oppenheimer discussed many aspects of this study at the Center for Interdisciplinary Research (ZiF) at the University of Bielefeld, Germany. Alan Crivellaro received funding from the Fritz & Elisabeth Schweingruber Foundation . Duncan A. Christie and Carlos Le Quesne received funding from the ANID ( FONDECYT 1201411 , 1221307, FONDAP 15110009 , BASAL FB210018). Olga V. Churakova (Sidorova) received funding from the Russian Science Foundation grant ( RSF 21-17-00006 ). Rosanne D’Arrigo received funding from NSF Arctic Social Science 2112314 and NSF Arctic Natural Science 2124885 , as well as the NSF P2C2 (Paleo Perspectives on Climatic Change) program (various grants). Rashit M. Hantemirov received funding from the Russian Science Foundation grant (RSF 21-14-00330). Alexander V. Kirdyanov received funding from the Russian Science Foundation grant (RSF 18-14-00072P). Fredrik C. Ljungqvist was supported by the Swedish Research Council (2018-01272). Patrick Fonti and Markus Stoffel received funding from the Swiss National Science Foundation through the SNSF Sinergia CALDERA project (CRSII5 183571). Matthew Salzer and Malcolm K. Hughes received funding from the National Science Foundation’s P2C2 Program (1902625 and 1203749) and from the Malcolm H. Wiener Foundation . Greg Wiles was funded through NSF P2C2 Program (2002454)