A 4500-Year Tree-Ring Record of Extreme Climatic Events on the Yamal Peninsula

Based on the analysis of the frequency of anomalous anatomical structures in the wood of Siberian larch and Siberian spruce (frost rings, light rings, and false rings, as well as missing and narrow rings), we reconstructed a timeline of climatic extremes (summer frosts, sharp multiday decreases in air temperature during the growing season, and low average summer temperatures) in Yamal (Western Siberia) over the last 4500 years. In total, 229 years were determined to have experienced extreme events. The most significant temperature extremes were recorded in 2053, 1935, 1647, 1626, 1553, 1538, 1410, 1401, 982, 919, 883 BCE, 143, 404, 543, 640, 1209, 1440, 1453, 1466, 1481, 1601 and 1818 CE. These dates with extrema observed in Yamal corrobarated with tree ring data from other regions and revealed several coincidences. That is, in these years, the observed extremes appeared to have been on a global rather than a regional scale. Moreover, these dates coincided with traces of large volcanic eruptions found in ice cores from Greenland and Antarctica, dated to approximately the same years. Therefore, the cause of the extreme summer cooling on a global scale, in most cases, can be linked to large volcanic eruptions. © 2023 by the authors.Ministry of Education and Science of the Russian Federation, MinobrnaukaThe research funding from the Ministry of Science and Higher Education of the Russian Federation (Ural Federal University Program of Development within the Priority-2030 Program) is gratefully acknowledged

An 8768-year Yamal Tree-ring Chronology as a Tool for Paleoecological Reconstructions

Abstract—In recent years, the supra-long Yamal tree-ring chronology has been significantly extended and became much more reliable. This article characterizes the sample wood used to build the longest absolutely dated Siberian Larch tree-ring chronology of the Subarctic area, i.e. from 6748 BC to 2019 AD, for a total continuous period of 8768 years. The ecological value of the temporal and spatial distribution of the dated trees are presented, and their potential use for application in various field of natural sciences and humanities are discussed. © 2021, Pleiades Publishing, Ltd.This study was supported by the Russian Foundation for Basic Research (project no. 18-05-00575). P. Fonti thanks the Swiss Science Foundation for the financial support (project “CALDERA” no. CRSII5_183571)

Current Siberian heating is unprecedented during the past seven millennia

The Arctic is warming faster than any other region on Earth. Putting this rapid warming into perspective is challenging because instrumental records are often short or incomplete in polar regions and precisely-dated temperature proxies with high temporal resolution are largely lacking. Here, we provide this long-term perspective by reconstructing past summer temperature variability at Yamal Peninsula – a hotspot of recent warming – over the past 7638 years using annually resolved tree-ring records. We demonstrate that the recent anthropogenic warming interrupted a multi-millennial cooling trend. We find the industrial-era warming to be unprecedented in rate and to have elevated the summer temperature to levels above those reconstructed for the past seven millennia (in both 30-year mean and the frequency of extreme summers). This is undoubtedly of concern for the natural and human systems that are being impacted by climatic changes that lie outside the envelope of natural climatic variations for this region. © 2022, The Author(s).Natural Environment Research Council, NERC: NE/S015582/1; Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, SNF: 183571; Russian Foundation for Basic Research, РФФИ: 18-05-00575; Russian Science Foundation, RSF: 182398, 21-14-00330R.M.H., S.G.S., A.Y.S., and L.A.G. received funding from the Russian Foundation for Basic Research (no. 18-05-00575). M.S., C.C., S.G., and P.F. received funding from the SNF Sinergia project CALDERA (no. 183571). V.V.K. acknowledges support from the Russian Science Foundation (no. 21-14-00330). G.vA. acknowledges support from the SNF project XELLCLIM (no. 182398). T.J.O. acknowledges support from UK NERC project GloSAT (no. NE/S015582/1)

Minimum wood density of conifers portrays changes in early season precipitation at dry and cold Eurasian regions

Tracheids fulfil most wood functions in conifers (mechanical support and water transport) and earlywood tracheids account for most hydraulic conductivity within the annual tree ring. Dry conditions during the early growing season, when earlywood is formed, could lead to the formation of narrow tracheid lumens and a dense earlywood. Here, we assessed if there is a negative association between minimum wood density and early growing-season (spring) precipitation. Using dendrochronology, we studied growth and density data at nine forest stands of three Pinaceae species (Larix sibirica, Pinus nigra, and Pinus sylvestris) widely distributed in three cool–dry Eurasian regions from the forest-steppe (Russia, Mongolia) and Mediterranean (Spain) biomes. We measured for each annual tree ring and the common 1950–2002 period the following variables: earlywood and latewood width, and minimum and maximum wood density. As expected, dry early growing season (spring) conditions were associated with low earlywood production but, most importantly, to high minimum density in the three conifer species. The associations between minimum density and spring precipitation were stronger (r = -0.65) than those observed with earlywood width (r = 0.57). We interpret the relationship between spring water availability and high minimum density as a drought-induced reduction in lumen diameter, hydraulic conductivity, and growth. Consequently, forecasted growing-season drier conditions would translate into increased minimum wood density and reflect a reduction in hydraulic conductivity, radial growth, and wood formation. Given the case-study-like nature of this work, more research on other cold–dry sites with additional conifer species is needed to test if minimum wood density is a robust proxy of early season water availability

Minimum wood density of conifers portrays changes in early season precipitation at dry and cold Eurasian regions

Tracheids fulfil most wood functions in conifers (mechanical support and water transport) and earlywood tracheids account for most hydraulic conductivity within the annual tree ring. Dry conditions during the early growing season, when earlywood is formed, could lead to the formation of narrow tracheid lumens and a dense earlywood. Here, we assessed if there is a negative association between minimum wood density and early growing-season (spring) precipitation. Using dendrochronology, we studied growth and density data at nine forest stands of three Pinaceae species (Larix sibirica, Pinus nigra, and Pinus sylvestris) widely distributed in three cool–dry Eurasian regions from the forest-steppe (Russia, Mongolia) and Mediterranean (Spain) biomes. We measured for each annual tree ring and the common 1950–2002 period the following variables: earlywood and latewood width, and minimum and maximum wood density. As expected, dry early growing season (spring) conditions were associated with low earlywood production but, most importantly, to high minimum density in the three conifer species. The associations between minimum density and spring precipitation were stronger (r = -0.65) than those observed with earlywood width (r = 0.57). We interpret the relationship between spring water availability and high minimum density as a drought-induced reduction in lumen diameter, hydraulic conductivity, and growth. Consequently, forecasted growing-season drier conditions would translate into increased minimum wood density and reflect a reduction in hydraulic conductivity, radial growth, and wood formation. Given the case-study-like nature of this work, more research on other cold–dry sites with additional conifer species is needed to test if minimum wood density is a robust proxy of early season water availability

Arctic Greening Caused by Warming Contributes to Compositional Changes of Mycobiota at the Polar Urals

The long-term influence of climate change on spatio-temporal dynamics of the Polar mycobiota was analyzed on the eastern macro slope of the Polar Urals (Sob River valley and Mountain Slantsevaya) over a period of 60 years. The anthropogenic impact is minimal in the study area. Effects of environmental warming were addressed as changes in treeline and forest communities (greening of the vegetation). With warming, permafrost is beginning to thaw, and as it thaws, it decomposes. Therefore, we also included depth of soil thawing and litter decomposition in our study. Particular attention was paid to the reaction of aphyllophoroid fungal communities concerning these factors. Our results provide evidence for drastic changes in the mycobiota due to global warming. Fungal community composition followed changes of the vegetation, which was transforming from forest-tundra to northern boreal type forests during the last 60 years. Key fungal groups of the ongoing borealization and important indicator species are discussed. Increased economic activity in the area may lead to deforestation, destruction of swamps, and meadows. However, this special environment provides important services such as carbon sequestration, soil formation, protecting against flood risks, and filtering of air. In this regard, we propose to include the studied territory in the Polarnouralsky Natural Park

Climate change evidence in tree growth and stand productivity at the upper treeline ecotone in the Polar Ural Mountains

Abstract Background Recent warming is affecting species composition and species areal distribution of many regions. However, although most treeline studies have estimated the rates of forest expansion into tundra, still little is known about the long-term dynamic of stand productivity at the forest-tundra intersection. Here, we make use of tree-ring data from 350 larch (Larix sibirica Ledeb.) and spruce (Picea obovata Ledeb.) sampled along the singular altitudinal treeline ecotone at the Polar Urals to assess the dynamic of stand establishment and productivity, and link the results with meteorological observations to identify the main environmental drivers. Results The analysis of stand instalment indicated that more than 90% of the living trees appeared after 1900. During this period, the stand became denser and moved 50 m upward, while in recent decades the trees of both species grew faster. The maximum afforestation occurred in the last decades of the twentieth century, and the large number of encountered saplings indicates that the forest is still expanding. The upward shift coincided with a slight increase of May–August and nearly doubling of September–April precipitation while the increase in growth matched with an early growth season warming (June + 0.27 °C per decade since 1901). This increase in radial growth combined with the stand densification led to a 6–90 times increase of biomass since 1950. Conclusion Tree-ring based twentieth century reconstruction at the treeline ecotone shows an ongoing forest densification and expansion accompanied by an increased growth. These changes are driven by climate change mechanism, whereby the leading factors are the significant increase in May–June temperatures and precipitation during the dormant period. Exploring of phytomass accumulation mechanisms within treeline ecotone is valuable for improving our understanding of carbon dynamics and the overall climate balance in current treeline ecosystems and for predicting how these will be altered by global change

Modern Dynamics of High-Mountain Forests in the Northern Urals: Major Trends

На фоне наблюдаемого потепления климата во многих регионах отмечается смещение верхней и полярной границ распространения древесной растительности, изменение структуры и состава древостоев. Особый интерес вызывают регионы, растительность которых не испытывала масштабных антропогенных воздействий, что позволяет оценить естественную динамику древостоев. Данная работа посвящена изучению возрастной и морфологической структуры древесного яруса смешанных редколесий и лесов на восточном отроге хребта Молебный Камень (Северный Урал). В основу исследования положены методы пробных площадей и древесно-кольцевого анализа. В экотоне верхней границы древесной растительности отмечены существенные изменения состава, морфологической и возрастной структуры древостоев, произошедшие на фоне повышения летних температур и увеличения количества зимних осадков, наблюдаемых в данном районе со второй половины ХХ в. Анализ климатического отклика, содержащегося в четырех обобщенных древесно-кольцевых хронологиях, построенных по лиственнице сибирской, сосне сибирской, пихте сибирской и ели сибирской, показал, что на радиальный прирост изученных деревьев наибольшее влияние оказывают весенние и раннелетние условия произрастания. Полученные данные могут быть использованы при проведении лесохозяйственных и лесоустроительных работIn many regions climate warming has caused shifts of the upper and polar boundaries of woody vegetation and changes in the structure and composition of tree stands. Regions whose vegetation has not experienced large-scale anthropogenic impacts have attracted particular interest of researchers assessing the natural dynamics of stands. This work is devoted to the study of the age and morphological structure of the tree layer of mixed woodlands and forests on the Eastern spur of the Molebny Kamen’ ridge (Northern Urals). The study is based on the quadrat sampling method and tree-ring analysis. The tree-line ecotone shows significant changes in the composition and morphological and age structure of forest stands that have occurred in this region since the mid-twentieth century, with the rising summer temperatures and increasing winter precipitation. Climatic response analysis, contained in 4 generalized tree-ring chronologies constructed for the Siberian larch, Siberian pine, Siberian fir and Siberian spruce, suggests that radial growth of the trees is mostly influenced by spring and early summer growing conditions. The results of the study can be used in forestry and forest management activitie