Sunshine as culprit: It induces early spring physiological drought in dark coniferous (Pinus sibirica and Abies sibirica) alpine forest

Trees comprising high mountain forests have different requirements for site conditions (such as the water supply), thus current climate warming leads to varying reactions of upper forest boundaries depending on the site conditions and ecophysiological features of species. Positive reactions to an increasing heat supply during vegetative season may be hindered for drought-sensitive species by a water deficit in a cold environment, particularly during late winter or early spring. We investigated the radial growth of dark coniferous forest species Siberian stone pine (Pinus sibirica Du Tour) and Siberian fir (Abies sibirica Ledeb.) growing on slopes of different orientation (south-west, east, and north) near the upper forest boundary in an area undergoing fast climate warming: the Western Sayan Mountains (South Siberia, Russia), near a massive water reservoir. Correlations of tree-ring width chronologies with moving 21-day temperature series were used to more precisely determine the timing of temperature influence; an analysis of extreme and optimal years and multifactor regression modeling were applied to assess the most favorable/unfavorable thermal conditions in the study area and to estimate the tree growth reaction to the current climatic trends, respectively. Despite relatively low variation in growth (standard deviation <0.2), a significant common climatic signal in tree-ring width was found at all sampling sites. On the shaded northern slopes, P. sibirica is only mildly limited by summer temperatures and has a low similarity (correlations and synchronicity of extreme/optimal years) with other sites. Conversely, the growth of A. sibirica and P. sibirica on two sunlit slopes is similar (r = 0.44–0.81) and has a common pattern of regulation by temperatures before (r = −0.17…−80.40; April 3 – May 4 on average) and more significantly during vegetative season (r = 0.31…0.44; May 17 – August 27 on average). We hypothesize that both species, being drought-sensitive, undergo water stress in the early spring, and exposition of previous years’ needles to severe temperature variation may lead to partial defoliation and xylem embolism, thus suppressing growth. The patterns of climatic response and species distribution on slopes indicate that A. sibirica is more sensitive to this physiological drought and needs gentler slopes than P. sibirica. Temperature increase in the study area during the last decades have occured about five times faster in the early spring (being enhanced by the reservoir) than in summer. This combination of spring and summer warming leads to an increase in P. sibirica radial growth on the northern slope and the stable growth of both species on sunlit slopes, i.e. providing a tentatively optimistic assessment of the dark coniferous forests’ near future in the region

ЗАВИСИМОСТЬ ШИРИНЫ ГОДИЧНЫХ КОЛЕЦ СОСНЫ ОБЫКНОВЕННОЙ ОТ ТЕМПЕРАТУР ВОЗДУХА И ПОЧВЫВ ЛЕСОСТЕПНОЙ ЗОНЕ ЮГА СИБИРИ

Paper contains analysis of Scots pine (Pinussylvestris L.) radial growth response on annual fluctuations of temperature of air and soil at different depths in the forest-steppe zone of South Siberia. Effect of temperature on the radial growth was identified and explained. It is positive in the cold (November-February) and negative in the warm season (May-October). It was shown that in different months influence of temperatures at different depths is significant. This climate response in the forest steppe zone varies depending on the local conditions of the site.Проведен анализ климатического отклика радиального прироста сосны обыкновенной (PinussylvestrisL.) на погодичные колебания температуры воздуха и почвы на разных глубинах в лесостепной зонеЮга Сибири. Выявлено и объяснено влияние температур на радиальный прирост - положительное в холодный (ноябрь-февраль) и отрицательное в теплый период (май-октябрь). Показано, что в различные месяцы более значимо влияние температур на различных глубинах.Эта климатическая реакция в лесостепной зоне различается в зависимости от локальных условий места произрастания

Earlywood and Latewood Features of Pinus sylvestris in Semiarid Natural Zones of South Siberia

Chronologies of the anatomical and integral parameters of the Scots pine (Pinus sylvestris L.) earlywood and latewood were investigated for two sites in the Minusinsk depression with different soil moisture conditions. Patterns of statistical characteristics and climatic responses of the chronologies were identified. Differences between sites were revealed in the cell diameter and wall thickness distributions. These differences are indicators of adapting pine wood structure to the moisture deficit

Сlimatic Response of Conifer Radial Growth in Forest-Steppes of South Siberia: Comparison of Three Approaches

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.We compared three approaches to study climatic signals of Pinus sylvestris and Larix sibirica tree ring width chronologies from the forest-steppe zone of South Siberia, where both temperature and precipitation limit the conifer tree growth: 1—paired correlation of chronologies with monthly climatic variables; 2— paired and partial correlations with monthly and seasonal series of primary and secondary climatic factors, calculated in the Seascorr program; 3—paired correlation with a 15-day moving average series of climatic variables. The comparison showed that simple paired correlation with monthly series as the simplest approach could be used for a wide range of dendroclimatic studies, both as a main procedure and for preliminary analysis. The Seascorr analysis is the most suitable for assessing climate-growth relationship in extreme growth conditions and for reconstructions of extremes, e.g. droughts, and of their impact periods. The application of the 15-day moving average series is limited by availability of daily climatic data, but it describes the seasonal window of climatic response with high precision. Altogether, the combination of three approaches allowed to explore the spatial-temporal pattern of the conifers radial growth climatic response in South Siberia

The effect of individual genetic heterozygosity on general homeostasis, heterosis and resilience in Siberian larch (Larix sibirica Ledeb.) using dendrochronology and microsatellite loci genotyping

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.The genetic mechanisms underlying the relationship of individual heterozygosity (IndHet) with heterosis and homeostasis are not fully understood. Such an understanding, however, would have enormous value as it could be used to identify trees better adapted to environmental stress. Dendrochronology data, in particular the individual average radial increment growth of wood measured as the average tree ring width (AvTRW) and the variance of tree ring width (VarTRW) were used as proxies for heterosis (growth rate measured as AvTRW) and homeostasis (stability of the radial growth of individual trees measured as VarTRW), respectively. These traits were then used to test the hypothesis that IndHet can be used to predict heterosis and homeostasis of individual trees. Wood core and needle samples were collected from 100 trees of Siberian larch (Larix sibirica Ledeb.) across two populations located in Eastern Siberia. DNA samples were obtained from the needles of each individual tree and genotyped for eight highly polymorphic microsatellite loci. Then mean IndHet calculated based on the genotypes of eight loci for each tree was correlated with the statistical characteristics of the measured radial growth (AvTRW and VarTRW) and the individual standardized chronologies. The analysis did not reveal significant relationships between the studied parameters. In order to account for the strong dependence of the radial growth on tree age the age curves were examined. An original approach was employed to sort trees into groups based on the distance between these age curves. No relationship was found between these groups and the groups formed based on heterozygosity. However, further work with more genetic markers and increased sample sizes is needed to test this novel approach for estimating heterosis and homeostasis

Spatial classification of moisture-sensitive pine and larch tree-ring chronologies within Khakass–Minusinsk Depression, South Siberia

Key message: Growth patterns of Scots pine and Siberian larch under water deficit across an intermontane valley in South Siberia depend not only on landscape physiography but on species-specific climatic sensitivity and phenology. Abstract: The wide intermountain Khakass–Minusinsk Depression (KhMD) in southern Siberia presents an ideal setting for studying the potential impacts of a warming climate on forest ecosystems. The Centre of Continental Asia has one of the most intense rates of warming in the Northern Hemisphere, and the KhMD has multiple tree species of proven dendroclimatic value growing in drought-stressed environments. Investigation was aimed at spatial patterns of tree growth and its climate response across the KhMD for two main conifer species of moisture-deficient habitats, Scots pine (Pinus sylvestris L.) and Siberian larch (Larix sibirica Ledeb.). Correlation and cluster analysis were applied to a recently developed network of 15 tree-ring chronologies. Hierarchical classifications were based on the inter-chronology correlation matrix and on correlations of chronologies with monthly climate variables. Results underscore the general influence of hot-dry conditions on reducing growth and suggest a spatial grouping of chronologies governed by physiography and modified by species-dependent ecophysiological response to climate. Both applied classifications agree on the designation of geographically oriented clusters. A purely geographic grouping is broken, however, by species-specific climate dependence and phenology in deciduous Larix and evergreen Pinus. A differential ability to utilize melting snowpack in spring is advanced as a possible explanation for chronologies abandoning physiographically defined clusters. Such inter-species heterogeneity can manifest itself in the intensity of the climate change impact on vegetation, and lead to prospects of significant species composition changes in ecosystems.Ministry of Science and Higher Education12 month embargo; published: 12 August 2021This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

The effect of individual genetic heterozygosity on general homeostasis, heterosis and resilience in Siberian larch (Larix sibirica Ledeb.) using dendrochronology and microsatellite loci genotyping

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.The genetic mechanisms underlying the relationship of individual heterozygosity (IndHet) with heterosis and homeostasis are not fully understood. Such an understanding, however, would have enormous value as it could be used to identify trees better adapted to environmental stress. Dendrochronology data, in particular the individual average radial increment growth of wood measured as the average tree ring width (AvTRW) and the variance of tree ring width (VarTRW) were used as proxies for heterosis (growth rate measured as AvTRW) and homeostasis (stability of the radial growth of individual trees measured as VarTRW), respectively. These traits were then used to test the hypothesis that IndHet can be used to predict heterosis and homeostasis of individual trees. Wood core and needle samples were collected from 100 trees of Siberian larch (Larix sibirica Ledeb.) across two populations located in Eastern Siberia. DNA samples were obtained from the needles of each individual tree and genotyped for eight highly polymorphic microsatellite loci. Then mean IndHet calculated based on the genotypes of eight loci for each tree was correlated with the statistical characteristics of the measured radial growth (AvTRW and VarTRW) and the individual standardized chronologies. The analysis did not reveal significant relationships between the studied parameters. In order to account for the strong dependence of the radial growth on tree age the age curves were examined. An original approach was employed to sort trees into groups based on the distance between these age curves. No relationship was found between these groups and the groups formed based on heterozygosity. However, further work with more genetic markers and increased sample sizes is needed to test this novel approach for estimating heterosis and homeostasis

Anopheles mosquitoes reveal new principles of 3D genome organization in insects.

Chromosomes are hierarchically folded within cell nuclei into territories, domains and subdomains, but the functional importance and evolutionary dynamics of these hierarchies are poorly defined. Here, we comprehensively profile genome organizations of five Anopheles mosquito species and show how different levels of chromatin architecture influence each other. Patterns observed on Hi-C maps are associated with known cytological structures, epigenetic profiles, and gene expression levels. Evolutionary analysis reveals conservation of chromatin architecture within synteny blocks for tens of millions of years and enrichment of synteny breakpoints in regions with increased genomic insulation. However, in-depth analysis shows a confounding effect of gene density on both insulation and distribution of synteny breakpoints, suggesting limited causal relationship between breakpoints and regions with increased genomic insulation. At the level of individual loci, we identify specific, extremely long-ranged looping interactions, conserved for ~100 million years. We demonstrate that the mechanisms underlying these looping contacts differ from previously described Polycomb-dependent interactions and clustering of active chromatin