Induction of discolored wood in Scots pine (Pinus sylvestris).

Наведені результати обстеження насаджень сосни чорної австрійської в Кіровоградській, Харківській і Сумській областях у 2017 та 2018 рр. В умовах Лісостепу та Степу досліджено 4 деревостани віком 27–117 років, лісові культури 27-річного віку є потомством найстарішого з обстежених деревостанів. Оцінювання насаджень проведено за ростом, якістю стовбурів, станом, а також показниками репродукції. Для комплексного оцінювання деревостанів використано 3-балову шкалу. В усіх обстежених насадженнях сосна чорна поступається сосні звичайній за висотою, але у 2 із 5 випадків перевищує її за діаметром; характеризується стовбурами більшої якості та кращім станом. За результатами комплексного оцінювання сосна чорна австрійська набрала більшу або таку саму кількість балів, як і сосна звичайна. Підтверджено перспективність застосування сосни чорної для створення лісових і захисних насаджень на еродованих ґрунтах. У разі помірного рекреаційного навантаження вона спроможна виконувати меліоративні функції, а завдяки своїй високій декоративності придатна для садово-паркового будівництва.

This study compared the strength properties of wood taken from Sitka spruce (Picea sitchensis (Bong.) Carr.) and Scots pine (Pinus sylvestris L.) trees damaged as a result of wind and snow. The spruce trees were located in triplets of stems of similar diameter that had snapped, overturned (i.e., uprooted), or remained undamaged as a result of wind and snow. The pine trees were located in pairs of similar-sized stems that had snapped or remained undamaged. None of the pine trees overturned. Clear wood (wood without knots and sloping grain) from the outer part of the stem of snapped Sitka spruce and Scots pine trees was less stiff (lower modulus of elasticity (MOE)) than wood taken from the same location from overturned (spruce only) or standing trees. Modulus of rupture and density were unaffected. Damaged trees of both species were found to have significantly more compression wood within the test samples in comparison with undamaged trees. These findings suggest that trees that either overturn or snap are bending more than undamaged trees (because of their low MOE) thereby introducing a greater component of crown weight to the overall forces acting on the stem, and that this may be associated with compression wood.

The Scots Pine Pinus sylvestris is the most widespread tree species in forests of lowland parts of Central and Eastern Europe. In Polish forests, stands dominated by the Scots pine cover almost 60% of the forest area. We analysed the relationship between forest birds and pine trees in an extensive forest complex in north-eastern (NE) Poland. Based on the 20-year-long study, we considered the percentage of broods established on pine trees and the percentage of Scots pine in stands on grouse leks and territory. A total number of over 20 bird species are dependent on the Scots pine trees or stands to locate their nests. Among this group, 11 bird species strongly associated with pine trees were confirmed, and they located at least 90% of broods or nests on pines. The Black Woodpecker Dryocopus martius selects the Scots pine to excavate cavities. Its cavities were regularly used by some species of secondary cavity nesters. In turn, the Common Raven Corvus corax nests were occupied by selected birds of prey. The importance of Scots pine for birds increased with the age of the trees. Old Scots pine trees were chosen by birds that built large nests, placed nests in the tree top, and excavated large cavities. Populations of pine-specialized bird species may be in danger due to the possibility of the Scots pine range moving to the north, which results from global warming. The maintenance of the Scots pine with the modification of the methods of forest regeneration should be included in the Polish forestry’s strategies and plans as a critical factor for the care of the population of rare breeding bird species.

The aim of the research has been to study the features of the annual increment of shoots of Scots pine (Pinus sylvestris L.) trees depending on the hydrothermal regime of the air environment in the conditions of the city of Omsk. The subject of the study has been the analysis of shoot growth during the growing season. The nature of the hydrothermal regime is considered by constructing climatic diagrams according to Gossen–Walter based on data from the agrometeorological bulletins of the Omsk hydrometeorological centre from 1960 to the present day for May. The features of the dynamics of annual shoot increment in Scots pine trees have been studied at 3 different sites in the city of Omsk. The characteristics of the considered areas of pine crops have been presented, and the patterns of annual increment of shoots of model trees have been described. An analysis of the synchronicity of annual increment of model trees according to S.G. Shiyatov has been carried out. As a result of the correlation analysis using the moving average method, a moderate relationship has been found between the annual increment and the air temperature for May–June in all areas; a moderate relationship with the amount of precipitation for May and May–June has been obtained only for one area. According to climatic diagrams, over the past 30 years, the frequency of wet periods in May has increased, while their duration has decreased. In addition, very low correlation coefficients have been established between the annual increment of pine trees and temperatures and precipitation over the studied months of the growing season, which confirms the absence of linear relationship between them. The research materials can be useful in organizing work on the care of Scots pine plantations and developing theoretical foundations for the production of pine crops in urban conditions.

We determined effects of long-term elevation of carbon dioxide concentration ([CO2]) and temperature on growth, respiration and carbohydrate concentration in needles of field-grown Scots pine (Pinus sylvestris L.) trees during the needle expansion period. Sixteen 20-year-old Scots pine trees were individually enclosed in closed-top, environmentally controlled chambers for 4 years in one of four environments: ambient conditions (CON); elevated [CO2] (EC); elevated temperature (ET); and a combination of both (EC + ET). Needle growth, carbohydrate concentration and dark respiration were measured at 3-day intervals throughout the needle expansion period. Dark respiration was partitioned into growth and maintenance components by regressing specific respiration rate against specific growth rate. In all treatments, growth, carbohydrate concentration and daily dark respiration rates of needles followed a similar seasonal pattern throughout the needle expansion period. Treatments EC, ET and EC + ET increased individual needle area and dry weight compared with the CON treatment. Carbohydrate concentrations in needles were increased by EC, but reduced by ET and EC + ET. Daily respiration rates increased slightly in the early stage of needle expansion and decreased gradually in the late stage when needles were exposed to EC, but increased consistently throughout the growing period when needles were exposed to ET or EC + ET. Partitioning of respiration into its two functional components showed that the growth respiration coefficient was unaffected by the treatments, whereas maintenance respiration was reduced by EC but increased by ET and EC + ET. Maintenance respiration was more sensitive to elevated temperature than growth respiration. We conclude that the difference in respiration rates between expanding and expanded needles should be taken into account when estimating the respiratory responses of needles to elevated [CO2] and temperature.

Scots pine (Pinus sylvestris) is the most widespread pine species in the world. It is a major tree species found in the northern hemisphere and in large parts of the boreal forest. In recent studies, birch trees, another notable species in the boreal forest, have been identified as an important emission source of ice-nucleating macromolecules (INMs). The INMs were found in pollen1 and all over the tree’s tissue (e.g., branch wood, bark, petioles, and leaves)2,3. Similarly, Scots pine pollen were found to be ice nucleation active, but until now, no further investigation of INMs from other tissue types has been conducted.In this laboratory and field study, we collected samples from six different Scots pine trees in urban parks in Vienna, Austria. We investigated the distribution of INMs among three different tissue types, namely bark, branch wood, and needles, by extracting them from the milled sample (as a bulk sample) and the surface of the intact tissue and measuring ice nucleation activity in immersion freezing mode. We aimed to quantify the overall INM content of this species and assume it is independent of the growing region, as previously reported for birch trees, allowing us to extrapolate our results to the vast locations where Scots pines are found. In addition, we investigated the ability of rain events to wash the INMs off trees in a field study. We found INMs in all samples with freezing onset temperatures ranging from -16°C to -29°C. The bulk samples showed INM concentrations ranging from 105 to 109 per mg dry weight active at -25°C and higher. In surface extracts from the intact tissue, we found concentrations from 105 to 108 INMs per cm2 of the extracted surface. Most importantly, we found all rain samples to contain INMs with similar freezing onset temperatures to the lab extracts.On the basis of our results, we estimate that one square meter of Scots pine stand has the potential to release about 109 to 1012 INMs active at -25°C or higher. This estimation reveals pine trees as a massive reservoir of INMs. Boreal forests containing large numbers of birch and pine trees must be considered an essential source of atmospheric INMs. We propose Scots pine as an important emission source of INMs, nucleating ice in immersion freezing mode at moderate supercooled temperatures and thereby impacting the microphysics of mixed-phase clouds.  (1)          Pummer, B. G.; Bauer, H.; Bernardi, J.; Bleicher, S.; Grothe, H. Suspendable Macromolecules Are Responsible for Ice Nucleation Activity of Birch and Conifer Pollen. Atmospheric Chemistry and Physics 2012, 12 (5). https://doi.org/10.5194/acp-12-2541-2012.(2)          Felgitsch, L.; Baloh, P.; Burkart, J.; Mayr, M.; Momken, M. E.; Seifried, T. M.; Winkler, P.; Schmale, D. G.; Grothe, H. Birch Leaves and Branches as a Source of Ice-Nucleating Macromolecules. Atmospheric Chemistry and Physics 2018, 18 (21). https://doi.org/10.5194/acp-18-16063-2018.(3)          Seifried, T. M.; Bieber, P.; Felgitsch, L.; Vlasich, J.; Reyzek, F.; Schmale, D. G.; Grothe, H. Surfaces of Silver Birch (Betula Pendula) Are Sources of Biological Ice Nuclei: In Vivo and in Situ Investigations. Biogeosciences 2020, 17 (22). https://doi.org/10.5194/bg-17-5655-2020.

The object of this study was to investigate the effect of pruning on heartwood formation in mature Scots pine (Pinus sylvestris L.) trees. Fifty trees were treated by three different intensive pruning regimes: 42, 60 and 70 percentage of defoliation. After five growing seasons numbers of growth rings were counted and the width and the area of sapwood and heartwood were calculated. The results did not show any proportional increase or decrease in the heartwood area or in the number of growth rings in heartwood associated with the pruning. A statistically significant negative effect of pruning was found on the width of the five most recently formed sapwood growth rings. This decreased growth rate did not influence the ratio of sapwood and heartwood. However, it cannot be excluded that the proportion of heartwood may increase during a longer period. It is concluded that pruning is not a practicable silvicultural method for regulating heartwood formation in mature Scots pine trees.

Hormonal responses to short-term and long-term water deficit in native Scots pine and Norway spruce trees

Photosynthesis in evergreen conifers is characterized by down-regulation in autumn and rapid up-regulation in spring. This seasonal pattern is largely driven by temperature, but the light environment also plays a role. In overwintering Scots pine (Pinus sylvestris L.) trees, PSII is less down-regulated and recovers faster from winter stress in shaded needles than in needles exposed to full sunlight. Because the effect of light on the seasonal acclimation of PSII has not been quantitatively studied under field conditions, we used the rate constants for sustained thermal energy dissipation and photochemistry to investigate the dynamics and kinetics of the seasonal acclimation of PSII in needles exposed to different light environments. We monitored chlorophyll fluorescence and needle pigment concentration during the winter and spring in Scots pine seedlings growing in the field in different shading treatments, and within the crowns of mature trees. The results indicated that differences in acclimation of PSII in overwintering Scots pine among needles exposed to different light environments can be chiefly attributed to sustained thermal dissipation. We also present field evidence that zeaxanthin-facilitated thermal dissipation and aggregation of thylakoid membrane proteins are key mechanisms in the regulation of sustained thermal dissipation in Scots pine trees in the field.

Morphological characteristics of beeted Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) trees grown under differing influence from neighbouring trees were compared. The shape of Scots pine trees showed greater plasticity in response to competition than that of Norway spruce trees. When compared at the same height, Scots pine trees growing under strong influence from neighbours had smaller stem volumes and branch basal areas, shorter branches and decreased number of current shoots compared to Scots pine trees growing under weak influence from their neighbours. In Norway spruce, the only characteristic that was significantly affected by competition was the number of current shoots.

The seasonal changes in a period of low temperatures and characteristic correlations of some antioxidant system (AOS) components in pine needles influenced by a gas flare are investigated in this study. The parameters taken are total water content (TWC) in needles, peroxidase activity (AP) and selected elements of the antioxidant system of needles, such as content of carotenoids (Car), ascorbic acid (AA), catechins (Cat) and flavanols (Fl). The needles come from Scots pine trees (Pinus sylvestris L.), which grow in a gradient of environmental conditions formed in the zone of thermal field of the gas flare impact (at various distances). The gas flare is situated on the territory of the Khanty-Mansiysk Autonomous Okrug (UGRA) of Russia. Three hypotheses were subject to verification: 1) the thermal field of the gas flare during the low temperature period affects the water exchange and the AOS state of needles; 2) increase in temperature of the environment in the flare impact zone during the autumn-winter period causes the decrease in amount of moisture in needles, which is a trait of oxidative stress in cells; 3) in the functioning of а needle’s AOS, there are correlations between its components, which values depend on distance from the gas flare and environment created by it. It was found that in the thermal field gradient of the flare, there is neither an additional reduction in TWC in needles compared to the background nor signs of change in the state of AOS corresponding to the oxidative stress in the cells. The greatest impact of the gas flare on characteristics of the physiological state of pine needles is observed in the section closest to the flare. It reveals in the higher values of AP, TWC, Car and decrease in concentration of Fl and AA. The seasonal dynamics of the studied traits values do not correlate with the temperature of the environment. It indicates the indirect effect on the regulation of needle’s AOS activity. The factor and correlation analysis of the data indicate a difference in physiological state of pine needles at different distances from the flare. There is no domination of any processes in the functioning of AOS components. The observed correlations between the studied properties change according to distance to the flare. The most stable is a negative AP relationship with ofter parameters, which rise with the increased distance from the flare. The consistency degree of separate AOS components functioning is maximal in background conditions and decreases when approaching the flare. This fact is explained by the modifying effect of the flare on physiological and biochemical processes of the needle’s adaptation to specific climatic conditions of the environment. For citation: Shavnin S.A., Yusupov I.A., Montile A.A., Golikov D.Yu., Marina N.V. Seasonal Dynamics of Content of Antioxidant System Components in Needles of Scots Pine (Pinus sylvestris L.) Trees Situated in the Local Warming Impact Zone. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 2, pp. 38–57. (In Russ.). https://doi.org/10.37482/0536-1036-2023-2-38-57

ABSTRACTTo resolve an inconsistency around AD 1895 between radiocarbon (14C) measurements on oak from the British Isles and Douglas fir and Sitka spruce from the Pacific Northwest, USA, we measured the 14C content in single-year tree rings from a Scots pine tree (Pinus sylvestris L.), which grew in a remote location in Saltdal, northern Norway. The dataset covers the period AD 1864–1937 and its results are in agreement with measurements from the US Pacific coast around 1895. The most likely explanation for older ages in British oak in this period seems to be 14C depletion associated with the combustion of fossil fuels.

Effect of heavy metal pollution on the wood structure and tracheid characteristics in Scots pine treesfrom flotation tailings. Numerous studies have demonstrated the negative impact of heavy metals on plants, suchas inhibited growth and other physiological disturbances. However, the detailed structure of wood cells in treesexposed to heavy metal pollution remains underexplored. To address this gap, several Scots pine (Pinussylvestris L.) trees growing on flotation tailings was selected to compare the wood structure of trees affectedby severe heavy metal pollution with those from a relatively unpolluted area. Tree ring structure, wood density,and the cell wall and lumen characteristics of earlywood and latewood tracheids were analysed. It has been foundthat tracheid diameters and cell wall thicknesses in wood from the polluted area differed significantly from thosein the control samples. The wood of trees growing on flotation tailings exhibited slightly lower wood density thanthat of reference trees. This might be connected with the observed thinner cell walls in latewood tracheids of pinesaffected by heavy metals, compared to the reference material. Overall, considerably greater variation in mostmeasured parameters were observed for wood samples from flotation tailings than for the control samples.

Key messageAn exceptionally high number of blue rings were formed within and between Scots pine trees from Estonia in 1976: a year that is well known for its outstanding summer heatwave over Western Europe, but its extreme autumnal cooling over Eastern Europe has so far been neglected in scientific literature.‘Blue rings’ (BRs) are visual indicators of less lignified cell walls typically formed towards the end of a tree’s growing season. Though BRs have been associated with ephemeral surface cooling, often following large volcanic eruptions, the intensity of cold spells necessary to produce BRs, as well as the consistency of their formation within and between trees still remains uncertain. Here, we report an exceptionally high BR occurrence within and between Scots pine (Pinus sylvestris L.) trees at two sites in Estonia, including the first published whole-stem analysis for BRs. Daily meteorological measurements from a nearby station allowed us to investigate the role temperature has played in BR formation since the beginning of the twentieth century. The single year in which BRs were consistently formed within and amongst most trees was 1976. While the summer of 1976 is well known for an exceptional heatwave in Northwest Europe, mean September and October temperatures were remarkably low over Eastern Europe, and 3.8 °C below the 1961–1990 mean at our sites. Our findings contribute to a better eco-physiological interpretation of BRs, and further demonstrate their ability to reveal ephemeral cooling not captured by dendrochronological ring width and latewood density measurements.

Tree growth is a key indicator of forest health and development, especially in the context of a changing climate. Interactions between abiotic and biotic factors influencing tree growth are highly complex, with their full magnitude still unknown. Even trees of the same species and within the same forest can present high variability in their growth, as they are affected by various macro- and micro-scale factors. In order to detect and quantify tree growth at tree level, close-range monitoring with high spatial and temporal resolutions is required. For this purpose, LiDAR (Light Detection and Ranging) data is widely recognized for its ability to produce high-resolution point clouds, which enable studying intricate changes in trees.  The goal of our study is to explore the potential of daily LiDAR time-series for detecting the onset of tree height growth and quantifying the total growth in tree height, to help understand the biotic and abiotic factors contributing to height growth variability in Scots pine (Pinus sylvestris) trees. Here, we studied 97 Scots pine trees during the growing season of 2021 with dense spatiotemporal point cloud time series collected with LiDAR Phenology Station (LiPhe) in Hyytiälä forest research station, Finland. We developed a semi-automatic framework to extract individual tree height time-series, which includes point cloud registration, point cloud segmentation, and tree height estimation. Based on extracted height time-series derived from LiPhe, we detected the onset of tree height growth using a change point detection algorithm.   We found up to 28 days of variability in the onset of height growth within the studied Scots pine trees. To investigate the factors influencing the variability in the onset of height growth, we used tree size, neighborhood characteristics, and topography as explanatory variables in a linear mixed-effects model. These variables were also estimated from LiDAR data. The best performing model for modelling the onset of growth combined Plant Area Index (PAI), Vertical Complexity Index (VCI), and Topographic Wetness Index (TWI), as fixed-effect terms.   Our results suggest that higher density and complexity of neighboring trees leads to earlier onset of tree height growth, which can suggest competition for light and microclimate variability. Meanwhile, lower TWI led to earlier onset of tree height growth, indicating that trees located on a slightly higher slope with less water availability grew earlier in height. Lower areas may have a cooler microclimate, since they often retain more soil moisture and are less exposed to wind, which can lead to later growth onset.   We conclude that daily LiDAR time-series enables measurements that are challenging to achieve using other techniques, such as detecting the onset of height growth. Our study suggests that the onset of height growth may be mainly influenced by light competition and microclimate, demonstrating the potential of tree-level LiDAR-derived metrics in studying how microclimatic changes affect forest adaptability in the context of a changing climate.  We will further continue to study the influence of the timing of growth on the amount of growth during the growing season.