This study evaluated the temporal variation and inter-population differences in needle moisture content of Scots pine (Pinus sylvestris L.) seedlings grown from five natural populations representing different altitudinal zones. The populations ranged from sea level to 2250 meters in elevation, and the seedlings were cultivated under uniform nursery conditions at the Faculty of Forestry, Karadeniz Technical University, for four years. Needle samples were collected monthly over a 23-month period from a total of 750 seedlings, and fresh and dry weights were recorded to calculate needle moisture content. Two-way analysis of variance (ANOVA) revealed that both population and sampling time had statistically significant effects (p < 0.05), whereas their interaction was not significant. The lowest mean needle moisture content was observed in the Çamburnu population (0–450 m), while the highest was recorded in Zigana-3 (1800–2250 m), suggesting that high-elevation populations may have developed more effective water retention strategies. Seasonally, higher moisture levels were recorded in winter and early spring, while a decline was observed during summer months due to increased temperatures. The relationship between needle moisture and weight parameters varied among populations. These findings indicate that needle moisture content is a physiologically sensitive parameter influenced by both environmental conditions and elevation-driven genetic variation. The results highlight the importance of prioritizing high-elevation populations in future afforestation efforts aimed at enhancing drought tolerance and climate change adaptation.

ABSTRACTScots pine (Pinus sylvestris L.) is characterized by considerable intraspecific adaptive variability in response to environmental stress factors due to its wide geographical range. Adaptability is key for forestry, promising resilience against upcoming Europe's climate‐driven droughts. We studied three provenances of pedigreed Scots pine seedlings from distinct upland and lowland habitats in the Czech Republic. A water deficit was induced in 2‐year‐old, potted seedlings in a greenhouse. Their physiological responses to drought were investigated at the beginning of growing season during the development of new shoots, and after subsequent summer rewatering. (1) We analyzed several physiological traits to assess their effectiveness in detecting treatment effects: steady‐state quantum yield of PSII (QY Lss), maximum quantum yield of PSII (QY max), steady‐state non‐photochemical quenching (NPQ Lss), needle chlorophyll fluorescence ratio (SFR_R), and needle temperature normalized to ambient temperature (∆T), using a high‐throughput phenotyping unit. The divergence in SFR_R, QY max, QY Lss, NPQ Lss, and ΔT suggests that drought stress significantly impacts photosynthetic efficiency and heat dissipation, with recovery occurring after rewatering. (2) We detected differences within and among provenances utilizing a single nucleotide polymorphism genotyping array and linear mixed models integrating estimated genomic relationships to investigate genetic variation in needle functional traits in time. Throughout the experiment, heritability (h2 ) varied widely among traits—with QY max and QY Lss showing the greatest variability (from 0 to 0.37), NPQ Lss exhibiting a narrower range aside from two outlier peaks, and SFR_R and ∆T displaying lower variability and lower h2 values (0–0.24). The photosynthesis‐related traits (QY max, QY Lss) showed the highest genetic variation, underscoring their potential for early‐age phenotyping and selection of drought‐tolerant genotypes. These findings address practical problems in forest management, particularly in light of changing weather patterns and climate variability, and provide a foundation for advanced optically based, early‐age phenotyping to enhance forest resilience.

Chronic Exposure to Ionizing Radiation Elicits Growth Inhibition and a Dynamic Oxidative Stress Response in the Shoots of Scots Pine (Pinus sylvestris) Seedlings

Natural regeneration and development of Scots pine seedlings in continuous cover forestry in northern Finland

The industrial production of conifer seedlings in nurseries uses large amounts of fertilizers to ensure their proper growth and accurate nutrient status. However, inorganic nitrogen fertilization leads to nitrate leaching, which has negative environmental consequences. An alternative solution could be the use of controlled-release fertilizers that supply nutrients over longer periods and hence have a lower environmental impact. This study analysed the performance of a novel arginine-iron-hexametaphosphate complex on Scots pine (Pinus sylvestris) seedlings. The complex was characterized using a wide range of analytical tools, indicating that it is a precipitated complex rather than a crystalline compound. Plant growth on arginine-iron-hexametaphosphate was comparable to a commercial inorganic nitrogen controlled-release fertilizer but with significantly lower nitrate leaching. A nitrogen budget of seedlings and growth substrate showed that seedlings had acquired nitrogen in excess of the amount of nitrogen present at the start of the experiment, and this excess nitrogen was smaller in seedlings grown on the inorganic fertilizer. Measurements of acetylene reduction in seedlings indicated low but measurable rates of nitrogen fixation, potentially contributing to the excess nitrogen. Together, the results showed that the arginine-iron-hexametaphosphate complex is a good alternative to commonly used fertilizers and can contribute to sustainable seedling production.

Abstract In Sweden, browsing by large herbivores hampers seedling establishment and causes substantial growth losses in economically important, regenerating Scots pine (Pinus sylvestris) stands. In addition, suboptimal site conditions often require mechanical site preparation (MSP) to promote seedling establishment by improving substrate quality and reducing vegetation competition and pest damage. Here, we examined the interaction between herbivore exclusion fencing and regeneration method (natural, seed-sown) on sapling height and radial growth, as well as the interplay between exclusion fencing and MSP (harrowing, mounding) on the growth of planted seedlings. There was no significant interaction between regeneration method and fencing for either of the two growth variables (height, radial growth). Both regeneration techniques resulted in similar growth performance regardless of fencing. Fencing caused greater height (+17%) and radial growth (+7%), irrespective of regeneration method. A significant interaction between MSP and fencing was observed for both height and radial growth. Without fence, height and radial growth were similar in both MSP methods. With fencing, harrowing stimulated seedling height growth by 25% and radial growth by 48% compared to mounding, which exhibited similar growth patterns as mounding without a fence. Our findings highlight the interplay between MSP and herbivore exclusion and indicate that harrowing is far superior to mounding when fencing is technically and economically feasible. This study provides actionable guidance for forest managers aiming to promote Scots pine more prominently in the future.

The damage to the stems of pine seedlings during manual care in crops, the density of crops and the yield of standard planting material, as well as the basic density of wood of the stems of 2-year-old Scots pine seedlings in nurseries of the forest and forest-steppe zones of the Trans-Urals have been studied. In field conditions, seedlings have been sorted according to the nature of the damage to the stems. In the laboratory, the biometric parameters of seedlings have been measured and the basic density of the wood of the stems in the 1st and 2nd years of growth using the maximum moisture method. It has been established that the planting material of Scots pine in nurseries of forest and forest-steppe zones of the Trans-Urals is divided into 3 main categories: without signs of mechanical damage, with signs of mechanical damage and with bifurcation of the stem, arising as a result of spontaneous or induced mutations. The proportion of seedlings with mechanical damage in forest zone nurseries is small – no more than 11 %. In nurseries of the forest-steppe zone such seedlings account for 30 %. It has been shown that in forest zone nurseries, in some cases, the density of crops is increased. The yield of standard 2-year-old seedlings varies significantly across nurseries in both the forest and forest-steppe zones and does not have a clearly defined relationship with the density of the stand. It has been noted that 2-year-old pine seedlings grown in forest zone nurseries are characterized by significantly lower biometric parameters of the stems. It has been established that in the 1st year of cultivation, pine seedlings in the forest and forest-steppe zones practically do not differ in height growth rates. In the 2nd year, pine seedlings in the forest-steppe zone generally have significantly higher growth rates in height than seedlings in the forest zone. In pine seedlings in the forest zone, the basic density of the wood of the stems is significantly higher compared to seedlings in the forest-steppe zone. The ratio of this indicator for shoots of the 2nd and 1st years of cultivation for nurseries in the forest zone has averaged 0.80, and for the forest-steppe – 0.85.

Abstract Forests destroyed during the current Russian invasion in Ukraine require urgent restoration and renewal. Considering that the forests are still inaccessible due to the ongoing occupation, it is important to conduct computer simulations of their possible artificial renewal. For this purpose, Urban Forest Biomass (UFB) computer model was parameterized by means of the data from 60 sample plots (SPs) established in the Scots pine (Pinus sylvestris L.) stands growing in the Luhansk region in Ukraine and validated for two representative plots. The forests growing on two SPs selected for model validation were established in 2014. UFB model validation was made based on the data collected in 2021, and the prediction was made for 2030. The modeled tree height was highly correlated with values observed in the field in 2021 (R 2 = 0.9579, root mean square error [RMSE] = 0.0264, systematic error [BIAS] = 0.0013 for SP 1 and R 2 = 0.9601, RMSE = 0.0305, BIAS = 0.0164 for SP 2). The forecast of future forest development was conducted for high (SP 1) and low (SP 2) initial tree density. The simulation results for the current climatic conditions showed that in SP 1, up to 33.44% of planted Scots pine could die until 2030. In SP 2, the percentage of dead trees was lower (22%). In the warm-dry scenario, the simulations showed an increase in the percentage of Scots pine mortality up to 78% for SP 1 and 29.76% for SP 2. The predictions confirmed the hypothesis about the negative impact of high density on the development of planted trees and their increased mortality in the warm-dry scenario. The high autocorrelation of the analyzed number of Scots pine trees suggests their high growth potential in the research area. On the basis of the results obtained, we recommend planting of a relatively small number of Scots pine seedlings (3,333 individuals/ha) to ensure their greater survival in steppe conditions of East Ukraine under the influence of warfare and warm-dry climate change scenario.

For establishment and growth of newly planted seedlings it is essential to overcome environmental stress at the planting site. Adding the amino acid arginine at planting is a novel treatment aiming at increased establishment success, so far tested in a limited number of applied studies. We examined the effects of adding arginine-phosphate (arGrow®), mechanical site preparation (MSP), and planting time on survival and growth of Norway spruce and Scots pine seedlings in two field experiments in boreal southeastern Norway. After three growing seasons, survival for spring planted seedlings of both species was significantly better following MSP, while addition of arginine-phosphate did not have any effect. Autumn planted pine seedlings with MSP and arginine had higher survival and also larger diameter than spring planted ones with MSP but without arginine. Spruce and pine seedlings with MSP were taller and had larger diameter than those without MSP. For spring planted seedlings of both species, dry weight of roots and shoots was positively affected by MSP, but not by arginine. To conclude, arginine-phosphate had neutral to modestly positive effects on survival and growth, while MSP had clear positive effects. The effect of planting time varied with species.

ABSTRACT Understanding the interactions between mycorrhizal fungi and trees in drought conditions is increasingly important for forest sustainability. We conducted a water manipulation experiment with Quercus robur (oak) and Pinus sylvestris (pine) seedlings, both inoculated with the ectomycorrhizal fungus Hebeloma crustuliniforme. Over three years, we examined how varying water regimes (sublethal drought, water deficit, optimal supply) impacted the above – and belowground growth and allometry of mycorrhized and non-mycorrhized seedlings to assess the effects of mycorrhization under different water availability conditions. Responses to water regimes were species-specific and influenced by mycorrhization. Pine exhibited significant effects on aboveground parameters, particularly diameter, while belowground traits and allometry under drought showed smaller differences between mycorrhized and non-mycorrhized seedlings. Drought stress in mycorrhized pine resulted in a less favorable, lower root-to-leaf ratio. In contrast, oak responded to mycorrhization with greater height, total biomass, and root architecture, compared to non-mycorrhized seedlings, especially under optimal conditions. Our findings suggest that the growth mechanisms in young oak may enhance rooting, potentially leading to improved efficiency in mycorrhizal utilization. However, drought negatively affected seedlings of both species and their symbiont, highlighting the limited effectiveness of artificial mycorrhization in mitigating the challenges posed by climate change.

An experimental study was carried out on the use of dry residual components from the processing of algae (laminaria palmate, Laminaria digitata, kelp saccharine, Saccharina latissima and two varieties of fucus: fucus vesicularis, Saccharina latissima and ascophyllum nodosum, Ascophyllum nodosum). “Veltorf” substrate, prepared on the basis of high-moor peat, was used as the basis for the substrate compositions. Using generally accepted methods, a complex of water-physical and agrochemical indicators was studied. Based on the results of the experiment, it was established that the addition of dry residual components from algae processing does not significantly affect the water-physical properties of the experimental substrates. At the same time, a noticeable alkalization of the substrate is shown when even 10 % of algae components is added and the pH of the environment increases. Algal dry components, when applied in small doses, can slightly increase the mobile potassium in the soil solution of the substrate; with an increase in the application dose, more than 50% maintains the level of potassium corresponding to the base substrate. The addition of dry algal components in an amount of 30% or more leads to a decrease the nitrate nitrogen and mobile phosphorus in the substrate. In the process of annual Scots pine seedlings growing in a greenhouse on substrates with algae, greater losses of mobile potassium and nitrate nitrogen occur than in the control, despite of mineral fertilizers adding according to technology, as well as alkalization of the substrates. There is a noticeable release of phosphates, directly related to the proportion of the algal component introduced. Such an imbalance in plant nutrition and environmental reaction led to growth degradation of seedlings in the first year of life. The positive effect only the growth of the main root of the seedlings. The use of algae residual processing as an additive to ready-made substrates is possible only in small doses (no more than 20%), but one can expect greater positive results when using acidic natural peats as a base for preparing substrates.

This study aims to evaluate the afforestation success based on the 10-year development of Scots pine (Pinus sylvestris L.) seedlings planted at higher elevations within the current forest boundary as part of the "Galyan Afforestation Project." Sample plots were selected from the Scots pine reforestation area, established in 2007, based on three different aspects (north, northeast, northwest) and two elevation ranges (1790–1890 m, 1891–1990 m). In 2011, data were collected from each sample plot, including seedling length, root collar diameter, the number of branches on the latest shoot, the lengths of the longest branches in the north, south, east, and west directions, and the number of terminal buds. Additionally, the growth trends of the same areas were monitored based on on-site inspections conducted in 2016 (when the seedlings were 10 years old), and evaluations were made accordingly. Statistical tools such as ANOVA, Duncan test, t-test, and correlation analysis were employed to evaluate growth performance. The results showed that the average seedling height was 59.64 cm in 2010 and 93.85 cm in 2016, with height growth being more pronounced at lower elevations and on north-facing slopes. While initial growth was adequate, extreme climatic conditions such as frost, snow pressure, and waterlogging led to deformities, including branch and terminal shoot damage. Despite these challenges, the findings highlight that careful site selection—favoring northern aspects and lower elevations—can enhance growth outcomes. Furthermore, integrating ecological and forestry research with practical forestry strategies is essential for sustainable reforestation in mountainous regions.

The results of a two-year experiment on Scots pine (Pinus sylvestris L.) seedlings growing in a forest nursery are presented. Pine seeds were pre-treated with extractives (neutral and acidic components) isolated by emulsion method from spruce green left after timber harvesting. Phenolic acids dominated in acidic components. Essential oils, polyprenols, carotenoids and other biologically active substances are among the neutral components of spruce greenery. We assessed biometric parameters and structural features of seedlings. The intensity of mycorrhization of roots was determined in 1-year-old seedlings, and the elemental composition of needles and the wood density of stems were studied in 2-year-old seedlings. The analysis of pine needles revealed a higher potassium content in the K-Ca pair when acidic components of the biopreparation were applied. This indicates more active photosynthetic processes and transport of assimilates to the plant organs, providing active growth of seedlings in this variant. Acidic components at a dose of 0.5 g/kg of seeds stimulate the growth of seedlings when the process of cell hardening and lignification of increment lags. Neutral components have a positive effect on the formation of the main morphometric characteristics and physical properties of wood. At a dose of 0.012 g/kg of seeds, they increase seedlings preservation in adverse weather conditions. Based on the totality of the studied characteristics, a more in-depth study of neutral components effect is necessary, since neutral components of spruce greenery had a positive effect on seedlings preservation and contributed to both the activation of growth processes and the formation of optimal physical parameters of plants.

The purpose of the research is to investigate the resistance of Pinus sylvestris, P. sibirica and Larix sibirica pine seedlings to the nematode Bursaphelenchus xylophilus to assess the potential risk of death of these conifers from pine wilt disease.Materials and methods. In the experiment, 8-year-old seedlings of P. sylvestris, P. sibirica and 4–5-year-old seedlings of L. sibirica were used in an amount of 16 seedlings of each species (8 B. xylophilus-infected plants and 8 control plants).Results and discussion. Pines Pinus sylvestris, P. sibirica and L. sibirica were susceptible to the pine wood nematode B. xylophilus. All plants died by the end of the study, but the most rapid wilting and death of plants was observed in Siberian larch seedlings. More intensive nematode reproduction was recorded in P. sibirica, with seedlings dying later than other plants. The preliminary analysis showed that the death of conifer stands of the studied species from pine wilt disease is possible in the climatic zone of Siberia.

BackgroundMutualistic mycorrhiza fungi that live in symbiosis with plants facilitates nutrient and water acquisition, improving tree growth and performance. In this study, we evaluated the potential of mutualistic fungal inoculation to improve the growth and disease resistance of Scots pine (Pinus sylvestris L.) against the forest pathogen Heterobasidion annosum.ResultsIn co-inoculation experiment, Scots pine seedlings were pre-inoculated with mutualistic beneficial fungus (Suillus luteus) prior to H. annosum infection. The result revealed that inoculation with beneficial fungus promoted plant root growth. Transcriptome analyses revealed that co-inoculated plants and plants inoculated with beneficial fungus shared some similarities in defense gene responses. However, pathogen infection alone had unique sets of genes encoding pathogenesis-related (PR) proteins, phenylpropanoid pathway/lignin biosynthesis, flavonoid biosynthesis, chalcone/stilbene biosynthesis, ethylene signaling pathway, JA signaling pathway, cell remodeling and growth, transporters, and fungal recognition. On the other hand, beneficial fungus inoculation repressed the expression of PR proteins, and other defense-related genes such as laccases, chalcone/stilbene synthases, terpene synthases, cytochrome P450s. The co-inoculated plants did not equally enhance the induction of PR genes, chalcone/stilbene biosynthesis, however genes related to cell wall growth, water and nutrient transporters, phenylpropanoid/lignin biosynthesis/flavonoid biosynthesis, and hormone signaling were induced.ConclusionS. luteus promoted mutualistic interaction by suppressing plant defense responses. Pre-inoculation of Scots pine seedlings with beneficial fungus S. luteus prior to pathogen challenge promoted primary root growth, as well as had a balancing buffering role in plant defense responses and cell growth at transcriptome level.

The treatment of quarry wastewater, as well as the reclamation of depleted coal mines, are serious environmental problems. One of the ways to solve them is phytoremediation using stress-resilient plants such as the common pine (Pinus sylvestris L.). To mitigate the risk of epiphytotics during mass cultivation, treatments with chemical pesticides are necessary. It is important to make sure that the pesticides do not harm plants when using quarry wastewater containing heavy metals for irrigation. In this regard, mass monitoring of plants by non-invasive methods is highly relevant. In this work, we used direct measurement methods and a non-invasive approach based on hyperspectral imaging to comprehensively monitor the condition of pine seedlings treated with the “Aktara” and “Previcur Energy” pesticides in different concentrations (single, double, and quadruple compared to the concentration recommended by the manufacturer) and irrigated with the solutions of mineral salts simulating the wastewater from coal mines. It is shown that, despite some methodological difficulties, it is possible to use hyperspectral images for non-invasive remote monitoring of the condition of coniferous seedlings in vegetation experiments, including in the field. It was found that the pesticide treatments exerted neither acute toxicity nor a pronounced negative effect on the growth rate and pigment composition of the pine seedlings during the two-month observation. At the same time, irrigation of these plants with model quarry wastewater also did not produce synergistic toxic effects. Thus, there are no obvious obstacles to the use of the above-mentioned pesticides for treatment of Scots pine seedlings irrigated with quarry wastewater containing Fe, Zn and Mn. The results obtained also support the use of wastewater rich in mineral nutrition elements but lacking highly toxic heavy metals (such as Pb and Cd), when growing plants for phytoremediation of soils from depleted coal mines. However, long-term, preferably multi-year studies are needed to assess long-term risks.

An attempt was made to analyze the possibility of creating carbon farms on worked out clay quarries in the Middle Ural taiga forest region. The research is based on the method of trial plots which ensures the receipt of objective data on productivity of artificial plantations created on lands disturbed by clay extraction process. It has been established that in the specifi ed forestry regions the forestry direction of reclamation ensures the formation of relatively productive pine plantations. The latter, in the process of Photosynthesis extract carbon dioxide from the atmospheric air, depositing carbon in their tissues, thereby reducing the share of greenhouse gases and slowing down climate change. By the age of 50, up to 120 t/ha of carbon is deposited in stem wood alone. Carbon in wood is stored not only for the period of its cultivation, but also for the period of use of its processed products (furniture, boards, wooden structures, etc.), that is, for an indefi nite period. Therefore, it can be stated that the creation of carbon farms on depleted clay quarries by planting 2-year-old seedlings of Scots pine solves not only the problem of providing the industry with wood and improving the environmental situation, but also implements a project to slow down climate change.

Super-absorbents are expected to amend soils as they are capable of retaining water, which turns dry loose powdery substances (also capsule) into hydrogel. These were applied to prevent an artificial regeneration failure due to drought events. Four commercially-available products were mixed with soil from planting holes (the capsule was put to the soil) in order to support bare-root Scots pine and European beech seedlings after a spring planting on eleven clear-cut sites in 2020–2021. The plantations were designed as rows with 4 × 150 plants treated with four hydrogels plus 150 plants without hydrogel as a control. The performance evaluation of new plantations was based on attributes such as mortality/survival and relative height and root-collar diameter increments. The plants, which lost their initial size, due to pine weevil damage, dry tops and damage by game, were excluded from the evaluation. Besides the plant response to the applied super-absorbents, the planting operations were evaluated from economic point of view. The 2020 plantations showed higher mortality than 2021 ones; both years showed an excessive loss. The hydrogels did not help the plants to survive better compared to control and growth data also showed ambiguous results. Therefore, from commercial perspective, the application of all tested super-absorbents just increased the renewal costs.

We studied responses of needle terpene concentrations and resin canal characteristics to warming in Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) seedlings grown in a controlled field set-up in eastern Finland. Warming was simulated during the growing seasons using infrared heaters that increased air temperature in study 1 (2016–2019) by 1°C and in study 2 (2019–2020) by 2°C and 4°C, compared to ambient conditions. Terpenes were sampled in study 1 from non-matured current year and matured previous year needles in June 2019, and study 2 from mature current-year needles in August 2020. In study 1, we also studied resin canal anatomy. We found that 1°C elevation of temperature caused two-fold increase in concentrations of total terpenes, oxygenated monoterpenes and sesquiterpenes of non-matured current year needles of Norway spruce. Further, it caused 1.3-1.8-fold increases in sesquiterpene concentrations both in unmatured and matured needles of Scots pine. It also decreased resin canal diameter of mature needles in Norway spruce. In study 2, the stronger warming treatments did not affect terpene concentrations of matured current-year needles in either species. Based on our findings, even minor elevation of temperature may affect terpene concentrations of non-mature needles in boreal conifers.

Biogenic secondary organic aerosols (SOAs) can be formed from the oxidation of plant volatiles in the atmosphere. Herbivore-induced plant volatiles (HIPVs) can elicit plant defenses, but whether such ecological functions persist after they form SOAs was previously unknown. Here we show that Scots pine seedlings damaged by large pine weevils feeding on their roots release HIPVs that trigger defenses in neighboring conspecific plants. The biological activity persisted after HIPVs had been oxidized to form SOAs, which was indicated by receivers displaying enhanced photosynthesis, primed volatile defenses, and reduced weevil damage. The elemental composition and quantity of SOAs likely determines their biological functions. This work demonstrates that plant-derived SOAs can mediate interactions between plants, highlighting their ecological significance in ecosystems.