Explore the vast range of titles available.

Background Understanding how ecotypic divergence persists under extensive gene flow is critical for predicting adaptive responses in long-lived conifers. Mongolian Scots pine ( Pinus sylvestris var. mongolica ) occupies contrasting mountain and sandy-dune habitats in northeastern China, forming two ecotypes with distinct environmental adaptations. Using reference-free Specific Locus Amplified Fragment sequencing (SLAF-seq) data and genome-wide SNPs, we explored patterns of genomic differentiation and genotype-environment associations to determine whether adaptive divergence is driven by few large-effect loci or polygenic shifts. Results Despite weak population structure, we identified ~ 3% of the genome as adaptive outliers with strong differentiation between ecotypes. These loci exhibited significant environmental associations indicating that both adaptive genomic islands and polygenic shifts are dominated by large-effect variants rather than minor-effect alleles. Furthermore, phenotypic differentiation between ecotypes reflected a dual mechanism: adaptive genetic divergence shaping hydraulic traits and mechanical support, and genotype-by-environment (G×E) interactions enabling phenotypic plasticity in physiological responses, such as water-use efficiency and stress tolerance. Conclusion The interplay between hard genetic adaptation and plasticity highlights how Mongolian Scots pine can simultaneously preserve ecotypic differentiation and respond flexibly to environmental heterogeneity. Importantly, such plasticity may provide a critical buffer against rapid climate change, allowing populations to persist despite ongoing gene flow and delayed genomic divergence. Our study highlights how divergent selection and plasticity together maintain ecotypic divergence in wind-pollinated pine variety with high gene flow and demonstrates a novel reference-free approach for dissecting adaptive architectures in non-model genomes.

Many studies have addressed several plant-insect interaction topics at nutritional, molecular, physiological, and evolutionary levels. However, it is still unknown how flexible the metabolism and the nutritional content of specialist insect herbivores feeding on different closely related plants can be. We performed elemental, stoichiometric, and metabolomics analyses on leaves of two coexisting Pinus sylvestris subspecies and on their main insect herbivore; the caterpillar of the processionary moth (Thaumetopoea pityocampa). Caterpillars feeding on different pine subspecies had distinct overall metabolome structure, accounting for over 10% of the total variability. Although plants and insects have very divergent metabolomes, caterpillars showed certain resemblance to their plant-host metabolome. In addition, few plant-related secondary metabolites were found accumulated in caterpillar tissues which could potentially be used for self-defense. Caterpillars feeding on N and P richer needles had lower N and P tissue concentration and higher C:N and C:P ratios, suggesting that nutrient transfer is not necessarily linear through trophic levels and other plant-metabolic factors could be interfering. This exploratory study showed that little chemical differences between plant food sources can impact the overall metabolome of specialist insect herbivores. Significant nutritional shifts in herbivore tissues could lead to larger changes of the trophic web structure.

Small air pressure fluctuations in the atmosphere are responsible for the pressure pumping effect, which leads to an enhancement of soil gas transport. To investigate the spatial variability of these air pressure fluctuations, several high-precision differential pressure sensors were installed at the floor of a Scots pine forest. The alignment of the pressure sensors allowed for the determination of the propagation direction and speed of the observed air pressure fluctuations. Below-canopy and above-canopy airflow characteristics were monitored to find possible links between the air pressure fluctuations and the airflow. Results show that the propagation direction of the air pressure fluctuations observed at the forest floor correspond to the above-canopy and not to the below-canopy wind direction. Moreover, propagation speed of the air pressure fluctuations is higher than the below-canopy wind speed and corresponds to above-canopy wind speed. These findings indicate a connection between below-canopy air pressure fluctuations and above-canopy airflow. The air pressure fluctuations were found to be well correlated up to a distance of 15 m. With increasing distance, the correlation strongly decreases. However, the calculated pressure pumping coefficient, which quantifies the strength of the pressure pumping effect, yields similar values up to a distance of 90 m. This allowed specifying the range of influence of the air pressure fluctuations.

Phenolics and extracted phenolic compounds of Scots pine ( Pinus sylvestris ) and Norway spruce ( Picea abies ) show antibacterial activity against several bacteria. The majority of phenolic compounds are stilbenes, flavonoids, proanthocyanidins, phenolic acids, and lignans that are biosynthesized in the wood through the phenylpropanoid pathway. In Scots pine ( P. sylvestris ), the most abundant phenolic and antibacterial compounds are pinosylvin-type stilbenes and flavonol- and dihydroflavonol-type flavonoids, such as kaempferol, quercetin, and taxifolin and their derivatives. In Norway spruce ( P. abies ) on the other hand, the main stilbene is resveratrol and the major flavonoids are quercetin and myricetin. In general, when the results from the literature regarding the activities of flavonoid glycosides and their aglycones against a total of twenty-one microorganisms are summarized, it was found that phenolic glycosides are less active than the corresponding aglycones, although a number of exceptions are also known. The aglycones in plants respond to various kinds of biotic stress. Synergistic effects between aglycones and their glycosides have been observed. Minimum inhibition concentrations of below 10 mg L −1 against bacteria have been reported for gallic acid, apigenin, and several methylated and acylated flavonols present in these industrially important trees. In general, the phenolic compounds are more active against Gram-positive bacteria, but apigenin is reported to exhibit strong activity against Gram-negative bacteria. The present review lists some of the biosynthesis pathways for the antibacterial phenolic metabolites found in Scots pine ( P. sylvestris ) and Norway spruce ( P. abies ). The antimicrobial activity of the compounds is collected and compared to gather information about the most effective secondary metabolites.

The growth of a tree depends on the size, shape, and functioning of the crown. The length of the crown is a somewhat subjective value because the base of the crown is often difficult to determine. The aim of this study was to develop an allometric model to calculate the crown length of Pinus sylvestris L., which might serve as an alternative to the current equations used especially for stands of variable density. The model used three predictive variables, i.e., diameter at breast height, tree height, and density. The developed crown length model showed high compatibility with empirical data within the studied stands differing in diameter at breast height, height, age, biosocial position, and, above all, density (SD = 1.786). The correlation coefficient between the empirical crown length for the stand (H[sub.emp] [sup.*] ) and the calculated model (H[sub.cal] [sup.*] ) was r = 0.974, with a discrepancy of (±) 3.17%. The derived crown length model can be one of the components used to estimate the mass of needles or leaf area index (LAI) and, consequently, the amount of transpiration or the amount of carbon dioxide bound, which is crucial in the context of climate change.

The Spearman rank correlation coefficient is a non-parametric (distribution-free) rank statistic proposed by Charles Spearman as a measure of the strength of the relationship between two variables. It is a measure of a monotonic relationship that is used when the distribution of the data makes Pearson’s correlation coefficient undesirable or misleading. The Spearman coefficient is not a measure of the linear relationship between two variables. It assesses how well an arbitrary monotonic function can describe the relationship between two variables, without making any assumptions about the frequency distribution of the variables. Unlike Pearson’s product-moment (linear) correlation coefficient, it does not require the assumption that the relationship between variables is linear, nor does it require that the variables be measured on interval scales; it can be applied to variables measured at the ordinal level. The purpose of this study is to compare the values of Pearson’s product-moment correlation coefficient and Spearman’s rank correlation coefficient and their statistical significance for six morpho-anatomical traits of L. (original – for Pearson’s coefficient, and ranked – for Spearman’s coefficient) estimated from all observations, object means (for trees), and medians. The results show that the linear and rank correlation coefficients are consistent (as to direction and strength). In cases of divergence in the direction of correlation, the correlation coefficients were not statistically significant, which does not imply consistency in decision-making. Estimation of correlation coefficients based on medians is robust to outlier observations and factors that linear correlation is then very similar to rank correlation.

The article presents the results of thermo-mechanical densification tests conducted on Scots pine timber. The densification process was carried out in industrial conditions with a high-pressure press, which allowed flat compression of boards that were up to 2.5 m long. A phenomenon of elastic redeformations was observed in the densified boards after each pulse of compression. As a result of thermo-mechanical compression, the average timber moisture content dropped to 9%, and the average density increased by 13.5%, from the level of 547 to 621 kg/m[sup.3] . As a result of thermo-mechanical densification, the strength class C of most Scots pine timber pieces improved. Most timber pieces that were subjected to thermo-mechanical densification have improved their strength class, C, by one (72.7% of the tested batch) or two C classes (3.6% of the batch under study).

• Heatwaves combined with drought affect tree functioning with as yet undetermined legacy effects on carbon (C) and nitrogen (N) allocation. • We continuously monitored shoot and root gas exchange, δ13CO₂ of respiration and stem growth in well-watered and drought-treated Pinus sylvestris (Scots pine) seedlings exposed to increasing daytime temperatures (max. 42°C) and evaporative demand. Following stress release, we used 13CO₂ canopy pulse-labeling, supplemented by soil-applied 15N, to determine allocation to plant compartments, respiration and soil microbial biomass (SMB) over 2.5 wk. • Previously heat-treated seedlings rapidly translocated 13C along the long-distance transport path, to root respiration (R root; 7.1 h) and SMB (3 d). Furthermore, 13C accumulated in branch cellulose, suggesting secondary growth enhancement. However, in recovering drought-heat seedlings, the mean residence time of 13C in needles increased, whereas C translocation to R root was delayed (13.8 h) and 13C incorporated into starch rather than cellulose. Concurrently, we observed stress-induced low N uptake and aboveground allocation. • C and N allocation during early recovery were affected by stress type and impact. Although C uptake increased quickly in both treatments, drought-heat in combination reduced the above–belowground coupling and starch accumulated in leaves at the expense of growth. Accordingly, C allocation during recovery depends on phloem translocation capacity.

Climate change exposes ecosystems to strong and rapid changes in their environmental boundary conditions mainly due to the altered temperature and precipitation patterns. It is still poorly understood how fast interlinked ecosystem processes respond to altered environmental conditions, if these responses occur gradually or suddenly when thresholds are exceeded, and if the patterns of the responses will reach a stable state. We conducted an irrigation experiment in the Pfynwald, Switzerland from 2003–2018. A naturally dry Scots pine (Pinus sylvestris L.) forest was irrigated with amounts that doubled natural precipitation, thus releasing the forest stand from water limitation. The aim of this study was to provide a quantitative understanding on how different traits and functions of individual trees and the whole ecosystem responded to increased water availability, and how the patterns and magnitudes of these responses developed over time. We found that the response magnitude, the temporal trajectory of responses, and the length of initial lag period prior to significant response largely varied across traits. We detected rapid and stronger responses from aboveground tree traits (e.g., tree-ring width, needle length, and crown transparency) compared to belowground tree traits (e.g., fine-root biomass). The altered aboveground traits during the initial years of irrigation increased the water demand and trees adjusted by increasing root biomass during the later years of irrigation, resulting in an increased survival rate of Scots pine trees in irrigated plots. The irrigation also stimulated ecosystem-level foliar decomposition rate, fungal fruit body biomass, and regeneration abundances of broadleaved tree species. However, irrigation did not promote the regeneration of Scots pine trees, which are reported to be vulnerable to extreme droughts. Our results provide extensive evidence that treeand ecosystem-level responses were pervasive across a number of traits on long-term temporal scales. However, after reaching a peak, the magnitude of these responses either decreased or reached a new stable state, providing important insights into how resource alterations could change the system functioning and its boundary conditions.

Abstract The soil microbiome is crucial for regulating biogeochemical processes and can, thus, strongly influence tree health, especially under stress conditions. However, little is known about the effect of prolonged water deficit on soil microbial communities during the development of saplings. We assessed the response of prokaryotic and fungal communities to different levels of experimental water limitation in mesocosms with Scots pine saplings. We combined analyses of physicochemical soil properties and tree growth with DNA metabarcoding of soil microbial communities throughout four seasons. Seasonal changes in soil temperature and soil water content and a decreasing soil pH strongly influenced the composition of microbial communities but not their total abundance. Contrasting levels of soil water contents gradually altered the soil microbial community structure over the four seasons. Results indicated that prokaryotic communities were less resistant to water limitation than fungal communities. Water limitation promoted the proliferation of desiccation tolerant, oligotrophic taxa. Moreover, water limitation and an associated increase in soil C/N ratio induced a shift in the potential lifestyle of taxa from symbiotic to saprotrophic. Overall, water limitation appeared to alter soil microbial communities involved in nutrient cycling, pointing to potential consequences for forest health affected by prolonged episodes of drought. Despite the influence of the sampling time point, water limitation altered soil microbial community structures in Scots pine mesocosms, but fungal taxa were less sensitive to reduced soil water contents.