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• Background and Aims Our knowledge about the influences of environmental factors on tree growth is principally based on the study of dominant trees. However, tree social status may influence intra-annual dynamics of growth, leading to differential responses to environmental conditions. The aim was to determine whether withinstand differences in stem diameters of trees belonging to different crown classes resulted from variations in the length of the growing period or in the rate of cell production. • Methods Cambial activity was monitored weekly in 2006 for three crown classes in a 40-year-old silver-fir (Abies alba) plantation near Nancy (France). Timings, duration and rate of tracheid production were assessed from anatomical observations of the developing xylem. • Key Results Cambial activity started earlier, stopped later and lasted longer in dominant trees than in intermediate and suppressed ones. The onset of cambial activity was estimated to have taken 3 weeks to spread to 90 % of the trees in the stand, while the cessation needed 6 weeks. Cambial activity was more intense in dominant trees than in intermediate and suppressed ones. It was estimated that about 75 % of tree-ring width variability was attributable to the rate of cell production and only 25 % to its duration. Moreover, growth duration was correlated to tree height, while growth rate was better correlated to crown area. • Conclusions These results show that, in a closed conifer forest, stem diameter variations resulted principally from differences in the rate of xylem cell production rather than in its duration. Tree size interacts with environmental factors to control the timings, duration and rate of cambial activity through functional processes involving source-sink relationships principally, but also hormonal controls.

Abies alba Mill. (silver fir) needs specific soil and humidity conditions and seedlings are vulnerable to climatic extremes. Surprisingly, successful seedling establishment has been observed in disturbed habitats like active quarries. We compared 2-year old fir seedlings in three habitats—natural fir forest, disturbed forest, and exposed quarry—to explore the biochemical features that help them endure the first stages of succession in harsh environments. We assessed a range of parameters including reactive oxygen species (ROS) levels, antioxidant activity (2,2-diphenyl-1-picrylhydrazyl reduction), foliar pigments (chlorophylls and carotenoids), C and N contents, nonstructural carbohydrates, phenolics, and cell wall components analyzed via Fourier Transform Infrared (FTIR) spectroscopy, as well as ectomycorrhizal colonization and diversity. The analysis indicated that the fir seedlings were in unexpectedly good physiological condition despite the environmental constraints. Continuous exposure to harsh conditions (stony soils poor in C and N, extreme insolation, potential drought/flooding stress, etc.) was only slightly associated with ROS and antioxidant levels, roots of seedlings were fully mycorrhized, and their roots did not express signals of severe oxidative stress. Only a few seedling features clearly followed the environmental gradient; C (%), ectomycorrhizal fungal richness in roots, and total antioxidant content in stems decreased in harsh environments. Despite the lower chlorophyll levels, seedlings from the quarry had no decrease in C or N foliar levels. These firs did not have impaired N- or C-compound levels. Quarry seedlings had the highest nonstructural carbohydrates in needles and roots, protective foliar shifts (more carotenoids), and stronger stems (more structural carbohydrates, especially lignin). These findings demonstrate strong acclimatization capacity of A. alba seedlings and suggest the existence of stabilizing physiological mechanisms supporting survival in disturbed environments.

In recent years, phytofunctionalized AgNPs have attracted great interest due to their remarkable biological activities. In the present study, AgNPs were synthesized using Abies alba and Pinus sylvestris bark extracts. The chemical profile of these bark extracts was analyzed by LC-HRMS/MS. As a first step, the synthesis parameters (pH, AgNO3 concentration, ratio of bark extract and AgNO3, temperature, and reaction time) were optimized. The synthesized AgNPs were characterized by ATR-FTIR spectroscopy, DLS, SEM, EDX, and TEM. Their antioxidant, cytotoxic, and antibacterial properties were evaluated by the DPPH, ABTS, MTT, and broth microdilution assays, respectively. Abies alba and Pinus sylvestris bark extract-derived AgNPs were well-dispersed, spherical, small (average particle size of 9.92 and 24.49 nm, respectively), stable (zeta potential values of −10.9 and −10.8 mV, respectively), and cytotoxic to A-375 human malignant melanoma cells (IC50 = 2.40 ± 0.21 and 6.02 ± 0.61 μg/mL, respectively). The phytosynthesized AgNPs also showed antioxidant and antibacterial effects.

Extracts from parts of coniferous trees have received increased interest due to their valuable bioactive compounds and properties, useful for plenty of experimental and consolidated applications, in fields comprising nutraceutics, cosmetics, pharmacology, food preservation, and stimulation of plant growth. However, the variability of the bioactive properties, the complexity of the extraction methods, and the use of potentially harmful synthetic chemicals, still represent an obstacle to the spreading of such valuable natural compounds. Hydrodynamic cavitation is emerging as a promising innovative technique for the extraction of precious food components and by-products from waste raw material of the agro-food production chain, which can improve processing efficiency, reduce resource consumption, and produce healthy, high-quality products. In this study, a process based on controlled hydrodynamic cavitation was applied for the first time to the production of aqueous solutions of silver fir (Abies alba Mill.) needles with enhanced antioxidant activity. The observed levels of the in vitro antioxidant activity, comparable or higher than those found for reference substances, pure extracts, and other water extracts and beverages, highlight the very good potential of the hydrodynamic cavitation (HC) process for the creation of solvent-free, aqueous solutions endowed with bioactive compounds extracted from silver fir needles.

The dynamics of litterfall and its quantitative differentiation in stands with different species composition suggest that the origin of the organic matter accumulated in the organic horizons of forest soils affects their physical properties, and thus, their ability to retain rainwater. The main aim of the study was to determine the physical properties, the degree of decomposition and capillary capacity of individual ectohumus sublevels of mountain forest soils, formed under fir stands (Abies alba Mill.) and beech stands (Fagus sylvatica L.), and to compare them with the physical and retention properties of the organic horizons of spruce stands [Picea abies (L.) H. Karst], as determined by Kucza (2007). The study was conducted on soil monoliths, sampled in a way that allowed preserving their natural structure. For individual ectohumus sublevels contained in the monoliths, the content and degree of decomposition of organic matter, bulk density, total porosity and capillary capacity were determined. It has been shown that the capillary capacity of the litter layer (Ol) differed significantly between beech, fir and spruce stands, assuming average values equal to 1.60 (±0.10), 2.76 (±0.11) and 4.44 (±0.10) mm H₂O in the layer of 1 cm, respectively. In the case of detritus (Ofh) horizons, the smallest water storage capacity characterized beech stands, wherein the capillary capacity was approximately 1.39 mm lower than in fir stands and over twice lower as compared to spruce stands.

In forest ecosystems, the browsing activity of large wild herbivores (LWH) often leads to reduced tree and plant diversity, diminished biomass production, and challenges in achieving forest management objectives. Our case study focuses on assessing the impact of LWH browsing during the initial stages of forest growth by comparing fenced plots (F plots) with excluded LWH and control plots (C plots) with the presence of LWH. The experiment took place at the Hukavský Grúň research site in the Poľana Mts., characterized by a high red deer ( L.) population. Fifteen F plots and fifteen C plots, all situated within mixed maternal forests, were established in the 2023 growing season. Thus, circular plots with a radius of 2.5 m were utilized, and comprehensive data were collected on young trees (excluding those under 10 cm in height), covering tree species, positions, heights, and stem diameters. Species-specific allometric relations were employed to calculate the aboveground biomass of each tree, contributing to the overall biomass stock on a plot basis. A comparison between F and C plots revealed a prevalence of silver fir ( Mill.) in F plots, while European beech ( L.) dominated C plots. F plots exhibited higher tree species diversity (4.5 species), contrasting with the lower diversity (2.0 species) and absence of silver fir in C plots. The F plots also demonstrated greater tree density and sizes, resulting in substantial differences in aboveground biomass stocks. Browsing in C plots predominantly affected tree height rather than stem diameter, leading to a bigger height-to-diameter ratio in F plots compared to C plots. We suggest that fencing as a method to exclude LWH might be economically expensive and provide a temporary solution limited by the functionality of the fence. Therefore, the primary strategy for safeguarding the future of silver fir may lie in regulating LWH populations to a reasonable threshold.

Bio-passive samplers have proved to be good alternate to assess air quality in regions where the use of active samplers is not technically feasible. Here, we tested the potential for Abies alba (silver fir) needles to be used as reliable bio-passive samplers. As these evergreen coniferous trees do not lose their needles in winter these are representative of a full year period. Needle samples were collected in 2013 from 20 different locations within the Holy Cross National Park (Świetokrzyski Park Narodowy, Holy Cross Voivodship, Poland). Both needles and the aerosols deposited on their surfaces were analyzed for their δ 13 C. Additionally, total carbon (TC), elemental carbon (EC) and organic carbon (OC) were determined only in surface-impacted aerosols using thermo-optical method. The overall objective of our study was to evaluate the possibility to distinguish bio-organic aerosols (crushed needles) from anthropogenically derived aerosols. The highest aerosol mass concentration (4.6 ± 2.4 mg g −1 ) was observed in samples with the longest exposure time, while the shortest exposure times yielded the lowest ones (1.7 ± 0.7 mg g −1 ). Aerosols that were enriched in 13 C, indicating the impact of human activities, were located close to inhabited areas, at highly elevated points and in places situated outside the park. Our results also prove that one-year-old needles are the most reliable isotope bioindicators. We ultimately recommend that Abies alba needles can be used in future air quality monitoring programs, especially since this method is low cost and easy to implement.

As the outermost layer of stems and branches, bark is exposed to the influence of atmospheric conditions, i.e., to changes in the air’s relative humidity and wetting during storms. The bark is involved in water interception by tree canopies and stemflow generation, but bark–water relations are often overlooked in ecohydrological research and insufficiently understood. Relative to other canopy ecohydrological processes, little is known about vertical variation in bark properties and their effect on bark hydrology. Thus, the objective of this study was to analyze changes in physical properties (thickness, outer to total bark thickness ratio, density, and porosity) and hydrology (bark absorbability, bark water storage capacity, and hygroscopicity) vertically along stems of Norway spruce [ Picea abies (L.) Karst.] and silver fir ( Abies alba Mill.) trees. Our null hypotheses were that bark hydrology is constant both with tree height and across measured physical bark properties. We found that bark thickness and the ratio of outer-to-total bark thickness decreased with tree height for both species, and this was accompanied by an increase in the bark water storage capacity. In contrast, the bark’s density, porosity, and hygroscopicity remained relatively constant along stems. These results inform ecohydrological theory on water storage capacity, stemflow initiation, and the connection between the canopy water balance and organisms that colonize bark surfaces.

Abies alba Mill. (Pinaceae), silver fir, is a widespread gymnosperm species in Europe, important for its ecological, economic, social, and cultural significance, as well as for its use for food and bioremediation purposes. The various parts of the plant (leaves, branches, cones, wood, bark) are also of pharmaceutical interest due to their composition of active compounds. In the last three decades, an impressive amount of research has been dedicated to this species. The variability of the chemical composition of essential oils (whether they come from leaves, oleoresin from branches, or other parts of the plant) is impressive, even in the case of specimens collected from the same geographical area. For essential oils prepared from needles or twigs and branches, limonene, β-pinene, α-pinene, camphene, β-phellandrene, and bornyl acetate are the leading compounds, although their wide variations seem to correspond to multiple chemotypes. Both bark and wood are rich in lignans and phenolic compounds. Matairesinol is apparently the dominant lignan in bark, and secoisolariciresinol and lariciresinol are the dominant ones in wood samples. Pharmacological studies with promising results have evaluated the antioxidant effect (mainly due to essential oils), but also the antimicrobial, antitumor, probiotic, antidiabetic, anti-steatosis, and anti-psoriatic activities.

Interactions between tree species determine the dynamics of forest communities. Spatial and temporal changes in resource availability, variation in species composition and spatial distribution of trees may alter competitive interactions between species and, therefore, affect tree growth and forest productivity. In this study, we analyzed the intra and inter-specific interactions between European beech (Fagus sylvatica L.) and silver fir (Abies alba Mill.) in southern Italy (Molise and Calabria regions), and how these interactions affect basal area increments in mixed-species and pure stands. Results showed that intra-specific interactions have a negative effect on the basal area increment, both in pure and mixed-species stands of Molise and Calabria. Basal area increment was higher influenced by intra-specific interactions in pure stands than in mixed-species stands. Silver fir in Molise showed higher basal area increment in mixed-species stand, probably in relation with stand structure and space occupation that resulted in less competition between individual trees. European beech showed high values of intra-specific interactions in pure stands, likely related to the low self-tolerance of this species and to the spatial arrangement of trees, due to canopy closure. The absence of inter-specific interactions in mixed-species stands could be explained by the sub-dominant position of European beech, which may have limited the benefit derived from niche separation and complementarity for silver fir.