How Bark Beetle Attack Changes the Tensile and Compressive Strength of Spruce Wood (Picea abies (L.) H. Karst.)

Since 2014, forestry in the Czech Republic has been significantly affected by a bark beetle outbreak. The volume of infested trees has exceeded processing capacity and dead standing spruce (Picea abies) remain in the forest stands, even for several years. What should be done with this bark beetle wood? Is it necessary to harvest it in order to preserve the basic mechanical and physical properties? Is it possible to store it under standard conditions, or what happens to it when it is “stored” upright in the forest? These are issues that interested forest owners when wood prices were falling to a minimum (i.e., in 2018–2019) but also today, when the prices of quality wood in Central European conditions are rising sharply. To answer these questions, we found out how some of the mechanical properties of wood change in dead, bark beetle-infested trees. Five groups of spruce wood were harvested. Each of these groups was left upright in the forest for a specified period of time after bark beetle infestation, and one group was classified as a reference group (uninfested trees). Subsequently, we discovered what changes occurred in tensile and compressive strength depending on the time left in the stand and the distance from the center of the trunk. When selecting samples, we eliminated differences between individual trees using a CT scanning technique, which allowed us to separate samples, especially with different widths of annual rings and other variations that were not caused by bark beetle. The results showed the effect of log age and radial position in the trunk on tensile and compressive strength. The values for tensile strength in 3-year infested trees decreased compared to uninfested trees by 14% (from 93.815 MPa to 80.709 MPa); the values for compressive strength then decreased between the same samples by up to 25.6% (from 46.144 MPa to 34.318 MPa). A significant decrease in values for compressive strength was observed in the edges of the trunks, with 44.332 MPa measured in uninfested trees and only 29.750 MPa in 3-year infested trees (a decrease of 32.9%). The results suggest that the use of central timber from bark beetle-infested trees without the presence of moulds and fungi should not be problematic for construction purposes.

Fire Parameters of Spruce (Picea abies Karst. (L.)) Dust Layer from Different Wood Technologies Slovak Case Study

The issue of the formation of wood dust particles in the work environment is still an actual topic in terms of its impact on employee health and the risk of fire or explosion in a woodworking operation. This article deals with the characteristics of spruce dust (Picea abies Karst. (L.)), which was taken from several types of wood technology. Experimental samples of spruce dust were taken from four types of sawing technologies, including grinding, briquetting and from the suction device container. The physical parameters of the samples taken were monitored and the particle size analysis was determined. The granulometric composition of the samples is significantly different. The sample of spruce wood dust from sawing has the most numerous fraction (250 µm), while the sample from grinding has the most numerous fraction 63–250 µm (87%).The aim of the paper was to monitor the minimum ignition temperature of the settled spruce dust layer and to look for a significant dependence of the minimum ignition temperature and ignition time on the type of spruce dust sample. A significant dependence was not confirmed. Significant moisture dependence of the samples was confirmed; the highest humidity was observed in the container, the lowest in sawing.

Biochemical indicators of woody plants in the diagnosis of air condition

It is found that anthropogenic pollution has a significant effect on the change in the content of total nitrogen, glutathione and vitamin E, which increases the resistance of woody plants to stress. A series of woody plants with regard to their sensitivity to aerosol pollution has been compiled: according to the degree of decrease in total nitrogen – Picea abies > Thuja occidentalis > Syringa vulgaris > Acer platanoides > Tilia cordata > Sorbus aucuparia; the degree of decrease in glutathione content – Picea abies > Thuja occidentalis > Syringa vulgaris > Acer platanoides > Tilia cordata > Sorbus aucuparia; the degree of decrease in the content of vitamin E – Picea abies > Thuja occidentalis > Sorbus aucuparia > Tilia cordata > Syringa vulgaris > Acer platanoides. A positive correlation was revealed between the biochemical parameters of woody plants and the monitoring complex indices proposed by the Russian meteorological service. A close direct regression dependence of the air pollution index and the average stability coefficient for the content of total nitrogen, vitamin E and glutathione in the biomass of model woody plants was revealed: with an increase in the degree of air pollution, the average stability coefficient for certain biochemical indicators increases.

Cytogenetic characteristics of seed progeny of old-aged trees of Pinus pallasiana and Picea abies (Pinaceae)

Information on cytogenetic changes in the seed offspring of old-aged trees is insufficient and inconsistent. In our studies, 150–200-year old trees of Picea abies and Pinus pallasiana were used. We analyzed peculiarities of their karyotype, nucleus-forming region, and nucleolus in the cells of seedlings of P. abies and P. pallasiana emerged from seeds in natural populations and plantations of introduced plants. As a result, age-dependent cytogenetic disorders were observed, such as the chromosome bridges, lag, premature segregation, and agglutination. Peculiarities with regard to number and structure of secondary chromosome constriction are demonstrated. The identified properties of the cell structure of seeds of old-aged trees of P. abies and P. pallasiana indicate that more resources are needed to maintain their protein synthesis at a normal level. The increased number of abnormalities indicates a significant impact of accumulated intracellular metabolites and cytopathological phenomena in mother plants on the quality of seed offspring.

Phyto-Functionalized Silver Nanoparticles Derived from Conifer Bark Extracts and Evaluation of Their Antimicrobial and Cytogenotoxic Effects

Silver nanoparticles synthesized using plant extracts as reducing and capping agents showed various biological activities. In the present study, colloidal silver nanoparticle solutions were produced from the aqueous extracts of Picea abies and Pinus nigra bark. The phenolic profile of bark extracts was analyzed by liquid chromatography coupled to mass spectrometry. The synthesis of silver nanoparticles was monitored using UV-Vis spectroscopy by measuring the Surface Plasmon Resonance band. Silver nanoparticles were characterized by attenuated total reflection Fourier transform infrared spectroscopy, Raman spectroscopy, dynamic light scattering, scanning electron microscopy, energy dispersive X-ray and transmission electron microscopy analyses. The antimicrobial and cytogenotoxic effects of silver nanoparticles were evaluated by disk diffusion and Allium cepa assays, respectively. Picea abies and Pinus nigra bark extract derived silver nanoparticles were spherical (mean hydrodynamic diameters of 78.48 and 77.66 nm, respectively) and well dispersed, having a narrow particle size distribution (polydispersity index values of 0.334 and 0.224, respectively) and good stability (zeta potential values of −10.8 and −14.6 mV, respectively). Silver nanoparticles showed stronger antibacterial, antifungal, and antimitotic effects than the bark extracts used for their synthesis. Silver nanoparticles obtained in the present study are promising candidates for the development of novel formulations with various therapeutic applications.

Analysis of the polymorphism of microsatellite loci in Picea abies (L.) H. Karst. and Picea obovatа Ledeb populations

Процессы генезиса хвойных лесов интенсивно изучаются с использованием методов молекулярного маркирования. Микросателлитные локусы рассматриваются в качестве наиболее полиморфной и воспроизводимой системы кодоминантных молекулярных маркеров. В цели исследования входило установить возможность использования микросателлитных маркеров для определения видовых различий между елью европейской и сибирской (Picea abies и Picea obovatа), а также оценить степень генетической обособленности региональных популяций ели на территории Европейской части РФ. Исследование показало, что использование набора из двенадцати микросателлитных маркеров позволяет разделить выборку елей, собранных с европейской и азиатской частей страны, на два генетических кластера, соответствующих видам Picea abies и Picea obovatа. Проанализированные в исследовании микросателлитные локусы могут быть использованы для оценки генетического разнообразия и географического происхождения ели европейской и сибирской. The processes of genesis of coniferous forests are widely investigating using molecular markers. Many studies are based on the analysis of microsatellite loci, which are acknowledged as the most reproducible and polymorphic co-dominant molecular markers. This study is aimed to establish the possibility of using microsatellite markers to determine differentiation between Norway and Siberian spruce (Picea abies and Picea obovata). Another task of this research was to assess the degree of genetic isolation of regional spruce population in the territory of European part of the Russian Federation. This study shows that using a large number of microsatellite markers allows to divide the sample of spruce collected from European part of Russia and Siberia in two genetic clusters, corresponding to Picea abies and Picea obovata. The microsatellite loci analyzed in the study can be used to assess genetic diversity and geographic origin of spruce trees and determine the origin of wood and planting material of Norway and Siberian spruce.

Comparative analysis of genetic diversity in Norway spruce (Picea abies) clonal seed orchards and seed stands

Norway spruce, Picea abies (L.) Karst. is the most important conifer species in Romania and the most planted tree species in the Carpathian Mountains. Here we compare the genetic diversity of four Norway spruce clonal seed orchards and two seed stands located in the Eastern Carpathians. A set of highly polymorphic nuclear microsatellite markers was used. The analysis of genotypic identity of ramets for each Norway spruce clone in all seed orchards indicated that nearly all sampled ramets (97%) were genetically identical. The genetic diversity in seed orchards (He=0.700) was slightly smaller compared to the seed stands (He=0.718). Allelic richness was higher in seed stands (10.874), compared to clonal seed orchards (8.941). The Bayesian analysis indicated a genetic structure with two clusters, one corresponding to the clonal seed orchards and a second one consisting of the two seed stands. Our results provide valuable information for the management of Norway spruce seed orchards in Romania.

Selected Properties of Cement Bound Spruce and Larch Bark Bio-Aggregates

The aim of this study is to investigate the suitability of spruce and larch bark for the production of cement-bonded composites. At the beginning of this research, the curing behaviour of the admixtures was quantified with temperature profiles when testing spruce, larch, pine and poplar bark, to determine the compatibility between the components of the bio-aggregates, to analyse the cement curing and to establish which bark species should be successfully included in cement bonded composites. Considering the results, it was observed that the average densities of 600–700 kg/m3 of bio-aggregates are 40–55% lower than that of established products on the market, although spruce and larch bark are in a similar range. The situation is different for the compressive strength, as larch bark showed up to 30% higher values than spruce bark. This study revealed also different hardening characteristics of the two cement types used as binders for spruce and larch bark. The results of this study demonstrated that tree bark of Picea abies and Larix decidua Mill. can be successfully utilized for the production of a cement-bonded composite material.