Pine Specimens Research Articles

Detection of Phytoplasma belonging to the 16SrXXI group in Scott pine and mountain pine

One of the reasons for the deterioration of coniferous stands condition in a number of European countries is associated with their infection with phytoplasmas (obligate intracellular pathogens) — bacteria lacking a cell wall. The aim of the work is to identify the presence of phytoplasma infection in samples of Scots pine (Pinus sylvestris L.) and mountain pine (Pinus mugo Turra) collected in the Moscow and Samara regions, which had characteristic symptoms of the disease, and to determine the taxonomic affiliation of the phytoplasm. Phytoplasma was detected using direct and nested PCR with primer pairs P1/16S-Sr and R16F2n/R16R2 respectively. Phytoplasma DNA was found in six of the seven pine specimens, including an asymptomatic one. Analysis of restriction fragment length’s polymorphism after digestion of DNA amplicons with restriction endonucleases AluI, MseI, HhaI, HpaII, HaeIII, RsaI, and TaqI indicated the similarity of Russian strains of Scotch pine and mountain pine phytoplasmas to Lithuanian strains of PineLRN and PineBLD of mountain pine phytoplasma (GenBank Accession Number MK089821 and MK089819, respectively) identified as ‘Candidatus Phytoplasma pini’ (subgroup 16SrXXI-A). A phytoplasma related to this species has been registered on the territory of the Russian Federation for the first time.

The effect of temperature and moisture content on drilling resistance measurements in wood (Pinus sylvestris L.)

ABSTRACT Drilling resistance (DR) measurements is widely used for nondestructive testing and evaluation of wood in growing trees and timber structures. A DR method can be applied in the regions with a cold climate and in wood with temperatures below zero degrees Celsius and varied moisture content (MC), which raises a question of correct interpretation of DR profiles and prediction of wood properties. Laboratory tests were conducted on Scots pine specimens with four levels of MC (7.4%, 11.0%, 23.5%, 147.9%) and temperature (+20°С, +2°С, −2°С, −10°С) variations. In-field tests were made on 33 growing trees at +18°С and −15°С. An IML-RESI PD 400 tool with a fixed rotational frequency of 2500 rpm and a feed rate of 1.5 m·min−1 was used. In most cases, wood temperature and MC had a significant influence on DR, but differences in an absolute value could be slight. A drastic increase in DR and feeding resistance was observed for water-saturated specimens tested at −10°C. For structural health assessment of timber structures at temperatures below 0°C, it is recommended to control wood MС. The effect of MC on DR was pronounced for groups of specimens with temperatures below and above the fibre saturation point. The in-field tests confirmed an increase in DR for frozen wood that can be used for studying water-conducting layers in growing trees.

Determination of the Dynamic Modulus of Elasticity of Pine Based on the PZT Transducer

A new method for the determination of the dynamic modulus of elasticity (Ed) of pine wood, based on the transverse vibration excitation and electromechanical impedance (EMI) response of the lead zirconate titanate (PZT) transducer is proposed. The influence of the length to thickness ratio of the pine specimen on the measurement accuracy was studied through modal simulation analysis. Based on the results of the modal simulation, the size of the pine specimen was optimized, and the scanning frequency range of the EMI response was determined. On this basis, the EMI simulation and test of the pine specimen coupled with a PZT patch were carried out to verify the effectiveness of the novel method. The impedance simulation results of three kinds of pine specimens show that a unique and significant formant appears in the real part of each EMI response curve, and the maximum relative errors of the rectangular PZT patch and circular PZT patch are 1.34% and 1.81%, respectively. The impedance test results of three kinds of pine specimens indicate that the maximum relative errors of the rectangular PZT patch and circular PZT patch are 1.41% and 1.68%, respectively, compared with the corresponding results obtained by the traditional transverse vibration method. Simulation and experimental results verify the validity of the proposed method for the elastic modulus determination of pine wood.

Effect of Wood Specimen Length on Uniaxial Stress–Strain Curve along the Grain Direction

Abstract The axial compression test was carried out on the basis of three different-size specimens of white wax (Fraxinus chinensis), fir (Abies fabri), and Yunnan pine (Pinus yunnanensis) to explore the influence of specimen length on the compression strength parallel to grain, peak strain, and elastic modulus of wood. Weibull’s weakest-link theory, Bazant’s law of size effect, and Carpinteri’s multiple fractal size effect were used for the analysis. The results showed significant size effects on theses parameters of wood along the grain. Using the three theories to predict the compressive strength of 100-mm-length specimens, the predicted value of Bazant’s law of size effect has the smallest error with the measured value, followed by Weibull’s weakest-link theory and Carpinteri’s law of multiple fractal size effect. The size-effect coefficients of the down-grain compressive strength of the three woods obtained using the slope method were 0.06, 0.11, and 0.09, respectively, which were consistent with the values of m in the Weibull fitting function.

Finger-jointed wood compressed parallel to the grain: Experiment and modelling

Compression tests of pine specimens of two types with initial dimensions of 40x40x80 mm and 40x40x80 mm with finger-joints are considered. Tests on similar specimens without finger-joints are also analyses for comparison. The experiments showed that the finger-joint in the investigated specimens reduced the peak load on the specimen as well as the load in the post-peak stage of plastic deformation. A methodology for modelling the load-displacement relationship taking into account the plastic deformation of wood with a finger-joint in the post-peak stage is proposed. The modelling results do not contradict the experimental data. The basic equation of the proposed mathematical model can be used in further studies to analyse the energy characteristics of the deformation process of wooden elements of building structures.

Effect of wetting and fungal degradation on the withdrawal capacity of stainless-steel screws in radiata pine

The effects of exposure to two decay fungi on the withdrawal capacity of stainless-steel screws inserted in the face and end grain of radiata pine specimens were assessed. Wetting followed by steam sterilization significantly increased capacity by 55–65%. Exposure to a brown (Fomitopsis ostreiformis) or white rot fungus (Pycnoporus coccineus) over 25 weeks was associated with 81–83% and 24–42% losses in withdrawal capacity, respectively. Comparison of experimental results with those predicted from design codes (Australia, Europe, US) showed an overestimation of the screw withdrawal capacity for the control specimens and highlighted the risk of strength degradation, especially in those specimens affected by brown rots.

Effects of anobiid damage on shear strength parallel to the grain in single step joints

Traditional carpentry joints can be found worldwide in many timber truss structures connecting rafter and tie beam. One failure mode of this connection result from shear in the tie beam beyond the notch either due to bad design or deterioration. In this article, the reduction in shear strength of Single Step Joints (SSJ) resulting from biological attack by anobiids was analysed. For this purpose, tests were carried out in non-degraded scots pine (Pinus sylvestris L.) specimens (reference) and compared to artificially degraded specimens with three different levels of degradation. The reduction of shear resistance was analysed in relation to the density of holes drilled during the degradation simulation, the loss of mass, and the reduction of the shear-resistant area. At lower degradation levels, no significant reduction in shear strength was observed. On the other hand, the linear regression shows a trend of resistance reduction with increasing degradation. Despite the relatively low coefficient of determination (r2 = 0.25), the parameter that best correlated with the residual strength was the reduction in the shear-resistant area.

The effect of the growth ring orientation on spring-back and set-recovery in surface-densified wood

Abstract Wood under thermo-mechanical densification behaves differently depending on the cross-sectional growth ring orientation (GRO) relative to the direction of compression. This influences the degree of cell damage, but also the shape-memory effects occurring when the compression load is released (spring-back) and when the timber is re-moistened (set-recovery). To study how the GRO influences the shape-memory effects, Scots pine specimens were separated into three distinct groups of GRO (Flat, Inclined, Hybrid) and then thermo-mechanically surface-densified. Spring-back and set-recovery were determined by thickness measurements and by digital image correlation. A GRO parallel to the densified surface, resulted in a low spring-back and a high set-recovery which were uniform over the width of the specimen. Specimens with a GRO between 15 and 45° to the densified surface showed high spring-back and low set-recovery, indicating cell-wall damage. Spring-back mainly occurred in the non-plasticised region immediately below the heated surface region and elasto-plastic rolling-shear deformation along individual growth rings occurred. The GRO of softwood subjected to thermo-mechanical densification determines if an applied load results in rolling shear-deformation or radial compression. This in turn determines where in the cross-section and when in the process the cells deform and if this deformation occurs below or above the glass-transition temperature.

Examination of the fire performance of wood materials treated with different precautions

This paper aims to discover how organic wood preservatives containing different fungicides and insecticides used to protect wood against fungal and insect pests affect the fire performance and combustion properties of wood materials commonly used in the domestic wood and construction industry. The aim of this article was to investigate the charring depth. From the point of view of the loss of load-bearing capacity of the wood, only the charring depth matters, since the reduction of the load-bearing capacity will be determined by the reduction of the cross section of the wood. We examined the effects of wood preservatives applied to undamaged samples of Scots pine and Norway spruce conditioned under normal climate conditions. The test samples underwent a second treatment application after which we examined the effect of different preservative combinations. Seven treatment mixtures were selected from the organic solvent and water-based wood preservatives available on the domestic market. The soaking experiments demonstrated that the preservative impregnation of Norway spruce differs significantly from that of Scots pine, which affected the comparability of the test results. We have experimentally investigated the moisture content, the loss of mass and we have calculated the char depth. Adhering to the MSZ 9607–1:1983 standard, the Linder method was performed to analyze the wood and wooden-based construction products used in construction. The effect of the different treatment materials was more significantly detectable when analyzing the size of the surface burn patterns. The Scots pine specimens suffered much greater surface burn than the Norway spruce specimens did, regardless of the type of preservative used. The higher body density, resin content (1–10%) and higher initial moisture content of Scots pine caused it to bend and, therefore, to burn better.

The effect of the changes in chemical composition due to thermal treatment on the mechanical properties of Pinus densiflora

Wood’s chemical composition has a close relationship to its mechanical properties. Therefore, chemical analysis such as FTIR spectroscopy offers a reasonable non-destructive method to predict wood strength. Pine (Pinus densiflora) specimens were thermal-treated in different conditions (aerobic and anaerobic) and evaluated by 3-point bending test for modulus of rupture (MOR) and by FTIR spectroscopy for chemical composition. Density and moisture content changes were also assessed in this study. The result showed that both density and equilibrium moisture content at 20 °C with 65 % humidity change little at low treatment temperatures, but they decrease at high treatment temperatures and when treated in the presence of oxygen. The MOR was improved by the reactions that occurred, including cellulose crystallisation, lignin condensation and cross-linking, whereas it was decreased by degradation reactions. The MOR were well predicted by two FTIR peak at 1318 cm−1 (relating to CH2 bond and condensation of G-ring of lignin), and at 1730 cm−1 (pertaining to changes to carbonyl groups in hemicelluloses) and density. It was concluded that FTIR spectroscopy provides a suitable method for wood non-destructive mechanical testing.

Providing a virtual material for simple estimation of fracture in U-notched highly orthotropic specimens with nonlinear behavior under mixed mode I/II loading

This research investigates the fracture toughness of U-notched Russian pine specimens with highly orthotropic nonlinear behavior under mixed mode I/II loading conditions theoretically and experimentally. The notch strength of orthotropic specimens is successfully predicted by introducing a novel two-step model of material simplification. Adopting this model, the nonlinear orthotropic material is equated with a virtual linear elastic isotropic material by coupling the Virtual Isotropic Material Concept and the Equivalent Material Concept. Therefore, the linear elastic notch fracture mechanics criteria, such as the mean stress and point stress models, can be basically employed to predict the notch fracture toughness of U-notched specimens made of nonlinear orthotropic material. Accordingly, the experimentally obtained notch strength of nonlinear orthotropic samples is predicted in the form of fracture limit curves and the curves of fracture initiation angle. It is shown that the two-step model proposed can be successfully applied for mixed mode I/II fracture estimation of notched orthotropic specimens with nonlinear behavior.

Using machine learning to predict the density profiles of surface-densified wood based on cross-sectional images

Over the past decades, the surface densification of solid wood has received increased attention. However, the inhomogeneous density distribution in the densification direction might be a challenge with regard to process control within a large-scale production process, as the density profile governs many relevant properties of surface-densified wood. Currently, the measurement of density profiles relies on sensitive X-ray equipment and is difficult to integrate into an on-line process. Hence, in this study, three machine learning approaches were applied to predict the density profiles of surface-densified Scots pine specimens, only based on visual image acquisition—a technology that is ubiquitous in the wood industry: partial least squares (PLS) regression, artificial neural networks (ANN), and convolutional neural networks (CNN). The machine learning models were trained on images of the specimen cross-sections as input data, and X-ray density profiles as output data. There were 1850 observations, and the model performance was evaluated on external test sets. The models had mean absolute percentage errors of the predicted values between 9 and 18%; the CNN achieving the smallest error (9.24%). A deeper analysis of the data revealed that the ANN approach performed inconsistently between observations. PLS regression predicted the main density peak to a high accuracy but could not model other features. Only the CNN could reliably model the main density peak, wide growth rings, and the important region between the specimen surface and the main density peak. The ability of the models to generalise to untypical new data was improved by augmentation of the training data.

Effects of Moisture and Direction of Grain on the Thermal Conductivity and Mechanical Properties of Black Alder and Scots Pine

Aim of study: Relationships between moisture content and thermal conductivity and mechanical properties of wood species were examined. Material and methods: Black Alder (Alnus glutinosa L.) and Scots Pine (Pinus sylvestris L.) specimens were used. Thermal conductivity, modulus of rupture, compression strength and impact bending strength values were determined and analyzed. All specimens were examined at 3 different moisture levels which are oven-dry, fiber saturation point (FSP) and completely wet. Main results: The lowest thermal conductivity value was found in the perpendicular to the grain direction of oven dried Black Alder samples as 0.119 W/mK. The highest thermal conductivity value was found in the parallel direction of Scots pine samples with FSP humidity content as 0.340 W/mK. In addition, the thermal conductivity value parallel to the grain is significantly higher than perpendicular one at all three moisture levels. Highlights: While there is a positive linear relationship between the moisture content of the wood and its dynamic bending resistance and thermal conductivity; It was found that there is a negative linear relationship between bending strength and compressive strength value.

Comparative study on weathering durability property of phenol formaldehyde resin modified sweetgum and southern pine specimens

Comparative study on weathering durability property of phenol formaldehyde resin modified sweetgum and southern pine specimens

Identifying southern yellow pine cross sections from the southeastern United States using quadratic discriminant analysis on pith and second annual ring diameters

Southern yellow pine specimens collected from historical structures, stumps, and coarse woody debris in forests have been difficult to identify at the species level due to similar wood anatomy. This can be problematic for dendrochronologists when identifying the correct species used in the construction of historical structures, or reconstructing forest history on the landscape and using those specimens in the context of that history. We applied a quadratic discriminant analysis (QDA) to update a century-old method plotting pith diameters against second annual ring diameters to discern one species of southern yellow pine from others. Our analysis estimates error rates for false positive and false negative determinations when comparing longleaf pine (Pinus palustris Mill.) to shortleaf (Pinus echinata Mill.) and loblolly pine (Pinus taeda L.). The cross-validated false positive error rates for the smallest dataset (n = 46), was nearly twice (9.52%) that determined as a simple proportion by counting errant observations (4.76%). QDA of the largest dataset (n = 206) gave a flatter zero contour and false positive rate (3.13%) like the proportionally determined value (1.56%), despite one additional observation being falsely assigned to longleaf pine by QDA. An unknown, unearthed southern pine specimen from southeastern Virginia was radiocarbon dated up to 500 years prior and assigned as longleaf by our method (probability ≥ 0.9998). Thus, through a QDA, it is possible to greatly improve confidence in identifications of key unknown specimens that can provide evidence of discerning one species, longleaf pine, from other southern yellow pines.

Fumigation of imported Tectona grandis and southern yellow pine with Pongamia pinnata seed oil against sapstain and mould

An eco-friendly alternative of Pongamia pinnata seed oil was tested for fumigation of imported Tectona grandis and Pinus spp. (Southern yellow pine) against sap stain and mould fungi at 25°C± 2°C and 75 % ± 5 % relative humidity. Veneeer and block samples of both species, and Petri dishes with agar media were fumigated with three different concentrations (w/v) of Pongamia pinnata seed oil and exhibited significant inhibition of fungal growth in comparison to the control sets, with the highest concentration of 6,4 g/ 8 mL3 proving to be the most lethal. Tectona grandis exhibited no infestation of sapstain and mould in either type of specimens whereas highly perishable Southern yellow pine displayed slight infestation of 4 % and 5 % with 1,6 g/ 2 mL3 of Pongamia pinnata seed oil for venner and block specimens as compared to 18 % and 20 % infestation observed in respective controls. The infestation on Southern yellow pine reduced to 1 % and 2 % respectively for veneers and blocks with 4 g/ 5 mL3 of Pongamia pinnata seed oil and was completely inhibited at 6,4 g/ 8 mL3 for both type of Southern yellow pine specimens. Petri plates returned similar findings where all higher concentrations inhibited mould growth completely and the lowest concentration exhibited meagre mould growth. Sapstain was inhibited successfully by all three concentrations of Pongamia pinnata seed oil on agar media.

Effect of thermal modification of slash pine with linseed oil on water repellency and performance of mechanical connections

Slash pine specimens were thermally modified at 120 and 160 °C in linseed oil for 2 and 6 h to determine the effects on water repellency and the impact on mechanical properties of nailed connections. Thermal modification improved water repellency. Results suggested the improvements were due to increased proportions of crystalline cellulose and lignin condensation. Mechanical tests of nailed connections showed a significant loss of performance only in samples treated at 120 °C for 2 h. The results indicate that thermal modification generally had no negative effects on connector behaviour.

A case-based reasoning method for discriminating damage levels in ancient wood components based on fuzzy similarity priority

In order to rapidly identify internal damage levels accurately in ancient wood components, stress wave detection technology was used to perform simulated damage tests on pine specimens. Based on the detected wave velocity data, the diameter of the specimen, the attenuation coefficient, and the ratio of the wave velocities on the four paths were selected as the discriminant factors for identifying the level of internal damage in the specimens. A case-based reasoning method for discriminating internal damage levels in ancient wood components based on fuzzy similarity priority was proposed. A fuzzy similarity priority relationship between the target case and the source case was established. By introducing the idea of variable weights, the weight of each discriminant factor was determined via the “penalize-excitation” variable weight function. The comprehensive similarity sequences between the target case and the source case were obtained. The source case that was most similar to the target case was used to determine the damage level of the target case. The results showed that this method can quickly and accurately identify the damage levels in ancient wood components, which provides a new method for the safe evaluation of ancient wood buildings.

Weathering characteristics of impregnated and coated Calabrian pine wood

This study was designed to investigate the weathering characteristics of Calabrian pine (Pinus brutia) wood. The wood specimens were impregnated with some copper-based chemicals and then varnish coated. As copper-based chemicals, Celcure C4, Korasit KS, and Tanalith E 8000 were used for impregnation. Polyurethane varnish (PV) and water-based varnish (WBV) were used as coating materials. Firstly, Calabrian pine wood was impregnated with 2,5 % and 5 % aqueous solutions of chemicals then coated with polyurethane varnish and WBV. Impregnated and coated Calabrian pine wood specimens were subjected to 6 months of natural weathering in Mugla, Turkey. After weathering; surface hardness, surface roughness, and adhesion strength changes of Calabrian pine wood specimens were determined. Impregnation caused to increase in surface hardness values of Calabrian pine. Surface hardness increases of water-based varnish coated Calabrian pine specimens were higher than polyurethane varnish coated Calabrian pine specimens. Impregnation resulted in higher surface roughness values of Calabrian pine specimens. Polyurethane varnish coated Calabrian pine specimens gave higher surface roughness than water-based varnish coated Calabrian pine specimens. The adhesion strength values of all treatment groups were decreased after weathering. In general, adhesion strength decreases of water-based varnish coated Calabrian pine specimens were higher than that of polyurethane varnish coated Calabrian pine specimens. The concentration levels of chemicals did not have a significant effect on surface roughness and adhesion strength of Calabrian pine wood after weathering

Yellow Pine Small Clear Flexural Properties across Five Decades

Abstract When discussing structural southern yellow pine lumber, questions frequently are asked regarding changes over time. This is a significant area of discussion given that structural lumber properties (i.e., design values) were changed around 2012. Climate change, forest management, genetics, processing, and others are listed among the many possible contributing factors. Of interest are these questions: (1) Are changes in bending properties permanent at some fundamental level, or are they somewhat dynamic and responsive to controllable factors? (2) To what degree have the basic southern pine wood mechanical properties changed over time? Related thereto, this research examines the bending properties of small clear pine specimens from three samples. Sample 1 was pulled from a production-weighted sample of in-grade parent lumber. Sample 2 was pulled from commercially available molding and millwork. Sample 3 was pulled from data from the U.S. Department of Agriculture Forestry Products Laboratory from the early to mid-1960s. The flexural properties of small clear specimens among the three samples showed some statistically significant differences. However, there was no clear trend regarding these differences. These results appear to support the notion that while the variability of pine's flexural properties is significant and that while many changes in forest management and production have occurred over the past five decades, the basic density and bending strength of clear southern pine appear generally stable over time.