Impact of fixation/drying conditions on fixation rate, teachability and bioefficacy in CCA-C treated red pine and southern pine

Red pine (Pinus resinosia Ait) and southern pine (Pinus spp.) sapwood blocks were pressure treated with CCA-C at retention of 6.4, 2.0, 1.5 kgm^-3 followed by fixation using 11 post-treatment schedules ranging from 50–70 °C and 5 different relative humidity conditions. The effect of these post-treatment schedules on fixation rate, chemical leachability and decay resistant once were evaluated to better understand the effects of fixation/drying conditions on leachability and biodeterioration. Southern pine blocks fixes slightly slower than red pine. Fixation of CCA at high temperature high humidity, essential initially fixation at high humidity for fixation/drying schedules, resulted in lower leaching of chromium and arsenic elements than high temperature low humidity or initially fixation at the high temperature low humidity conditions. Copper leaching was indicated no significant difference under 11 fixation/drying conditions for both species. Weight losses for southern pine byChaetomium globosum was lower than red pine byGloeophyllom trabeum. There were some different capacities of decay resistance for both species under those post treatment conditions.     

Impact of fixation/drying conditions on fixation rate, leachability and bioefficacy in CCA-C treated red pine and southern pine

Red pine (Pinus resinosia Ait) and southern pine (Pinus spp.) sapwood blocks were pressure treated with CCA-C at retention of 6.4, 2.0, 1.5 kg?m-3 followed by fixation using 11 post-treatment schedules ranging from 50-70 °C and 5 different relative humidity conditions. The effect of these post-treatment schedules on fixation rate, chemical leachability and decay resistant once were evaluated to better understand the effects of fixation/drying conditions on leachability and biodeterioration. Southern pine blocks fixes slightly slower than red pine. Fixation of CCA at high temperature high humidity, essential initially fixation at high humidity for fixation/drying schedules, resulted in lower leaching of chromium and arsenic elements than high temperature low humidity or initially fixation at the high temperature low humidity conditions. Copper leaching was indicated no significant difference under 11 fixation/drying conditions for both species. Weight losses for southern pine by Chaetomium globosum was lower than red pine by Gloeophyllom trabeum. There were some different capacities of decay resistance for both species under those post treatment conditions.     

固化干燥条件对CCA-C处理(北美)红松和南洋松木材的固化速度和流失特性的影响(英文)

该文使用 6 4kg·m-3 的CCA C木材防腐剂 ,在 11个后处理基准 (其温度为 5 0℃～ 70℃和 5个不同的相对湿度 )条件下 ,研究了固化干燥条件对处理北美红松和南洋松木材的固化速度和化学元素的流失的影响 .实验样品内的液体通过挤压方法被定期检测并分析其六价铬的含量 .调节固化后的样品按美国木材防腐协会E11 97标准进行流失实验 .一般情况下 ,对于大多数基准 ,红松固化比南洋松少、快 ,并且高温高湿的固化条件比低湿度的固化条件导致较快的固化速度和较少的铬和砷的流失 .对于2个材种在 11个固化干燥条件下 ,铜元素的流失没有很大的差异 .所有的CCA化学元素的流失情况 ,红松比南洋松更明显 .更进一步的工作需要CCA处理大尺寸样品 ,优化干湿球温度差 ,以便考察其固化干燥条件对流失的影响     

Efficacy of radio frequency treatment and its potential for control of sapstain and wood decay fungi on red oak,poplar, and southern yellow pine wood species

The effectiveness of radio frequency (RF) treatment in the control of wood decay fungi (Gloeophyllum trabeum, Ganoderma lucidum, and Irpex lacteus) and sapstain fungus (Ceratocystis fimbriata) in red oak (Quercus spp.), poplar (Populus alba), and southern yellow pine (Pinus spp.) was evaluated in the laboratory as an alternative to methyl bromide (MB) treatment. Wood samples (15.5 x 10 x 10 cm) were inoculated with fungi from a 7-day culture by dipping them to a depth of one face deep (2 cm) into inoculum and incubating them at 25°C for 14 days. Identical wood samples were left uninoculated as controls. Subsequent to incubation, the wood blocks were exposed to RF radiation in an industrial 40-kW dielectric oven at temperatures between 60° and 70°C for 2 min. The test fungi were recovered and reisolated from all of the control wood blocks but not from RF-treated wood blocks. RF treatment resulted in complete inhibition of the fungus in 98%-100% of the wood samples. Moisture content loss (≥1%) was noted after wood had been exposed to RF treatment. Moisture content may be an important factor to consider with RF treatments. RF treatment can, therefore, potentially provide an effective and rapid quarantine treatment as an alternative to MB fumigation for certain pathogen-wood combinations. This article reports the results of research only. Mention of a product does not constitute an endorsement or recommendation by USDA for its use.     

Corrosion of metal fasteners embedded in acetylated and untreated wood at different moisture contents

ABSTRACT

Acetylated wood is now commercially available and designed to be used in certain outdoor applications as an alternative to preservative-treated wood. Fastener corrosion can be a concern in preservative treated wood when the wood remains wet for long periods. However, little data on the corrosiveness of acetylated wood exists beyond the product literature. Here we examine the corrosiveness of commercially obtained acetylated wood and compare it against unmodified (untreated) southern pine (Pinus spp.). Corrosion rates of plain carbon steel, hot dip galvanized steel, and stainless steel were calculated gravimetrically after a one year exposed in the wood. Four different moisture conditions were examined: 90% relative humidity (RH), 95% RH, 100% RH, and a fully water saturated condition. When compared to literature data on the corrosion of fasteners in preservative treated wood at 100% RH, the acetylated wood had much lower steel corrosion rates than all preservatives examined; the measured corrosion rates for galvanized steel were lower than all preservatives except chromated copper arsenate. These measured corrosion rates across a range of moisture conditions can be used to inform the selection of appropriate corrosion resistant fasteners when building with acetylated wood.     

Durability of thermally modified Norway spruce and Scots pine in above-ground conditions

Abstract

One of the main objectives of thermal modification is to increase the biological durability of wood. In this study the fungal resistance of Norway spruce and Scots pine, thermally modified at 195°C and 210°C, was studied with a lap-joint field test. Untreated pine and spruce and pine impregnated with tributyl tin oxide (TBTO) and copper, chromium and arsenic (CCA) were selected as reference materials. The evaluations were carried out after 1, 2 and 9 years of exposure. After 1 and 2 years of exposure mainly discoloration was detected. Only the untreated pine was slightly affected by decay fungi. There were significant differences in the decay ratings of untreated and thermally modified wood materials after 9 years in the field. While the untreated wood materials were severely attacked by decay fungi or reached failure rating, only small areas of incipient decay were detected in the thermally modified samples. Thermally modified pine was slightly more decayed than thermally modified spruce. The only wood material without any signs of decay was CCA-treated pine, since some of the TBTO-treated pine samples were also moderately attacked by fungal decay. The results of the lap-joint test had a good correlation with mass losses in a laboratory test with brown-rot fungi.     

Evaluation of the temperature and relative humidity preferences of the western dry-wood termite <Emphasis Type="Italic">Incisitermes minor</Emphasis> (Hagen) using acoustic emission (AE) monitoring

Twenty-four different combinations of six temperatures (15°, 20°, 25°, 30°, 35°, and 40°C) and four relative humidity (RH) (60%, 70%, 80%, and 90%) conditions were used for pseudergates of the western dry-wood termite Incisitermes minor (Hagen). The feeding activities of the termites were monitored by the detection of generated acoustic emission (AE) events from feeder wood blocks in a test chamber. Temperature and RH showed independent and interactive significant effects on the feeding activity of I. minor. The optimal temperature and RH conditions for the feeding activities were 35°C and 70%, respectively, and the optimal combinations were 35°C-70% and 35°C-80% with an exceptionally higher feeding activity at the combination condition of 30°C-70%.     

Moisture storage and transport properties of preservative treated and untreated southern pine wood

Moisture storage and transport properties of southern pine (Pinus spp.) wood were measured for implementation into hygrothermal models. Specimens were untreated or pressure-treated with alkaline copper quaternary (ACQ) preservative. Moisture storage was characterized with sorption isotherms in the hygroscopic region (high capillary pressures) and documented with mercury intrusion porosimetry in the overhygroscopic region (low capillary pressures). The data were then combined into a single moisture retention curve as a function of capillary pressure. Moisture transport was evaluated from steady-state water vapor transmission and dynamic capillary water absorption experiments. These data were used to calculate the moisture permeability over the entire range of capillary pressures using the diffusivity approach of Carmeliet et al. Moisture storage and transport properties were similar for the untreated and ACQ-treated southern pine, except for the permeability of the treated wood which was lower in the radial direction. The data presented here can be used to improve the accuracy of hygrothermal and combined hygrothermal–corrosion modeling simulations.     

Modeling of simultaneous unidirectional leaching and reduction of Cr<Superscript>6+</Superscript> in unfixed CCA treated wood

The unidirectional leaching of unfixed hexavalent chromium (Cr⁶⁺) from wood freshly treated with chromated copper arsenate (CCA) is modeled as simultaneous diffusion and first-order chemical fixation reaction. Small wood specimens were coated to restrict preservative movement to one direction, then treated with CCA and immersed in water to evaluate unidirectional leaching characteristics. The directional diffusion coefficients and reaction rate constants of Cr⁶⁺ in unfixed CCA-treated red pine (Pinus resinosa Ait.) and southern pine (Pinus sp.) were estimated by least squares fitting of the model to leaching results in each direction independently. The reaction rate constants calculated from the diffusion and leaching model were generally consistent with results from pure fixation experiments, although the computed rate constants increased under the most severe longitudinal leaching conditions. The applicability of using diffusion coefficients and rate constants estimated from leaching results was tested using a finite difference implementation of the diffusion and reaction model to predict unidirectional leaching from small samples immersed intermittently in water. The predicted leachate quantities were consistent with experimental measurements at the end of each of five leaching events of various durations at temperatures alternating between 13 and 23°C over a 9-day period.     

Persistence of some pine pathogens in coarse woody debris and cones in a Pinus pinea forest

The persistence of Sphaeropsis sapinea, Leptographium serpens and Heterobasidion annosum s.s. in artificially inoculated pine branch pieces (S. sapinea and L. serpens) and wood blocks (L. serpens and H. annosum s.s.) was investigated in order to discuss the alternative of leaving coarse woody debris in stands of Italian stone pine (Pinus pinea). Also, natural colonization by S. sapinea of pine cones of different ages was assessed. Methods used for inoculating branch pieces and wood blocks were highly effective for all fungi. Type of a forest stand in which branch pieces and wood blocks have been incubated did not affect the persistence of the pathogens in the inoculated samples. For branch pieces, the success of re-isolation of L. serpens dropped as the sample incubation time increased, while S. sapinea was always successfully (100%) re-isolated (even 12 months after the inoculation). L. serpens and H. annosum s.s. were re-isolated from most of the buried wood blocks (from more than 95% samples) up to 3 months following the inoculation. Of the observed P. pinea cones (in most cases, more than 2 years old), 74% were naturally infected byS. sapinea. All three investigated pathogens were able to survive in dead plant tissues for long periods of time (at least for several (3–12) months). The persistence of these pine-pathogenic species in dead plant material questions the feasibility of leaving coarse woody debris in managed Italian stone pine forests meant for landscape conservation and leisure activities.     

Swedish lodgepole pine seed orchard crops tested in north-west Russia

Abstract

Tree vitality and height of lodgepole pine (Pinus contorta var. latifolia) originating from the six Swedish seed orchards and native Scots pine (Pinus sylvestris L.) were estimated in three 8-yr-old test plantations established in the Komi Republic (north-west Russia). A randomized row-plot design with 9–13 replicates of each entry was used. In general, the Scots pine tree vitality was better than that of lodgepole pine but these differences were significant only for seed sources of southern origins Larslund, Rumhult, and Österby. On the contrary, the lodgepole pine height growth was faster (6–21%) except for seed sources of southern origins Rumhult and Österby. In comparison with the native Scots pine, lower mean heights (4–10%) were recorded for these seed sources. Among the lodgepole pine seed sources the northern origins had better vitality, while the effect of latitude on the tree height was insignificant.     

Effect of spacing on 23-year-old lodgepole pine (Pinus contorta Dougl. var. latifolia) in southern Sweden

Abstract

The objective of this study was to compare volume growth and external timber quality properties of lodgepole pine (Pinus contorta Dougl. var. latifolia) stands planted in different spacings (1.41×1.41, 2.00×2.00, 2.83×2.83, 4.00×4.00) in southern Sweden. In northern Sweden lodgepole pine has been grown for a long time and shows superior volume production compared to Scots pine (Pinus Sylvestris L.). The Swedish Forestry Act restricts establishment of lodgepole pine plantations in southern Sweden. However, it is important to increase the knowledge about lodgepole pine and its potential use also in this part of the country. Two experiments in southern Sweden were studied. Each trial was designed as a random block experiment with two blocks. Both investigated stands had an age of 23 years at the time of assessment. The mean diameter and the volume production differed significantly between the spacings. The highest volume production was found in the narrowest spacing, 313% compared to the widest spacing. Significant differences between spacings were also found concerning external quality traits. The frequency of dominant and co-dominant trees without defects was 24% in the most open spacing compared to 46% in the narrowest one. Under current circumstances approximately 2500 seedlings/ha in the initial stand seems to be a reasonable compromise between growth, diameter development and timber quality.     

Mycologg: a new accelerated test method for wood durability above ground

If not properly handled, selected and protected, wood will be degraded by bacteria, fungi and also insects. In order to ensure service life, durability tests are needed. Most accelerated laboratory tests on wood durability are focused either on fungi attacks or the uptake of moisture. Accelerated field tests in ground contact are of limited use since they could be difficult to reproduce and are sensitive to the characteristics of the soil in which the wood is placed. In addition, the results cannot be directly transferred to wood in use above ground because such wood is subjected to different set of conditions. The Mycologg is a new accelerated test method for estimating the durability of wood in above ground applications. The Mycologg allows the test panels to be subjected to the discolouring fungi and different RH (relative humidity) cycles simultaneously. Every 30 min, the temperature, the RH, and the moisture content in each test panel are measured and saved in special software. This allows for a constant update of the moisture patterns during a fungi attack. A trial was made with Scots pine (Pinus sylvestris) heartwood samples, where fungal growth after 6, 8 and 10 weeks in the Mycologg were compared to weather exposure of duplicate samples after 12, 16, and 26 months. The results showed that 10 weeks into the Mycologg accelerated test method corresponds well to real-time weather exposure with respect to fungal discolouration.     

Responses of water-stressedPinus thunbergii to inoculation with avirulent pine wood nematode (Bursaphelenchus xylophilus): Water relations and xylem histology

The effect of water-stress conditioning on water relations and histological features ofPinus thunbergii Parl. inoculated with avirulent isolate ofBursaphelenchus xylophilus (Steiner and Buhrer) Nickle, pine wood nematode, were investigated. Pines were kept under 8 days cycle of severe water stress. One-half of the water-stressed pines died as a result of infection by avirulent pine wood nematode and water stress tended to induce increased susceptibility and/or decreased resistance of pines to avirulent pine wood nematode. In dead pines, the water conducting function of xylem was lost, and all of the parenchyma cells died. In surviving pines, the xylem hydraulic conductivity and the xylem water content were significantly reduced (12 to 23% and 77 to 83%, respectively) compared to controls. Safranin dye perfusion of excised axis stem segments indicated that the water conductance was limited to the very narrow peripheral area of xylem. Embolism caused by cavitation in the tracheids occurred in the central part of xylem and in that dysfunctional region of the xylem the axial parenchyma cells surrounding the epithelial cells, and ray parenchyma cells partly degenerated but the epithelial cells survived. The disruption of tracheid shape observed in surviving pines indicates that avirulent pine wood nematode temporarily disturbed cell division of the cambium. Considering the differences in responses between dead pines and surviving pines after inoculation with avirulent pine wood nematode, the death of water-stressed pines apparently resulted from death of cells, in particular the vascular cambium and the loss of xylem hydraulic function by cavitation.     

Potential use of visible and near-infrared spectroscopy for pine species discrimination by examination of needles

The correct identification of pine species is necessary for proper application of wood in forest?based industries, since the quality of each species’ wood depends on factors intrinsic to the material. The aim of this study was to evaluate the potential use of near?infrared and visible spectroscopy in the discrimination of pine species planted in southern Brazil. Needles of Pinus clausa, P. glabra, P. kesiya, P. oocarpa, P. palustris, P. pseudostrobus, P. rigida, P. roxburghii and P. serotina were collected from experimental plantations located in the region of Rio Negro, Paraná, Brazil. The needles were dried and milled for analysis. The evaluation was performed with a spectral range of 400–750?nm (visible) and 1 000–2 500?nm (near?infrared). Analysis using the visible spectra resulted in two principal components explaining 95% of the variation between the needle samples. In the near?infrared analysis, it was possible to discriminate between all nine pine species studied using only two principal components, where the first explained 99% of the variation between species. Spectroscopy based on needles can be used for pine species discrimination, using the original data without mathematical treatment, in southern Brazil.     

Colour responses from wood,thermally modified in superheated steam and pressurized steam atmospheres

Abstract

In this study, two different methods were used to produce thermally modified wood. One was carried out in a typical kiln drying chamber using superheated steam (SS) and the other used pressurized steam in an autoclave cylinder (PS). Overall, both processes followed the same principles and the wood was not treated with any chemicals. Two wood species were studied, Scots pine (Pinus sylvestris) and Norway spruce (Picea abies). Treatments in the autoclave were carried out under pressure using temperatures of 160°C, 170°C and 180°C. Temperatures of 190°C and 212°C were used in treatments in the chamber at normal air pressure. The colour was measured using L*C*H colour space. Results for both species showed that similar L* (lightness) can be reached at lower (20–30°C) temperatures using PS compared with SS treatment. The hue angle of PS-treated wood was smaller than that of SS-treated wood. No significant difference in C* (chroma) was detected. The difference in E value between PS- and SS-treated wood was smaller for Norway spruce than for Scots pine. The residual moisture content was about 10% higher in wood treated by the PS process compared with the SS process.     

Crystalline structure of heat-treated Scots pine [<Emphasis Type="Italic">Pinus sylvestris</Emphasis> L.] and Uludağ fir [<Emphasis Type="Italic">Abies nordmanniana</Emphasis> (Stev.) subsp. <Emphasis Type="Italic">bornmuelleriana</Emphasis> (Mattf.)] wood

The aim of this study was to determine changes in crystallinity and crystalline unit cell type of heat-treated Scots pine (Pinus sylvestris L.) and Uludağ fir (Abies nordmanniana stev. subsp. bornmuelleriana Mattf.) wood samples by means of FT-IR spectroscopic method. Heat treatment was applied on the test samples in an oven at three different temperatures (120, 150, and 180°C) and for two different periods of time (6 and 10 h) under atmospheric pressure. It was designated that crystallinity of both Scots pine and Uludağ fir wood samples increased during heat treatment depending on the duration. However, monoclinic structure in crystalline unit cells of Scots pine and Uludağ fir wood samples converted to triclinic structure when heat treated. It was estimated that monoclinic structure was dominant in the crystalline unit cell. It was established that the crystalline structure of Scots pine wood samples was more affected by heat treatment than that of Uludağ fir wood samples.     

Effects of impregnation and heat treatment on the physical and mechanical properties of Scots pine (Pinus sylvestris) wood

Wood modification, of which thermal modification is one of the best-known methods, offers possible improvement in wood properties without imposing undue strain on the environment. This study investigates improvement of the properties of heat-treated solid wood. Scots pine (Pinus sylvestris) was modified in two stages: impregnation with modifiers followed by heat treatment at different temperatures. The impregnation was done with water glass, melamine, silicone, and tall oil. The heat treatment was performed at the temperatures of 180°C and 212°C for three hours. The modified samples were analyzed using performance indicators and scanning electron microscope micrographs. The mechanical and physical properties were determined with water absorption, swelling, bending strength, and impact strength tests. All the modifiers penetrated better into sapwood than hardwood; however, there were significant differences in the impregnation behavior of the modifiers. As regards the effect of heat treatment, generally the moisture properties were improved and mechanical strengths impaired with increasing treatment temperature. In contrast to previous studies, the bending strength increased after melamine impregnation and mild heat treatment. It is concluded that the properties of impregnated wood can be enhanced by moderate heat treatment.     

Stand Density Control Diagrams for Scots pine and Austrian black pine plantations in Bulgaria

Stand Density Control Diagram (SDCD) is a stand-level mathematical model, which describes the relationships between yield, density and mortality throughout all stages of stand development. The SDCD is primarily used to derive density control schedules by management objectives. The main objectives of the present study are to define a modified model of SDCD for application to Scots pine (Pinus sylvestris L.) and Austrian black pine (Pinus nigra Arn.) plantations in Bulgaria, to examine the fitness of the model with representative experimental data sets from plantations of both species and to present a way of direct application of the SDCDs for practical purposes. The constructed SDCDs characterize the spatial-temporal dynamics of the pine plantations in a broad range of densities, forest sites and growth stages from 4 to 26 (28) m of dominant height class. The full density lines were fixed with self-thinning exponents α = 1.69 and α = 1.75 for Scots pine and Austrian black pine, respectively, and the trajectories of natural thinning for 23 initial densities (444-40000/ha) were determined. A direct way for application of the SDCDs to the plantation management was designed to estimate the optimal initial densities for the maximum attainable final yield and large-size wood production by self-thinning stands.     

Chemical emissions from adhesive-bonded wood products at elevated temperatures

Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was employed to examine the chemical emissions from the glued wood samples at elevated temperatures (150, 200, 250, 300, 350, 400, 450, and 500°C). Two wood species, Douglas-fir (Pseudotsuga menziesii) and southern pine (Pinus palustris), one structural adhesive, phenol–resorcinol–formaldehyde (PRF), PRF-bonded Douglas-fir, and PRF-bonded southern pine were evaluated. The volatile compounds with a mass range of 35–300 m/z emitted from the pyrolysis samples were separated by gas chromatography (GC) and identified by mass spectrometry (MS). The results indicated that compared to neat wood and resin film samples, several additional pyrolysis products were observed for the PRF-bonded wood samples including (1) acetaldehyde and butanedial for PRF-bonded Douglas-fir and (2) acetaldehyde, furfural, 2-furanmethanol, butanedial, 2,3-butanedione, cyclopropyl carbinol, 1,2-benzenediol, and 1-(acetyloxy)-2-propanone for PRF-bonded southern pine. These additional compounds were possibly associated with the interaction between wood and PRF resin. The results also indicated that bonded wood products would be less thermally stable than those of neat wood and PRF resin samples.