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     

Effect of post treatment temperature and humidity conditions on fixation performance of CCA-C treated red pine and southern pine

introductionWaterbornepreservativesareamajorcomponentofthewood-treatingindustrybecauseoftheireaseofapplication,lowcost,andthecleanappearanceofthewoodattertreatment.Theuseofchromatedcopperarsenate(CCA)preservativesintheUSAhasgrownfroma14%shareofthewoodpreservativesmarketin1977to73%in1987(Micklewright1993).ThisismainlyduetotheincreasinguseofCCAtreatedwoodasdecksandoutdoorstructures.ThewaterbornepreservativeCCAhasbecomeoneofthemosteffectivetreatmentsforNorthAmericanwoodproduCts,usedinapplic…     

Wood drying process: impact on Scots pine lumber durability

There are indications that the drying process may have negative effects on the natural durability of wood. The impact of various drying processes on the durability of Scots pine lumber has been evaluated with mass loss in a decay test with brown rot fungus, Coniophora puteana, as measure of the decay resistance of sapwood and inner and outer heartwood. Drying with or without steam conditioning was performed in six different series: air drying, kiln drying at temperature ranges commonly used in Swedish sawmills at 70°C and 90°C with two different regulation principles, and one high-temperature drying at 110°C. Durability varied considerably both between and within boards. Sapwood showed considerable less durability than heartwood. No difference in durability was found between inner heartwood and outer heartwood. Air-dried heartwood showed the highest durability compared to other drying series. The lowest durability in sapwood and heartwood was found for series dried at the 90°C temperature level with high material temperature early in drying. The interpretation is that the duration of high material temperature at high moisture content (MC) is the critical combination for decay resistance in heartwood. Steam conditioning after drying decreased durability in sapwood.     

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.     

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.     

Experimental determination and modeling of equilibrium moisture content from the sapwood of Mexican pine (<Emphasis Type="Italic">Pinus pseudostrobus</Emphasis> Lindl.)

A desorption isotherm is a very important basis in the understanding of drying process. In this study, the desorption isotherms from the sapwood of Mexican pine (Pinus pseudostrobus Lindl.) were determined by the gravimetric method (discontinuous control of sample weight) at 30℃ and 50℃. The salt method was used in the range of water activities from 0.11 to 0.89. The results show that the desorption ability of Mexican pine sapwood increased with temperature at a given relative humidity. The experimental data was further simulated with the models, i.e., BET, GAB, Oswin and Henderson models. The GAB, Oswin and Henderson models allow the representation of the entire desorption isotherms. The BET model showed a better fit for water activity lower than 0.35, with a mean relative deviation of 0.0286 at 30℃ and 0.0167 at 50℃. Simultaneously, the BET model gave a better representation of moisture content in the monolayer saturation region. Overall, the GAB model ensured the best simulation of the entire isotherm, while the Henderson model displayed the worst simulation.     

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.     

Canopy cover effects on cellulose decomposition in oak and pine stands

Cellulose mass loss was measured for four levels of canopy cover,i.e., clearcut, 25%, 75%, and uncut, in northern red oak (Quercus rubra) and red pine (Pinus resinosa) stands in northern Lower Michigan, USA. Cellulose mass loss was more rapid in the clearcut and 25% canopy cover treatments than in the 75% canopy cover and uncut treatments. After 4 month incubation of cellulose filter papers, mass loss rates averaged 75.2% in the clearcut, 56.3% in the 25% canopy cover, 46.9% in the 75% canopy cover, and 45.7% in the uncut stands. For the clearcut and the 25% canopy cover treatments, cellulose mass loss in the mineral soil layer was significantly higher than in the forest floor after 2 and 4 months of incubation, while cellulose mass loss of the uncut treatment was significantly lower in the soil layer than in the forest floor after 4 months of incubation. Cellulose mass loss was not significantly different between the oak and the pine stands (p > 0.05), but cellulose mass loss rates in other canopy cover treatments except for the clearcut were generally higher in red oak stands than in red pine stands. These results suggest that canopy manipulation increases cellulose decomposition and may stimulate nutrient cycling process in canopy removal stands. This study was supported in part by USDA Forest Service and Michigan Technological University.     

Modeling of simultaneous three-dimensional leaching and chemical reaction of CCA components in unfixed wood exposed to water

The leaching of chromated copper arsenate (CCA) components from unfixed wood immersed in water is modeled in three dimensions using an analytical model of simultaneous diffusion and reaction. Parameters for the model were determined by laboratory leaching experiments with small uncoated wood samples, departing from previous approaches where diffusion coefficients are measured in one dimension at a time. The diffusion coefficients and reaction rate constants of Cr⁶⁺, total Cr, Cu, and As in unfixed CCA-treated red pine (Pinus resinosa Ait.) and southern pine (Pinus sp.) were estimated, assuming first-order reaction rate equations and independent Fickian diffusion for all components. Estimated reaction rate constants and diffusion coefficients were not significantly affected by sample dimensions except for very severe longitudinal leaching from short samples. The predictive ability of the model using diffusion coefficients determined from immersion of small lab samples was evaluated by leaching experiments in a spray booth of southern pine lumber at 21 and 60°C, and red pine pole sections at 21°C. The predictive ability of the model was mixed, but in all cases represents a significant improvement over small-block leaching models which do not account for the diffusive nature of the leaching process.     

Decay resistance of sapwood and heartwood of untreated and thermally modified Scots pine and Norway spruce compared with some other wood species

Abstract

Thermal modification has been developed for an industrial method to increase the biological durability and dimensional stability of wood. In this study the effects of thermal modification on resistance against soft- and brown-rot fungi of sapwood and heartwood of Scots pine and Norway spruce were investigated using laboratory test methods. Natural durability against soft-rot microfungi was determined according to CEN/TS 15083-2 (2005) by measuring the mass loss and modulus of elasticity (MOE) loss after an incubation period of 32 weeks. An agar block test was used to determine the resistance to two brown-rot fungi using two exposure periods. In particular, the effect of the temperature of the thermal modification was studied, and the results were compared with results from untreated pine and spruce samples. The decay resistance of reference untreated wood species (Siberian larch, bangkirai, merbau and western red cedar) was also studied in the soft-rot test. On average, the soft-rot and brown-rot tests gave quite similar results. In general, the untreated heartwood of pine was more resistant to decay than the sapwood of pine and the sapwood and heartwood of spruce. Thermal modification increased the biological durability of all samples. The effect of thermal modification seemed to be most effective within pine heartwood. However, very high thermal modification temperature over 230°C was needed to reach resistance against decay comparable with the durability classes of “durable” or “very durable” in the soft-rot test. The brown-rot test gave slightly better durability classes than the soft-rot test. The most durable untreated wood species was merbau, the durability of which could be evaluated as equal to the durability class “moderately durable”.     

Development and applications of the relative spacing model for loblolly pine plantations

The development through time of relative spacing was modeled for loblolly pine (Pinus taeda L.) plantations across the Lower Coastal Plain (LCP) and Piedmont and Upper Coastal Plain (PUCP) regions of the southern United States, using data from two culture/density studies. The lower asymptotic limit of relative spacing decreases exponentially with increasing planting density in both the LCP and PUCP regions. It is also correlated with site index in the LCP region, but not in the PUCP region. In the PUCP region, loblolly pine plantations with the intensive management regime approach a higher value of minimum relative spacing than those with the operational management regime. In the LCP region, however, for a given planting density and site index loblolly pine plantations approach the same limit of relative spacing, regardless of management regime. Site index, planting density, and management intensity also affected other model parameters. How the resulting relative spacing models are used to determine thinning schedules and indirectly derive the survival patterns over time for young loblolly pine plantations were explored and outlined.     

Effect of conditioning on distribution and availability of alkaline copper quat (ACQ) preservative components in earlywood and latewood of southern pine

The interactions of alkaline copper quat (ACQ) components with the earlywood and latewood tissues of southern pine were investigated. There was a highly significant redistribution of the copper amine component from the earlywood to the latewood during post-treatment fixation at 50°C, which was mainly attributed to diffusion of copper amine from the earlywood into the latewood. A small amount of copper amine redistributed between the tissues and toward the wood surfaces during drying following fixation. The redistribution within the wood was similar whether the preservative penetrated longitudinally, tangentially, or radially into the wood during pressure treatment. This redistribution resulted in lower solubility of copper, and this effect contributes to the overall copper fixation in ACQ-treated wood. The quat component did not significantly diffuse after treatment, and its concentration remained much higher in the earlywood compared to the latewood.     

High-temperature drying of southern pine 2 by 4's: Effects on strength and load duration in bending

Summary Southern pine lumber specimens dried by conventional (82 °C maximum) and high temperature (116 °C for less than 1 day) schedules were tested to determine if high-temperature drying affects load duration. Results show that high-temperature drying has no appreciable effect on load duration, probably because it has no appreciable effect on static strength. Results from combining the data from both kinds of drying suggest that the load duration effect is less severe for lumber than for small clear specimens.     

Loblolly pine (Pinus taeda L.) essential oil yields affected by environmental and physiological changes

ABSTRACT

Loblolly pine (Pinus taeda L.) is one of the most abundant timber species in the United States and needles from this species contain essential oils (EOs) with antibacterial properties. Needles from trees of one loblolly pine clone were assayed for the EOs α-pinene, β-pinene, terpineol, limonene, and caryophyllene across a growing season. Results showed strong positive correlations among EOs, except for caryophyllene, with Pearson’s correlation values ranging from .66–.96. Simultaneously, physiological attributes of tree stomatal conductance, water stress, and environmental attributes including soil moisture, photosynthetic active radiation (PAR), temperature, wind speed, and relative humidity were measured. The plants modulated the EO concentrations as a function of a changing environment season. The collection month had the largest effect on EO yields and highest yields were during the beginning of the growing season. Decreases in EOs were evident as the growing season progressed and as plants exhibited greater water stress, temperatures, solar radiation, and less stomatal conductance and soil moisture. Loblolly pine’s main constituents of EOs were tightly linked and were influenced by seasonal changes (i.e., month); still, environmental/physiological attributes exhibited significant effects on α-pinene, β-pinene, and limonene concentrations. Early spring conditions with ample water were most conducive to high concentrations of EOs.     

Blue stain fungi associated withTomicus piniperda (Coleoptera: Scolytidae) on Japanese red pine

A number of various species of blue-stain fungi were isolated fromTomicus piniperda adults at various stages of development, as well as from the galleries, pupal chambers and sapwood underneath galleries on Japanese red pine. This study was an attempt to identify the species, composition of blue-stain fungi associated withT. piniperda, the frequency of occurrence of the fungi, and their role in the sapwood-staining of Japanese red pine in Tsukuba City, central Japan. Among the seven species of blue-stain fungi isolated, an undescribed species ofOphiostoma together withO. minus were the dominant species and closely associated withT. piniperda. These two species occurred on newly emerging adults more frequently than the overwintered adults.Hormonema dematioides was also associated with the beetle, however, its frequency of occurrence from the emerged new adults was very low. Although the two other species,O. ips andGraphium sp. were also isolated from emerged beetles, the frequency of these fungi from gallery systems suggested that they were accidentally carried byT. piniperda. Leptographium wingfieldii, known to be associated with the beetle in Europe, was also isolated at a very low frequency and the fungus seemed not to be closely associated with the beetle.Ophiostoma sp. andO. minus appear to be the most important causes of blue-stain of Japanese red pine sapwood after infestation byT. piniperda.     

日本黑松和赤松精英树半同胞家系生长及遗传参数分析

通过对泰山竹林寺景区引种27年生的日本黑松和赤松精英树半同胞家系生长特性和遗传参数的研究发现：（1）黑松生长量略优于赤松,它们的平均胸径分别为21．83cm和20．84cm,平均材积分别为0．264m^3和0．262m^3。从遗传特性上来看,黑松和赤松的胸径的家系h^2分别为0．7668和0．4404。（2）从家系间比较可知：黑松大岛6^#、黑松柳井3^#、当地黑松、黑松柳井2^#生长指标居于前4位,材积分别为0．4725m^3、0．3526m^3、0．3179m^3和0．3144m^3。赤松都浓3^#、赤松都浓2^#、赤松大岛1^#居于前列,材积分别为0．429m^3、0．343m^3和0．365m^3。     

Comparison of organic matter dynamics in soil between Japanese cedar (Cryptomeria japonica) forest and adjacent Japanese red pine (Pinus densiflora) forest established on flatland

In order to clarify the effects of tree species on organic matter dynamics in soil, we investigated the amount of forest floor material, leaf litter decomposition rate, soil chemical characteristics, soil respiration rate and cellulose decomposition rate in a Japanese cedar forest (cedar plot) and an adjacent Japanese red pine forest (pine plot) established on a flatland. The amount of forest floor material in the cedar plot was 34.5 Mg ha⁻¹ which was greater than that in the pine plot. Because the leaf litter decomposition rate was higher in the pine plot than in the cedar plot, it is likely that the difference in the amount of forest floor material between the plots is caused by the difference in the leaf litter decomposition rate. The C concentrations of soil in the cedar plot were 1.2–2.1 times higher than those in the pine plot. Soil pH(H₂O)s in the cedar plot were significantly higher than those in the pine plot. The soil respiration rates and the rates of mineralized C in the cedar plot byin vitro incubation were higher than those in the pine plot. From this result, it is assumed that soil organic matter in the cedar plot was decomposed relatively faster compared with the pine plot. Furthermore, microbial activities, which were reflected as cellulose decomposition rates in the cedar plot, were higher than those in the pine plot. A part of this paper was presented at the 109th Annual Meeting of the Japanese Forestry Society (1998).     

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.     

Effect of fungal exposure on the strength of thermally modified Norway spruce and Scots pine

Abstract

Thermal modification at elevated temperatures changes the chemical, biological and physical properties of wood. In this study, the effects of the level of thermal modification and the decay exposure (natural durability against soft-rot microfungi) on the modulus of elasticity (MOE) and modulus of rupture (MOR) of the sapwood and heartwood of Scots pine and Norway spruce were investigated with a static bending test using a central loading method in accordance with EN 408 (1995). The results were compared with four reference wood species: Siberian larch, bangkirai, merbau and western red cedar. In general, both the thermal modification and the decay exposure decreased the strength properties. On average, the higher the thermal modification temperature, the more MOE and MOR decreased with unexposed samples and increased with decayed samples, compared with the unmodified reference samples. The strength of bangkirai was least reduced in the group of the reference wood species. On average, untreated wood material will be stronger than thermally modified wood material until wood is exposed to decaying fungi. Thermal modification at high temperatures over 210°C very effectively prevents wood from decay; however, strength properties are then affected by thermal modification itself.