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.     

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…     

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.     

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.     

Regeneration of Rocky Mountain bristlecone pine (Pinus aristata) and limber pine (Pinus flexilis) three decades after stand-replacing fires

Rocky Mountain bristlecone pine (Pinus aristata) and limber pine (Pinus flexilis) are important high-elevation pines of the southern Rockies that are forecast to decline due to the recent spread of white pine blister rust (Cronartium ribicola) into this region. Proactive management strategies to promote the evolution of rust resistance and maintain ecosystem function require an improved understanding of the role of disturbance on the population dynamics of both species and environmental conditions that favor seedling establishment. We examined patterns of bristlecone and limber pine regeneration across the perimeters of three, 29-year-old, high-severity burns in northern, central, and southern Colorado: Ouzel, Badger Mountain, and Maes Creek, respectively. Both species exhibited a very protracted regeneration response to these fires. Bristlecone pine regeneration was concentrated near burn edges and beneath surviving seed sources. This spatial pattern is consistent with limitations incurred by wind-dispersal, also borne out by the low occurrence of seedling clusters. Relative to unburned stands, the absolute abundance of bristlecone pine generally increased only on plots retaining some surviving trees. Limber pine regeneration pattern varied between sites: high in the burn interior at Ouzel, concentrated at burn edges at Badger, and mostly in unburned stands at Maes. Clark’s Nutcracker dispersal of limber pine in each study area was indicated by high seedling distance from possible seed sources and high frequencies of clustered stems. Except at Ouzel, the absolute abundance of limber pine decreased in burns. Across sites, establishment by both species was boosted by nearby nurse objects (rocks, fallen logs, and standing tree trunks), a relationship that extended out at least as far as the closest three such objects, usually found within 50 cm. Fire decreased the frequency of Pedicularis but increased Castilleja and Ribes species (alternate hosts of white pine blister rust), though only one species, R. cereum, was positively associated with either pine species. We conclude that regeneration of bristlecone and limber pine may benefit from natural disturbance or proactive management creating appropriately sized openings and microtopographic structure (e.g., abundant fallen logs); however, beneficial responses may require many decades to be achieved.     

Thermal treatment of electrical poles

Thermal treatment is used to preserve the wood without any addition of any toxic chemicals. This process increases the dimensional stability and darkens the color of the wood. The improvement of the resistance to decay of wood by thermal treatment is also often suggested in the literature. However, some latest works contested if the durability of heat-treated wood is improved when it is used in contact with ground. The objective of this study was to investigate the possibility of thermally treating electrical poles which are larger compared to the standard wood lumber. One of the applications for thermally treated wood poles could be their use in environmental sensitive areas (along rivers, for example) as a replacement for untreated western red cedar (WRC) poles which are more expensive. Green and pre-dried red pine (Pinus resinosa) and jack pine (Pinus banksiana) poles, both with circular and square cross-sections, were heated to high temperatures under humid and inert atmosphere. Operating parameters such as maximum treatment temperature, maintenance time at this temperature, heating rate and gas humidity were varied in order to find most suitable treatment conditions for the poles. The tests showed that most of the cracks are formed during the drying process while thermal treatment only widened already existing cracks. The circular shape seems to promote crack formation during the drying period since the directional dependence of shrinking creates more stresses in circular poles compared to the square poles. A slight decrease in flexibility of the wood with increasing temperatures was observed. The protecting effect of gas humidity against oxidation of wood and the importance of the application of a moderate heating rate for poles with large cross-sections are also demonstrated in this article. The impact of the heat treatment on the resistance to decay of electrical wood pole will be presented in a future publication.     

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.     

辐射松与杉木在高温干燥中萜烯类释放浓度研究

以40 mm厚的辐射松(Pinus radiata)和人工林杉木(Cunninghamia lanceolat)锯材为对象,研究高温干燥过程中干燥温度和锯材含水率对萜烯类产物释放浓度的影响,并与辐射松常规干燥中的萜烯类释放浓度作比较。高温和常规干燥过程中采抽气样次数均为5次,抽气速度为1.0 L/min,采样时间为30 min,采用Tenax管收集干燥过程中萜烯类产物,用气相色谱仪分析其成分及浓度。结果表明:高温干燥辐射松萜烯类释放浓度高于常规干燥辐射松与高温干燥人工林杉木,但萜烯类挥发物的组分有所差别。常规干燥辐射松锯材萜烯类释放浓度对环境是安全的,然而在高温干燥过程中,尤其在干燥中后期,当萜烯类挥发物浓度大于1.5 mg/m3时,对辐射松和人工林杉木释放萜烯类挥发物应采取回收措施,以确保对环境的安全。     

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.     

马尾松木材材性特点及加工利用研究

马尾松是我国松属树种中地理分布最广的一种,也是南方的造林先锋树种和主要用材树种。文中从物理力学性能、纤维特性以及渗透性等方面论述了马尾松木材材性特点,介绍了马尾松木材干燥及脱脂处理技术、木材蓝变及其防治方法,总结了马尾松木材在实木利用、人造板生产等领域的应用现状,展望了马尾松木材加工利用的发展前景。     

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.     

Photosynthetic acclimation of shade-grown red pine (Pinus resinosa Ait.) seedlings to a high light environment

Photosynthetic light acclimation in red pine (Pinus resinosa Ait.) seedlings was examined in a greenhouse study to better understand the physiological response of this species to increased light intensity following release from competition. Seedlings grown in a high (HL), medium (ML) or low (LL) light environment for 12 weeks were transferred to high light. Gas exchange and chlorophyll fluorescence of ML and LL seedlings were measured prior to and following transfer and compared with the HL control treatment. Photosynthetic characteristics were related to initial light treatment and time after transfer. Acclimation of gas exchange features to high light in shade formed ML and LL foliage was relatively rapid, with similar values among light treatments within 57 days of transfer. Acclimation of net photosynthetic rate was similar in ML and LL seedlings, and was associated primarily with increased mesophyll conductance to CO₂. The ratio of variable to maximal chlorophyll fluorescence (F_v/F_m) decreased initially after transfer, especially in LL seedlings, but recovered to normal values after 57 days. Red pine seedlings appear to be well adapted for photosynthetic acclimation to high light intensity, consistent with that reported for other early successional tree species.     

INFLUENCE OF FIRE ON KOREAN PINE AND SCOTS PINE TREES IN PLANTATION

The plantations of korean pine(Pinus koraensis)and scots pine(Pinus sylvesrisvar.mongolica)are mainly pure stands.Fires are gradually causing problems in theseplantations and being paid much more attention recently.Study on the influence of fire ontrees and the adaptation to fire,therefore,is of great important to probe the fire ecologicalproperties and the protection ways of these two species.The results are as follows:Bothof the species are easily damaged by fire,but korean pine is more susceptible.In the samefire,korean pine is damaged more seriously than scots pine although they have the samesize.Young individuals have low fire resistant capacity and can be damaged seriously,andolder ones have strong fire resistance and can be damaged lightly.Up-hill fire makes aserious damage to the trees distributed in up-slopes with the reason of higher fireintensity.Down-hill fire makes a serious damage to the trees distributed in down-slopcswith the reason of higher fire severity.The larger deocambium area in t     

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.     

Influence of fire and mountain pine beetle on the dynamics of lodgepole pine stands in British Columbia,Canada

An outbreak of the mountain pine beetle (Dendroctonus ponderosae Hopkins; MPB), currently affecting over 10.1 million hectares of lodgepole pine forests (Pinus contorta Dougl.) in British Columbia, Canada, is the largest in recorded history. We examined the dynamics of even-aged lodgepole pine forests in southern British Columbia, which were undergoing this MPB outbreak. Using dendroecology and forest measurements we reconstructed the stand processes of stand initiation, stand disturbances, tree mortality, and regeneration, and explained the current stand structure and the potential MPB impacts in selected stands. Our results indicate that stand-replacing fires initiated even-aged seral lodgepole pine stands in this region. In the absence of fire in the 20th century, multiple MPB disturbances, which each resulted in partial canopy removal, modified the simple one-layer structure of the fire-origin stands by the initiation of post-MPB disturbance regeneration layers, transforming the stands into complex, multi-aged stands. Despite high overstory mortality due to the current MPB outbreak, regeneration layers, which are likely to survive the current outbreak, will provide important ecological legacies and will contribute to mid-term timber supply.     

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。     

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”.     

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.