基于声发射技术的杨木蛀干害虫幼虫活动规律研究

采用搭建AE信号采集平台,8∶00-23∶00内1h监测1次(其中测定0.5h、休息0.5h)、循环监测采集数据,利用matlab软件、傅里叶变换法等处理信号、绘图噪声频谱图等方法,探索研究了基于声发射技术的蛀干害虫幼虫活动规律研究可行性和杨木蛀干害虫小蠹幼虫活动规律,结果为本研究建立的系统能实现对杨树幼虫声音信号的采集、分析和处理;杨树小蠹幼虫声音信号主频主要集中于64.0K^65.5KHz频段内;测量时间段内,杨树小蠹幼虫最活跃时间段在20∶00-21∶00。     

木包装携带钻蛀性害虫的概率场景分析初探

文章运用概率场景分析方法分析了木包装携带钻蛀性害虫定殖风险的主要过程,认为木包装携带有害生物定量化风险评价场景主要有2种,假设携带的钻蛀性害虫为X,场景分析认为其传播并在新的地区定殖主要经历6个关键环节,在对各个环节发生的概率进行分析的基础上,初步建立了计算风险概率的模型,同时,对各个环节的定量化方法进行了阐述,以期为进一步理解概率场景分析方法,为有害生物定量化风险评价提供借鉴。     

Genetic variation of extractives in the wood of trembling aspen

Summary Thirteen clones of Populus tremuloides (Michx.) from central Alberta, Canada, were sampled to determine variation patterns within and among clones for benzene-alcoholwater extractives. Significant differences among clones were present; however, the broadsense heritability for extractive content was low (0.13). Extractive content was highest near the pith and decreased outward. Genetic and phenotypic correlations between rate of growth (ring widths) and extractive content indicated that faster growing clones or trees tend to exhibit less benzene-alcohol-water extractives.The authors would like to thank the Forest Development Research Trust of the Alberta Department of Energy and Natural Resources, and Natural Science and Engineering Research Council of Canada (NSERC A 1281, NSERC-SPF 00291) for financial support     

The chemistry of decayed aspen wood and perspectives on its utilization

Summary The objectives of this research were to investigate the proportion of decayed wood in mature aspen stems, its chemical composition and its potential utility as a fuel or as a substrate for conversion to fine chemicals as part of an integrated utilization scheme. Three sound and ten decayed aspen stems were sampled from a boreal forest site. Stem analysis indicate that on average, 20% of the merchantable stem volume was in advanced decay and that considerable sound wood recovery was possible. Wood specific gravity and chemical composition were determined. The holocellulose content (volumetric basis) in advanced decayed wood was reduced by 67%. Thermal analysis of the wood using a differential scanning calorimeter provided graphical evidence of a different sequence of events occurring during the combustion of decayed wood and a resulting heat content per unit weight that was 40% higher than that of sound aspen wood. A higher degree of enzymatic hydrolysis was attainable with white-rotted aspen wood. Approximately 62% of the theoretical glucose yield was obtained from decayed aspen wood after alkali-peroxide pretreatment followed by a 12 hour hydrolysis using technical grade enzymes. The above information is used to elucidate future opportunities for wood recovery and energy production from decayed wood resources.The authors would like to thank the Ontario Ministry of Natural Resources, Kirkland Lake for their cooperation; and for the technical assistance by Sally Krigstin, John Leigh, Samir Konar, Ganesh Deka and Doug Charles. We would also like to thank Dr. Morris Wayman, University of Toronto, for his advice and inspiration. We are especially grateful to the following persons and companies for supplying us with enzymes and their associated technical literature: Mr. John Bayard of Van Waters & Rogers Ltee, Canada, representing NOVO Industri, Denmark; Mr. Ian Hodge representing the Miles Biotechnology Group, Canada; and Dr. Gunther Eckert, B.A.S.F., Germany for obtaining and forwarding the products and information of Rohm GmbH, Germany. This work has been partially funded by the Edward Johnson Fellowship, University of Toronto     

Modeling wood fiber deformation caused by vapor expansion during steam explosion of wood

Steam explosion is a process used to enhance enzyme penetration and digestibility of wood. Wood chips are processed with high-pressure steam for a limited time, and the bonding between polysaccharides and lignin is weakened. After this processing, the pressure is rapidly reduced to induce steam explosion where the vapor inside a fiber expands and exerts pressure on the fiber walls. This pressure causes fiber deformation and breakage. In this study, fiber deformation caused by vapor expansion was simulated by single wood fibers using finite element modeling. When pressure is applied inside a fiber, it is likely to break from the corner and midway between two adjacent corners. The fiber is modeled with four layers (P, S1, S2, and S3). Although the P, S1, and S3 layers are very thin, they significantly prevent fiber deformation. The fibers with a thin wall and a low micro-fibril angle (MFA) deform more than the fibers with a thick wall and a higher MFA. It was found that the shape of the fiber plays an important role in its deformation. The areas of localized strain are the most likely places for fiber splitting. Essentially, fiber wall damage is more likely to occur in (1) thin-walled fibers, i.e., earlywood, (2) fibers with damaged P and S1 layers, (3) fibers with low MFAs, and (4) fibers with irregular cross-sections. Different chemical pretreatments, fractionation procedures, and selections of raw materials can accordingly be considered to produce easily steam-exploded materials.     

Trapping wood boring beetles in Italian ports: a pilot study

Invasive alien species cost forestry billions of euros every year and their early detection is becoming of utmost importance. The aim of this study is to improve some of the techniques available for trapping alien wood boring beetles (Scolytinae, Cerambycidae, and Buprestidae) arriving at high-risk sites, such as ports. During 2009–2011, trapping carried out in four Italian seaports tested the comparative efficiency of different luring (single-lure vs. multi-lure traps) and trap designs (cross-vane vs. multi-funnel). In addition, trap captures within the ports were compared with those obtained in surrounding areas. Six out of 49 species trapped in 3 years of investigation were of alien origin: four Scolytinae and two Cerambycidae. The number of species trapped in multi-lure traps was as high as that resulting from the sum of the single-lure traps. The two trap designs performed equally well, but multi-funnel traps were more robust and easier to use in ports. In 2011, the number of species trapped in ports and surrounding areas was similar, although differently distributed. On a total of 26 species trapped in this experiment, nine were exclusive to ports, of which three aliens, eight were exclusive to surrounding areas, of which one alien, and nine were common to both habitats, of which one alien. In conclusion, we suggest the use of multi-funnel traps baited with different lures for monitoring alien wood boring beetles in ports. Using traps outside the port is also recommended to validate the surveillance program.     

High-yield pulping of aspen wood: Relation between pulp properties and fibre characteristics by multiple linear regression

Summary High-yield pulps have been obtained by means of steam explosion pulping. This process was carried out as follows: 1) chips soak impregnation (60 °C, 24 h, L/C = 6) in solutions containing 8% Na₂SO₃ and a variable concentration of either Na₂CO₃ or NaHCO₃, ranging from 0 to 2%; 2) cooking at high temperature (190–200 °C) for short time (2-1 min); 3) rapid pressure release. This work shows that mechanical properties were substantially improved when adding a second chemical to the Na₂SO₃ impregnation solution. Moreover, refining energy requirement was significantly reduced. However, the higher chemical charge used made the optical properties drop. In this paper, mathematical models have been proposed in order to accurately predict specific refining energy and paper properties from sulfonate content and pulp yield. In addition, the relative importance of these two parameters has been studied.Thanks are due to the Natural Science and Engineering Council of Canada (NSERC) and Fonds pour la Formation de chercheurs et l'aide à la recherche of Quebec (FCAR) for their financial support.     

The fiber saturation point of various morphological subdivisions of Douglas-fir and aspen wood

Summary In both Douglas-fir and aspen wood, the fiber saturation point of early wood is greater than that of late wood, solvent extraction lowers the fiber saturation point, and the fiber saturation point for reaction wood is less than that for whole wood.     

Surface checking of wood is increased by photodegradation caused by ultraviolet and visible light

The aim of this research was to test the hypothesis that exposure to solar radiation increases the checking of wood exposed to the weather, and to examine the causes and spectral dependency of such an effect. Lodgepole pine decking samples were exposed outdoors under filters, which blocked selected regions of the solar spectrum while allowing other weathering factors to act on samples. Surface checking in samples was quantified after 12, 24 and 36 weeks of exposure, and the chemical and micro-structural changes occurring at weathered wood surfaces were examined. Check numbers and dimensions were greater in samples exposed under a filter to the full solar spectrum than in samples exposed under filters that blocked the transmission of UV, visible or infrared radiation. Samples that were shielded from more energetic wavelengths developed less checking and also showed less delignification at the exposed wood surfaces. Checks developed at the margins of rays and propagated at the interface between adjacent tracheids, close to the middle lamella. We conclude that exposure to UV and visible light increases the tendency of wood to check during exterior exposure. Our findings point to a link between changes in cell micro-structure as a result of photodegradation of lignin and the development of visible checks in wood exposed outdoors.     

加工活性炭处理松材线虫病死木技术的研究

经３ａ的试验和实践结果表明，加工活性炭处理松材线虫病死木中松褐天牛成、幼虫等媒介昆虫是一项简单易行、灭害彻底、效益较高的处理松材线虫病死木的新技术，值得在疫区推广应用。     

Growth and frost hardening of European aspen and backcross hybrid aspen as influenced by water and nitrogen

• Introduction  

The interactive effects of water and nitrogen (N) on frost hardiness are not well known in broad-leaved trees. Furthermore, new environmental conditions may favour naturally generated hybrids between native and introduced tree species over native species.     

A high-throughput X-ray-based method for measurements of relative wood density from unprepared increment cores from Picea abies

We have described a high-throughput method for ring width and relative wood density analysis of unprepared increment cores based on conventional computer tomography scanners (CT scanners) used in health care. The method was developed for analysis of 5-mm increment cores collected in forest genetic and tree breeding trials. For these studies, the relative differences between individuals are more important than the exact value. The method is highly efficient in terms of quantitative data collection from large number of samples. There are, however, limitations in terms of resolution and accuracy on very small volumes of wood that must be considered when using the method to measure individual growth rings or increment cores thinner than 5 mm. However, in studies comprising large number of samples, the use of cost-efficient CT scanning on the major part of the material, combined with more laborious high-resolution scanning on sub-samples can be a good combination for efficient determination of radial variation in growth rate and wood density.     

Fracture energy approach for the identification of changes in the wood caused by the drying processes

Specific fracture energy measurements were applied to identify changes caused by wood-drying processes of solid wood. Specimen design and geometry as well as parameters and specifications for a fracture energy test were determined experimentally. The specific test set-up was applied on plantation teakwood sample sets of standard as well as alternating convection kiln dryings and one oven drying. The results show that alternating changes of the drying temperature along with the equilibrium moisture content (EMC) in a kiln schedule have a small but significant decreasing effect on the specific fracture energy in the radial/longitudinal as well as the tangential/longitudinal testing direction. Furthermore, oven drying at constant high drying temperature along with low EMC did not result in a significant change of specific fracture energy compared with standard drying, but caused greater scattering values in both transverse crack propagation systems.     

Dynamic simulation of disintegration of wood chips caused by impact and collisions during the steam explosion pretreatment

Steam explosion (SE) pretreatment produces damaged and disintegrated biomass with a large surface area which facilitates enzymatic hydrolysis for the production of biofuels and other value-added chemicals. It was observed during experiments that wood chips disintegrate into smaller pieces because of collisions and impact with each other and the walls of the SE equipment. In this study, these events were simulated using the finite element method. Wood chips were simulated in this model as a linear elastic material until failure. The damage initiation was identified using Hashin’s damage initiation criteria. Once the damage was initiated, additional loading caused the evolution of damage, i.e. degradation and breakage of the material, which was modelled using the material property degradation model and deletion of the failed elements. Elastic and strength properties of spruce wood were estimated at ambient conditions (12 % moisture content at 20 °C) and at SE conditions (30 % moisture content at 160 °C). Comparison of simulations performed using material properties at ambient and SE conditions revealed that the damage in wood chips significantly increased because of the steam treatment. The effects of wood chip velocity and orientation at the time of impact were studied as well. It was found that wood chips moving at high velocity and impacting with the steel wall in the radial direction acquire the most damage.     

注干法防治林木害虫技术

近年来 ,杨树已成为我省造林绿化的主栽树种之一 ,约占整个造林面积的 80 %以上。因此杨树林相单纯 ,树种单一 ,给杨树病虫害的生息和传播创造了极为有利的环境条件。再加上杨树属高大乔木 ,高达 2 0～ 30ｍ ,弥雾机喷雾防治难以达到如此高度 ,即使用工农 36喷雾 ,也很难达到如此防治高度 ,而且防治不方便 ,不彻底 ,费用大 ,严重影响防治效果 ,同时对周围生态环境破坏严重。面对该情况 ,沛县森防站为确保造林绿化成果 ,引进了徐州市森防站与南京林业大学开发成功的重大科研项目成果——— 6ＨＺ系列树木注药机。1　注干机防治林木害虫技术原…     

Production and investment evaluation of oyster mushroom cultivation on the waste dendromass: a case study on aspen wood in Slovakia

This paper addresses the processes and investment evaluation of utilizing available dendromass in an easy and close-to-nature way under Central European conditions in Slovakia. Wood of the European aspen (Populus tremula L.) that has generally been considered of little economic value was efficiently used as a growth medium for the oyster mushroom (Pleurotus ostreatus (Jacq.) P. Kumm.). The production of the fruiting bodies of this mushroom were evaluated for 5 years under natural forest conditions. The evaluation focused solely on aspen wood, specifically, the most valuable part – the trunk. The investment assessment revealed the high economic value of the fruiting bodies of the oyster mushroom inoculated into aspen wood blocks for the period of five years. In particular, the results of the net present value (NPV?=?347.78 €/m³) as well as the profitability index (PI?=?1.63) and discounted payback period (DPP ≈ 2 years and 8 months) point to the high profitability of such a project under the given conditions. The results could be helpful and inspiring for forest and garden owners when deciding how to utilize low-value waste dendromass, low-quality aspen wood and other tree species in small-scale forest management.     

Retention of aspen (Populus tremulae) at final cuttings - The effect of dead wood characteristics on saproxylic beetles

To preserve biodiversity in managed forest landscapes dead and living trees are retained at final cuttings. In the present study we evaluated the effect of these practices for saproxylic (wood-dependent) beetles inhabiting dead aspen trees (Populus tremulae). For saproxylic beetles, tree retention at final cuttings can be expected to be especially valuable for species adapted to sun-exposed dead wood, a substrate that only rarely occurs in well managed forest stands. Therefore, the current evaluation was conducted as a comparison of species richness, species density (number of species per sample), assemblage composition and occurrence of individual species between clear-cuts, where aspen trees were retained, and closed forest stands with aspen trees. The study was conducted in central Sweden and the beetles were sampled by sieving of bark from CWD (coarse woody debris) of aspen. There was no significant difference in rarefied species richness between forest and clear-cut sites. Species composition differed significantly between the two stand types. Generalized linear mixed-effects models predicted the species density to be 34% lower in CWD objects in forest sites than on clear-cuts. This pattern could partly be explained by differences in CWD diameter, decay class and bark types between the two stand types (clear-cut/forest). Stand type was a significant predictor of occurrence in individual CWD objects for 30% of analysed individual beetle species. For all species except one, the variable stand type predicted higher occurrence on clear-cuts than in forest stands. To conclude, our results demonstrate that retention of aspen on clear-cuts contributes to population recruitment of a different assemblage of species than CWD within stands.     

Effect of oil impregnation on water repellency,dimensional stability and mold susceptibility of thermally modified European aspen and downy birch wood

Conventional chemical wood preservatives have been banned or restricted in some applications due to human and animal toxicity and their adverse impact on the surrounding environment. New, low-environmental-impact wood treatments that still provide effective protection systems are needed to protect wood. Thermal modification of wood could reduce hygroscopicity, improve dimensional stability and enhance resistance to mold attack. The aim of this study was to investigate if these properties enhanced in thermally modified (TM) wood through treatments with oils. In this study, TM European aspen (Populus tremula) and downy birch (Betula pubescens) wood were impregnated with three different types of oil: water-miscible commercial Elit Träskydd (Beckers oil with propiconazole and 3-iodo-2-propynyl butylcarbamate, IPBC), a pine tar formulation and 100% tung oil. The properties of oil-impregnated wood investigated were water repellency, dimensional stability and mold susceptibility. The treated wood, especially with pine tar and tung oil, showed an increase in water repellency and dimensional stability. However, Beckers oil which contains biocides like propiconazole and IPBC showed better protection against mold compared with pine tar and tung oil. To enhance the dimensional stability of the wood, pine tar and tung oil can be used, but these oil treatments did not significantly improve mold resistance rather sometimes enhanced the mold growth, whereas a significant anti-mold effect was observed on Beckers oil treated samples.     

Indentation of wood by wedges

Summary The deformation processes involved in wedge indentation of wood are described. The behaviour of wood is compared to that of an elastic-plastic solid and that of a cellular body. It approximates towards the former when its density is high and towards the latter when its density is low. The hardness of wood is examined as a function of density and of wedge angle.We wish to thank the University Grants Committee and the New Zealand Forest Service for supporting this work