Hardwood timber is becoming increasingly important in Europe for its use as structural material, both as solid wood and engineered structural products. In Italy, the great abundance of beech forests has recently led to a research project to investigate the use of this species in construction. A first step is the characterization of the raw material for the production of structural glued products. This requires developing the strength grading of beech boards, both by visual and machine methods. To the aim, four provenances were collected across the distribution of beech in Italy. The main strength reducing characteristics were measured visually, and the dynamic modulus of elasticity was determined before performing the destructive bending tests of sampled boards. Correlation between properties were similar to what is usually observed for softwoods with the exception of density, which did not correlate with any other property. Several visual rules and machine settings were developed and compared, showing the effectiveness of both methods for the strength grading of beech. The grading yields for the high strength classes were very similar for machine and visual grading, while the machine permitted to reduce the number of rejected elements when two grades were selected at the same time.
& Key message Mechanized cutting may result in higher stump damage levels, especially if cutting is performed with shears. Nevertheless, stumps cut with mechanized technology do not show higher mortality rates than do stumps cut manually with a chainsaw. One-year growth is also unaffected, and so is nutrient balance within the stump. & Context Coppice harvesting must be mechanized in order to modernize coppice management, so that it can grow along with the dynamic new bio-economy. However, foresters are concerned that mechanized cutting may result in higher stump damage levels, which may cause increased mortality and lower growth rates. & Aims The goal of the study was to compare manual and mechanized cutting in terms of cut quality, stump damage levels, stump mortality, re-sprouting vigor, and shoot growth. & Methods The study was conducted in a classic Mediterranean coppice stand located in central Italy. The oak-dominated coppice was cut using a chainsaw (control), a disk saw and a shear. The experiment adopted a split-plot design, based on 5 plots divided into 15 subplots (1 subplot per plot and technology). Overall, 344 stumps were selected, tagged, and monitored over the first growing season after cutting. Stump size, cutting height, and cutting damage were determined right after cutting. At the end of the first growing season, the following parameters were also recorded: no. of shoots; height, diameter, and type of the tallest five shoots. Samples were collected from randomly selected stumps during the main phenological phases in order to determine the content of C, N, starch, and soluble sugar, as well as the C/N ratio. & Results Mortality ranged from 4 to 8%. Re-sprouting was generally vigorous, with dominant shoots often exceeding the height of 1.5 m after 1 year. Cutting technology had a significant effect on cutting height and cutting damage, but it had no effect on mortality, re-sprouting vigor, and nutrient balance within the stumps, at least in the first growing season. Resprouting vigor depended mainly on species. & Conclusion While it may result in higher stump damage levels, mechanized cutting does not seem to have any effects on coppice regeneration and growth, at least in the first year. Previous studies indicate that effects recorded during the first growing season may be representative of longer-term trends. The experiment will be continued to obtain additional confirmation.
The study assessed the postural risk of mechanised firewood processing with eight machines, representing the main technology solutions available on the market. Assessment was conducted with the Ovako Working posture Analysis System (OWAS) on 1000 still frames randomly extracted from videotaped work samples. The postural risk associated with firewood processing was variable and associated with technology type. Simple, manually operated new machines incurred a higher postural risk compared with semi- or fully automatic machines. In contrast, new semi-automatic and automatic machines were generally free from postural risk. In all cases, attention should be paid to postural risk that may occur during blockage resolution. The study did not cover the postural risk of firewood processing sites as a whole. The study provided useful information for selecting firewood processing machinery and for improving firewood machinery design, as part of a more articulate strategy aimed at enhancing the safety of firewood processing work sites. Practitioner Summary: The postural risk associated with mechanised firewood processing (eg cutting and splitting) depends on the type of equipment. Postural risk is highest (OWAS Action Category 2) with new in-line machines, designed for operation by a single worker. Fully automatic machines present minimum postural risk, except during blockage resolution.
The study sampled six representative work sites in Northern and Central Italy, in order to assess the risk for developing musculo-skeletal disease due to poor work posture (postural risk) among the operators engaged in semi-mechanized post debarking operations. Assessment was conducted with the Ovako Working posture Analysis System (OWAS) on 1200 still frames randomly extracted from videotaped work samples. The postural risk associated with post debarking was relatively low, and varied with individual operations based on their specific set up. Postural risk was higher for the loading station compared with the unloading station, which makes a strong argument for job rotation. The study suggested that the infeed chute of small-scale debarkers might be too basic and should be further developed, in order to reduce postural risk. Obviously, better machine design should be part of an articulate strategy aimed at decreasing the postural risk and based on proper worksite organization and specific worker training.
The interest in the use of beech wood in construction is growing steadily. Considering its high mechanical performance, it has a large potential for the production of glued timber structural products. However, the issue of structural bonding remains the one to be solved for an effective production and a safe use. Three adhesives (one-component polyurethane -PUR, PUR + primer and melamine-urea-formaldehyde -MUF) and two press systems (hydraulic and vacuum press) were investigated in the production of pure beech and combined beech-spruce-beech cross laminated timber (CLT). The evaluation of the bonding quality was performed with both standardized and optimized (the specimen layers were oriented with the wood grain forming an angle of 45° in respect to the load application) delamination and shear test methods. None of the adhesive tested met the requirements for delamination tests provided by the current standardization for softwood. As for the adhesive, PUR was that with the poorest performance in the production of the CLT panels entirely made of beech; the addition of a primer improved the bonding, permitting to achieve results comparable to those observed for MUF. On the contrary, in the production of beech-spruce panels, the three adhesive gave similar outcomes. The press system was not a relevant factor in terms of bonding quality. As for the testing methods, a size effect was noticed in the delamination test: the larger the specimen and the greater the delaminations observed. The shear tests on dry specimens were little sensitive, even if a 45° grain orientation seemed to reduce the rolling shear during shear test and to better highlight the effect of the bonding parameters. Combining delamination pretreatment and shear made the test more sensitive and subjective.
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