Wood density of three oak species in Tennessee, 1940–45 and 1970–75

Three oak species from East Tennessee were core-sampled to determine whether the density of wood produced in a pre-pollution period (1940–45) was different from that of a pollution period (1970–75) using gamma-densitometry. Component densities of average earlywood, average latewood, minimum earlywood, maximum latewood and average periodic density for Quercus alba L. and Quercus prinus L. were significantly greater for 1940–45 than for 1970–75. Differences between the two time periods for mean earlywood (P = 0.05), maximum latewood and mean periodic densities were found for Q. velutina.     

Manufacture and properties of Miscanthus–wood particle composite boards

Miscanthus sacchariflorus straw was used as a raw material for the manufacture of Miscanthus–wood particle composite board with Douglas-fir particles in ratios of 100/0, 80/20, 60/40, 40/60, 20/80, and 0/100. A commercial phenol–formaldehyde resin was used as a binder at 9 and 11 % for target densities of 0.50 and 0.65 g/cm³, respectively. The effects of the Miscanthus/wood particle ratio on the composite board properties were investigated. In addition, the density profile was also examined to improve the understanding of the composite board manufacturing process. Results indicate that the internal bonding value increased drastically in the board containing up to 50 % wood particles, providing a valuable parameter for subsequent research. The board properties were greatly improved with increasing density and binder addition level.     

Laboratory and exterior decay of wood–plastic composite boards: voids analysis and computed tomography

After exposure in the field and laboratory soil block culture testing, the void content of wood–plastic composite (WPC) decking boards was compared to unexposed samples. A void volume analysis was conducted based on calculations of sample density and from micro-computed tomography (microCT) data. It was found that reference WPC contains voids of different sizes from the micrometer range up to several cubic millimeters. Large voids were unevenly distributed within the composite sample. Void size and volume increased after conditioning the WPC in water at 70°C. Depending on the effect of exposure conditions, fungal decay during laboratory soil block testing increased the size and volume of voids. For laboratory samples, the calculated void volume was much higher compared to microCT-detected voids because of the limited resolution of the instrument on relatively large samples with many nano- and microvoids present in the material. In both laboratory and field samples, the creation of the voids resulted in a significant decrease in composite density. Decay damage observed as an increase in the size and volume of voids was particularly severe for boards exposed in the field. The calculated void volume in such samples was in reasonable agreement with voids detected by microCT.     

News and Views from SNS–Nordic Forest Research Co-operation Committee

Thirty-five research organisations are joining forces to develop methods for assessing the sustainability of the forestry-wood chain in Europe. The European Commission has set aside 13 million Euro (of a total budget of 19m Euro) for the project, dubbed eforwood, involving 18 of the European countries. Negotiations with the Commission are not yet complete, but the project will probably start by November this year, says Kaj Rosén, vice president of the Forestry Research Institute of Sweden (Skogforsk) and coordinator of the project.     

Forest characteristics and their variation along the lakeshore–upland ecotone

Abstract

In forestry operations riparian buffer zones have been retained mainly to protect water quality. Because riparian forests are also important for maintaining terrestrial biodiversity, the associated ecotones need to be characterized and defined. Forest characteristics were studied along 50 m lakeshore–upland gradients in semi-natural forests in boreonemoral Sweden. Significant changes in the density of living and dead trees, as well as in their diameters, were recorded. The edge influence was generally discernible 10–30 m from the shoreline and was manifested in the very high density of understorey and midcanopy trees. The species-specific responses reflected the known shade and flooding tolerances of tree species. Most dead trees were standing, or broken from the roots or tree base; relatively few uprooted trees were recorded, suggesting that wind is only a moderate mortality factor. In comparison with the literature, the studied lakeshore forests are distinct from managed and set-aside upland forests in terms of tree species composition and woody debris characteristics; they thus contribute to landscape heterogeneity. If buffer zones along lakes were designed so that they captured the entire riparian ecotone, this would increase their contribution to the conservation of terrestrial biodiversity.     

Characteristic fragment ions from lignin and polysaccharides in ToF–SIMS

Different model compounds for lignin, hemicelluloses and pectins were studied by time-of-flight secondary-ion mass spectrometry (ToF–SIMS). Mass spectra of Klason lignin from normal and compression spruce wood, aspen wood and wheat straw were compared. Spectra of brominated spruce and aspen wood sections showed fragment ions attributed to brominated guaiacyl and syringyl units in lignin at m/z 215, 217, 229 and 231, and m/z 245, 247, 249 and 261, respectively. Spectra of mono-, oligo- and polysaccharides showed fragment ions at m/z 127 and 145 characteristic for hexose units, and ions at m/z 115 and 133 characteristic for pentose units. The same ions were detected in spectra of delignified spruce and aspen wood sections. Labelling of anionic groups by Sr²⁺ ions followed by ToF–SIMS analysis showed that pectins were present at specific locations on the surfaces of spruce and aspen wood sections still after delignification with hydrogen peroxide in acetic acid.     

Investigation of dietary important components in selected red fleshed apples by GC–MS and LC–MS

Three red-fleshed apple cultivars (Malus ‘Geneva’: GFV-03, Hungarian hybrid: GFV-04, Malus pumila Niedwetzkyana: GFV-05) were investigated for their chemical composition by sHS–SPME–GC–MS and HPLC–DAD–MS/MS analytical techniques.     

Tree Seed Procurement–Diffusion Pathways in Wonogiri and Ponorogo, Java

Forty-two percent of the land area in the neighbouring districts (kapubatens) of Wonogiri, Central Java and Ponorogo in East Java is covered with secondary forests of naturalized exotic tree species that are common components of governmental land rehabilitation programs. The seed suppliers operating in the Wonogiri–Ponorogo area represent only 9% of the suppliers in Indonesia yet they account for 80–90% of the national tree seed supply capacity. Wonogiri–Ponorogo suppliers procure and sell 1,510 tons of seed annually. About 24% of this (362 tons) is exchanged between suppliers, 1,148 tons are sold to customers across Indonesia, and less than 1 ton is exported. About 72% of the seed sold (826 tons) is collected in the Wonogiri–Ponorogo area, the remainder originating in Sumatra, Madura and Nusa Tenggara. In Wonogiri–Ponorogo, tree seeds are collected by farmers on contract with seed assemblers or seed companies. Assemblers link farmer collectors with seed companies and middlemen, who sell seed to customers. Government agencies purchase 75% of the seed. Cover crop species, Gmelina arborea, Tectona grandis and Leucaena leucocephala account for the 85% of the total seed sold. The sheer volume of seed collected in Wonogiri–Ponorogo assures that it comes from a large number of unrelated trees over widely dispersed locations. However, research results indicate individual farmers collect seed from a limited number of adjacent trees. Experience indicates simple seed collection guidelines help farmers improve their seed collection practices and the genetic quality of seed collected. A commitment to seed quality by all agents involved in the seed trade and customers is required to make such guidelines functional and acceptable. Seed procurement and diffusion generate significant income for all seed agents. As the dominant agents who facilitate most of the activities and inputs required to move seed through the pathway from forests to customers, seed companies receive the most financial benefits. Farmer seed collectors are the most numerous agents in the seed pathway, with an estimated 22,500 farmers involved in seed collection activities annually. Farmer families living near seed companies earn additional income by processing seed.     

Excerpts from: Physiological and Medical Aspects of the Himalayan Scientific and Mountaineering Expedition, 1960–61

Please refer to Br Med J, September 8, 1962, pp 621–627 for a copy of this article.     

Comparison of water absorption and mechanical properties of wood–plastic composites made from polypropylene and polylactic acid

Abstract

This study focuses on the water absorption and mechanical properties of composites made from softwood sawdust and plastics, such as virgin and recycled polypropylene and polylactic acid (PLA). The composites were processed by extrusion, and their properties were investigated by a water immersion test, mechanical tests and a cyclic test for moisture resistance. Scanning electron microscopy was used to study the morphology of the fracture surfaces of the composites. The composites made with recycled polypropylene had the lowest water absorption and thickness swelling of the studied composites. The PLA composites made with heat-treated sawdust showed the highest flexural strength. Of the polypropylene based composites, virgin polypropylene resulted in composites with higher flexural strength. The Charpy impact strength of the composites was found to have an inverse trend compared to flexural strength. Cyclic treatment of the studied composites resulted in 20–60% loss of flexural strength, depending on type of composite.     

Nonindustrial private landowners,fires, and the wildland–urban interface

We estimate the value to a non-industrial forest landowner of information about the magnitude of fire arrival rates. A simulation based on a model from Amacher et al. [Amacher, G., Malik, A., Haight, R., in press. Not getting burned: the importance of fire prevention in forest management. Land Economics] is used to assess the cost of mistakes made by a landowner when stand management decisions are made without perfect knowledge of the fire arrival probability. These costs are reflected in the higher losses incurred by a landowner if fire arrives during a rotation. The representative landowner studied in the simulation is assumed to value nontimber benefits, and to make rotation age, planting density and fuel reduction decisions. We find that the value of information about the overall magnitude of fire risk is more than twice as high when the landowner underestimates fire risk, rather than overestimating it.     

Laboratory and environmental decay of wood–plastic composite boards: flexural properties

The flexural properties of wood–plastic composite (WPC) deck boards exposed to 9.5 years of environmental decay in Hilo, Hawaii, were compared to samples exposed to moisture and decay fungi for 12 weeks in the laboratory, to establish a correlation between sample flexural properties and calculated void volume. Specimens were tested for flexural strength and modulus, both wet and dry, at 23°C and 52°C. Some specimens degenerated to only 15% of original flexural strength. UV radiation had no impact on flexural properties of field-exposed boards; loss occurred mainly on the side opposite to the sun-exposed surface. The mechanism of the aging process on colonization of WPC by fungi was examined and is consistent with development of slow crack growth in the polyethylene matrix combined with wood decay by fungi. Wood particle decay, moisture, and elevated temperature were the major factors causing composite degradation, indicated by accumulation of voids and a severe decrease in flexural properties. To simulate long-term field impact (including decay) on WPC flexural properties in the laboratory, conditioning of specimens in hot water for an extended period of time is required. Exposure to water (70°C/5 days) was adequate for simulating long-term composite exposure in Hawaii of 4?×?15?×?86 mm³ specimens.     

Colorimetric and vibrational spectroscopic characterization of weathered surfaces of wood and rigid polyvinyl chloride–wood flour composite lumber

Rigid polyvinyl chloride–wood flour composite lumber containing either pine or maple wood flour and pine and maple lumber was subjected to accelerated weathering according to the ASTM Standard G 53 protocol. Non-weathered and weathered surfaces of all specimens were analyzed using colorimetric methods, reflectance infrared Fourier transform and Raman spectroscopic techniques. In the FT-IR spectra, conjugated ketones (1,744 cm^?1) of lignin as evidenced by their skeletal vibrations (1,560–1,500 cm^?1) and stretching (1,440–1,500 cm^?1) were reduced in weathered specimens. Cellulose was largely unaffected by weathering. C–O bending vibrations at 1,040 cm^?1 from holocellulose in pine specimens and intensity bands at 1,125–1,090 and 1,360 cm^?1 (C–O stretching and O–H bending from cellulose) in the maple and wood–plastic composite (WPC)-maple specimens were unaffected. A band at 1,650 cm^?1 became prominent after weathering of both pine and maple WPC specimens which is due to C=C–C=C stretching vibration of weathered PVC portion of the specimen. Raman shifts at 530 and 840–900 cm^?1 are attributed to C–O and C–C–O stretching in cellulose (remain unchanged). The role of extractives in weathering of pine is shown by the disappearance of Raman shifts at 392 and 434 cm^?1 (C=C deformations in pine extractives) in weathered pine. One-Way ANOVA, between-group designs showed significant effect on brightness (L*), redness (a*) and yellowness (b*) for all treatments.