Wood density : a tool to find complementary species for the design of mixed species plantations

The successful establishment and growth of mixed-species forest plantations requires that complementary or facilitatory species be identified. This can be difficult in many tropical areas because the growth characteristics of endemic species are often unknown, particularly when grown at potentially higher densities in plantations than in natural forests. Here, we investigate whether wood density is a useful and readily accessible trait for choosing complementary species for mixed species plantations. Wood density represents the carbon investment per unit volume of stem with a trade-off generally found between fast (low wood density) and slow (high wood density) growing species. To do this, we use data collected from 18 highly diverse mixed species plantations (4–23 mostly native species) aged from 6 to 11 years at the time of data collection located on Leyte Island, Philippines. We found significant negative correlations between wood densities and the height of the most abundant species, as well as with measures of overall stand growth and tree diameter size distribution. Not only do species with denser woods have slower growth rates, but also mixed-species plantations with higher average wood density and higher stem density were also less productive, at least in these young plantations. Similarly, stands with a high diversity in wood densities were less productive. There is growing interest in making greater use of native multi-species mixtures in smallholder and community planting programs in the tropics, and our results show databases of wood density values may help improve their design. In the early development stages of plantations, canopy closure and rapid height growth are usually key silvicultural targets, and wood density values can predict the rapid height development of species. If plantations are being grown for the livelihood of small landholders then the best target is to choose some species with different wood densities. This allows an early harvest of low-wood density species for early income, and will also reduce competition for slower growing trees with higher wood densities for later income generation.

Comparing the effectiveness of education and technology in reducing wood smoke pollution: A field experiment

This study describes a field experiment assessing the effectiveness of education and technological innovation in reducing air pollution generated by domestic wood heaters. Two-hundred and twenty four households from a small regional center in Australia were randomly assigned to one of four experimental conditions: (1) Education only – households received a wood smoke reduction education pack containing information about the negative health impacts of wood smoke pollution, and advice about wood heater operation and firewood management; (2) SmartBurn only – households received a SmartBurn canister designed to improve combustion and help wood fires burn more efficiently, (3) Education and SmartBurn, and (4) neither Education nor SmartBurn (control). Analysis of covariance, controlling for pre-intervention household wood smoke emissions, wood moisture content, and wood heater age, revealed that education and SmartBurn were both associated with significant reduction in wood smoke emissions during the post-intervention period. Follow-up mediation analyses indicated that education reduced emissions by improving wood heater operation practices, but not by increasing health risk perceptions. As predicted, SmartBurn exerted a direct effect on emission levels, unmediated by wood heater operation practices or health risk perceptions.

“This is not a burning issue for me”: How citizens justify their use of wood heaters in a city with a severe air pollution problem

Although wood smoke pollution has been linked to health problems, wood burning remains a popular form of domestic heating in many countries across the world. In this paper, we describe the rhetoric of resistance to wood heater regulation amongst citizens in the regional Australian town of Armidale, where wood smoke levels regularly exceed national health advisory limits. We discuss how this is related to particular sources of resistance, such as affective attachment to wood heating and socio-cultural norms. The research draws on six focus groups with participants from households with and without wood heating. With reference to practice theory, we argue that citizen discourses favouring wood burning draw upon a rich suite of justifications and present this activity as a natural and traditional activity promoting comfort and cohesion. Such discourses also emphasise the identity of the town as a rural community and the supposed gemeinschaft qualities of such places. We show that, in this domain of energy policy, it is not enough to present ‘facts’ which have little emotional association or meaning for the populace. Rather, we need understand how social scripts, often localised, inform identity and practice.

The affect heuristic and public support for three types of wood smoke mitigation policies

This study applied the affect heuristic model to investigate key psychological factors (affective associations, perceived benefits, and costs of wood heating) contributing to public support for three distinct types of wood smoke mitigation policies: education, incentives, and regulation. The sample comprised 265 residents of Armidale, an Australian regional community adversely affected by winter wood smoke pollution. Our results indicate that residents with stronger positive affective associations with wood heating expressed less support for wood smoke mitigation policies involving regulation. This relationship was fully mediated by expected benefits and costs associated with wood heating. Affective associations were unrelated to public support for policies involving education and incentives, which were broadly endorsed by all segments of the community, and were more strongly associated with rational considerations. Latent profile analysis revealed no evidence to support the proposition that some community members experience internal “heart versus head” conflicts in which their positive affective associations with wood heating would be at odds with their risk judgments about the dangers of wood smoke pollution. Affective associations and cost/benefit judgments were very consistent with each other.

Mechanics of Polyropylene-Seed-Coat-Fibres Composites AndPolyropylene –Wood Fibres Composites-A Comparative Study

Forestry by-products have potential applications as components of wood composites. Replacement of conventional pine radiata wood-fibres by the fibres from the seeds (SCF) of the by-products, require determining and optimizing the mechanical properties to producing highest quality products. Response to mechanical stress is an important aspect to consider towards partial or full replacement of the wood-fibres by SCFs. In the present study the critical strain energy release rate, and the fracture toughness are derived from the published data. The present work uses rules of mixture to derive the mechanical and the physical properties of the SCF and relates the performance of the composites of the wood-fibres and the SCF to chemical composition, dispersion, weight and Vf of the fibres. We have also derived the Gc, the critical strain energy release rate, KIC, the fracture toughness of the composites.

Miniature cone tip resistance of sand with fly ash using triaxial setup

In a continuation of the authors' recent work, the ultimate tip resistance of a miniature cone using triaxial equipment was determined for samples of dry sand mixed with dry fly ash. The effect of (i) the proportion of fly ash, (ii) the relative density of samples, and (iii) the vertical overburden pressure was examined. It was noted that an addition of fly ash in sand for the same range of relative density leads to a significant reduction in the ultimate tip resistance of the cone (q(cu)). This occurs due to a decrease in the friction angle (phi) of the sample with an increase in the fly ash content for a given relative density. For phi greater than about 30 degrees, two widely used correlation curves from published literature, providing the relationships between q(cu) and phi for cohesionless soils, were found to provide satisfactory predictions, even for sand - fly ash mixtures. As was expected, the values of qcu increase continuously with an increase in the relative density of the soil mass and the vertical effective ( overburden) stress on the sample.

Prediction of compressive strength of SCC and HPC with high volume fly ash using ANN

An artificial neural network (ANN) is presented to predict a 28-day compressive strength of a normal and high strength self compacting concrete (SCC) and high performance concrete (HPC) with high volume fly ash. The ANN is trained by the data available in literature on normal volume fly ash because data on SCC with high volume fly ash is not available in sufficient quantity. Further, while predicting the strength of HPC the same data meant for SCC has been used to train in order to economise on computational effort. The compressive strengths of SCC and HPC as well as slump flow of SCC estimated by the proposed neural network are validated by experimental results.

Predicting wood value in Queensland Caribbean pine plantations using a decision support system

A decision support system has been developed in Queensland to evaluate how changes in silvicultural regimes affect wood quality, and specifically the graded recovery of structural timber. Models of tree growth, branch architecture and wood properties were developed from data collected in routine Caribbean pine plantations and specific silvicultural experiments. These models were incorporated in software that simulates the conversion of standing trees into logs, and the logs into boards, and generates detailed data on knot location and basic density distribution. The structural grade of each board was determined by simulating the machine stress-grading process, and the predicted graded recovery provided an indicator of wood value. The decision support system improves the basis of decision-making by simulating the performance of elite genetic material under specified silvicultural regimes and by predicting links between wood quality and general stand attributes such as stocking and length of rotation.

Field assessment of the resistance of timber products to termite (Isoptera) damage: Results can change with the amount of bait wood

Whether or not termites initiate damage to timber via the end grain may determine the need for spot-treating the exposed untreated cut ends of envelope-treated softwood framing material. Australian Coptotermes acinaciformis (Froggatt) were field-tested for their ability to initiate feeding via the end grain of timber (35 × 90 mm) treated with a repellent Tanalith® T envelope. Specimens of commercial radiata pine Pinus radiata D.Don framing timber (untreated) and slash pine Pinus elliottii Englem. (untreated and envelope-treated) were partially clad in fine stainless steel mesh. Clad and unclad specimens were exposed to C. acinaciformis near Townsville, North Queensland, Australia, for four months. Results showed that this species of termite can indeed damage timber via the end grain, including exposed untreated cut ends of envelope-treated material as demonstrated earlier for different populations of C. acinaciformis. Differences between the test conditions in field trials carried out at different times (where C. acinaciformis either did or did not damage timber via the end grain) are discussed. Clearly, outcomes from field studies with preservative-treated materials are dependent upon experimental conditions. Notably, the amount of bait wood (highly termite-susceptible timber substrate) offered in a given method can strongly influence the termite response. Further investigation is required to standardise this aspect of conditions in protocols for the assessment of wood preservatives.

Quantitative assessment of total phenol contents of European oak (Quercus petraea and Quercus robur) by diffuse reflectance NIR spectroscopy on solid wood surfaces

Near infrared spectroscopy (NIRS) combined with multivariate analysis techniques was applied to assess phenol content of European oak. NIRS data were firstly collected directly from solid heartwood surfaces: in doing so, the spectra were recorded separately from the longitudinal radial and the transverse section surfaces by diffuse reflectance. The spectral data were then pretreated by several pre-processing procedures, such as multiplicative scatter correction, first derivative, second derivative and standard normal variate. The tannin contents of sawmill collected from the longitudinal radial and transverse section surfaces were determined by quantitative extraction with water/methanol (1:4, by vol). Then, total phenol contents in tannin extracts were measured by the Folin-Ciocalteu method. The NIR data were correlated against the Folin-Ciocalteu results. Calibration models built with partial least squares regression displayed strong correlation - as expressed by high determination correlation coefficient (r2) and high ratio of performance to deviation (RPD) - between measured and predicted total phenols content, and weak calibration and prediction errors (RMSEC, RMSEP). The best calibration was provided with second derivative spectra (r2 value of 0.93 for the longitudinal radial plane and of 0.91 for the transverse section plane). This study illustrates that the NIRS technique when used in conjunction with multivariate analysis could provide reliable, quick and non-destructive assessment of European oak heartwood extractives.

Potential for using through-boring to improve groundline treatment of Australian wood species: A preliminary study.

An aging electricity distribution system and reduced availability of naturally durable tropical hardwoods in Australia will combine in the next decade to produce a major shortage of poles. One approach to mitigating this shortage is to utilize lower durability species and improve the penetration of preservatives into the refractory heartwood by introducing additional pretreatment processes. A potential method for improving preservative penetration in the critical ground-line zone is through-boring. This process, in which holes are drilled through the pole perpendicular to the grain in the ground-line zone, is widely used in the western United States for treatment of Douglas-fir and may be Suitable for many Australian wood species. The potential for improving heartwood penetration in eucalypts with alkaline-copper-quaternary (ACQ) compound was assessed on heartwood specimens from four species (Eucalyptus cloeziana F.Muell., E. grandis W.Hill ex Maiden, E. obliqua L'Her. and E. pellita F.Muell.) and Lophostemon confertus (R.Br.) Peter G.Wilson & J.T.Wateril). Longitudinal ACQ penetration was extremely shallow in L. confertus and only slightly better in E. cloeziana. Longitudinal penetration was good in both E. obliqua and E. pellita, although there was some variation in treatment results with length of pressure period. The results suggest that through-boring might be a reasonable approach for achieving heartwood penetration in some Eucalyptus species, although further studies are required to assess additional treatment schedules and to determine the effects of the process oil flexural properties of the poles.