Southern Forests: a Journal of Forest Science

Sawmilling competitiveness from the perspective of industry competitiveness models: a review

Vhuhwavho Tshavhungwe, Schalk Grobbelaar — Thu, 18 Apr 2024 00:00:00 +0000

Globalisation and changes to the world economy have brought new challenges and opportunities for many industries, including the sawmill industry. This has led to a need to evaluate the competitiveness of South Africa’s sawmilling industry by studying the factors affecting competitiveness in other sawmill industries. The review evaluated published research on sawmill industry competitiveness to identify and address the research gaps in the literature. The systematic literature review implemented a PRISMA protocol. Sankey diagrams showed the relationships between the factors driving change and those affecting competitiveness. The results showed that most factors affecting and driving industry competitiveness were similar. The reviewed papers pointed to the availability of wood, formation of clusters, policy implications, level of innovation and employment conditions as the factors affecting industry competitiveness. The research findings corresponded to some of the early ideas presented by Michael Porter on industry competitiveness. The research will guide future research on the South African sawmill industry.

An investigation into the flexural properties of sawn timber and poles of South African grown Pinus maximinoi (H.E.Moore)

C Brand Wessels, Christel Malek, Gary R Hodge, Bruno Monteiro Balboni — Thu, 18 Apr 2024 00:00:00 +0000

Pinus maximinoi is a species that can potentially be deployed commercially to provide structural timber and poles for the South African market. The objective of this study was to investigate the flexural properties of sawn timber and poles of P. maximinoi from young plantations of the Southern Cape. A total of 60 trees and 150 logs for the sawmill study were obtained from two research trials on the Longmore estate in the Humansdorp area (13.7 years old), and on the Kruisfontein estate close to Knysna (9.0 years old). Some 74 poles from the same compartments were removed and tested in bending. The P. maximinoi sawn timber had excellent bending properties, superior to sawn timber from other South African Pinus species, tested at similar radial positions in previous studies. Analysis of variation showed that site, log height and board radial position had a significant influence on the modulus of elasticity (MOE) of sawn timber. Multiple regression analysis showed that board MOE can be predicted using a model including tree taper, time-of-flight measured with Treesonic and wood density (model R² = 0.87). The P. maximinoi poles complied with the mean MOE national standard requirement SANS 457-2 of 9 000 MPa but not with the fifth percentile (bending strength) modulus of rupture (MOR) requirement of 34 MPa. This study and other research, however, showed that the national standard requirement for MOR of poles might be too high for current log resources in South Africa. The investigation into the bending and other properties of P. maximinoi sawn boards and poles showed extremely positive results. Based on this wood quality study of P. maximinoi, it is certainly a very promising species for deployment in the Southern Cape and potentially other regions in South Africa.

Estimation of lumber recovery for small-scale mobile sawmills in Tanzania

Thu, 18 Apr 2024 00:00:00 +0000

Lumber recovery is an important parameter in determining the production efficiency and viability of mobile sawmilling operations. In this study, lumber recoveries for mobile sawmilling machines operating in four different locations in Tanzania were estimated. A total of 11 mobile sawmilling operations were studied. On each piece of mobile sawmilling machinery, data on log sizes, including bottom, mid and top diameter, and log lengths were recorded. Results showed that the number of logs per machine ranged from 5 to 40 with an average of 28 logs. The middle diameter of the logs ranged from 8 to 44.60 cm, with an average value of 20.58 cm. The number of lumbers produced for each log varied from 1 to 9 pieces, with an average of 3 pieces across all the sites. The lumber recovery (%), varied depending on the individual machine, machine type, source of logs and geographical site within Tanzania. For all the machines, the average lumber recovery (%) per machinery ranged from 16.15 to 62.79%. Among the three types of mobile sawmilling machinery, Wood-Mizer had relatively higher lumber recovery (56.2%) than Ameck and Ding-Dong. The overall average lumber recovery value for all the machines, irrespective of log sizes, site and source of lumber was 43.34%. Analysis of variance (ANOVA) indicated that site, source of lumber, machine type and size of logs had a statistically significant effect (p < 0.05) on lumber recovery (%). The study concluded that mobile sawmilling in Tanzania produces sawn timber with reasonable lumber recovery. However, further studies are recommended to examine technical aspects, such as productivity and taper, as well as cost of the mobile sawmilling operations.

Detecting canopy openings in logged-over forests: a multi-classifier analysis of PlanetScope imagery

Thu, 18 Apr 2024 00:00:00 +0000

This study focused on the detection of forest canopy openings resulting from harvesting activities in hill tropical forests. Canopy openings, whether natural or human-induced, can have detrimental effects on forest ecosystems. Traditional ground surveys to assess the extent of canopy opening can be challenging and time-consuming. Therefore the study aimed to utilise satellite imagery, specifically PlanetScope data, to detect, map and measure canopy openings in logged-over forests. Three different classification algorithms, namely maximum likelihood classifier (MLC), support vector machine (SVM) and object-based image analysis (OBIA) were used and compared to identify canopy opening areas. The assessment was conducted in two stages: a preliminary assessment with three classes (forest, canopy opening and shadow) and a final assessment with two classes (forest and canopy opening). The overall accuracies of the classification algorithms were 82% for MLC, 91% for SVM and 90% for OBIA. Both SVM and OBIA surpassed the
accuracy threshold, with SVM being the most effective in detecting and extracting canopy openings in dense forests. Results demonstrated the potential of PlanetSope imagery and advanced classification algorithms to detect canopy openings in logged-over forests. The findings highlighted the importance of regular updates on canopy opening extent, particularly concerning sustainable forest assessment and minimising the negative impacts on forest ecosystems.

Pathogenicity of Chrysoporthe deuterocubensis on eucalypts in Indonesia

Thu, 18 Apr 2024 00:00:00 +0000

Several economically important pathogens, including species of Chrysoporthe, pose a threat to the rapidly expanding eucalypt plantation industry in Southeast Asia. During 2019 disease surveys in Riau and Kalimantan (Indonesia), cankers were observed on eucalypt trees and a collection of fungal isolates was obtained from them. The aim of this study was to confirm the identity of the isolates and to evaluate their relative pathogenicity on different eucalypt clones. Using the DNA sequence data based on the internal transcribed spacer (ITS) region of the ribosomal DNA and two regions of the β-tubulin gene (TUB1 and TUB2), 31 fungal isolates were identified as C. deuterocubensis. Pathogenicity trials showed that C. deuterocubensis isolates differed in their pathogenicity and that different eucalypt genotypes differed in their susceptibility to the pathogen. These results will provide valuable information to reduce the threat of stem canker to future eucalypt plantation development.

Zoning the occurrence of Thyrinteina arnobia in eucalypts and its relationship with the spectral behaviour of canopies and soil attributes

Thu, 18 Apr 2024 00:00:00 +0000

This study aimed to outline areas at risk of the occurrence of eucalypt defoliator caterpillars and their relationship with variations in the spectral behaviour of canopies and soil attributes. The study was conducted in three eucalypt plantation areas of the Bracell Bahia company, located in the state of Bahia, Brazil. Initially, the spatiotemporal distribution of climatic variables and water balance was evaluated. Subsequently, using geographic information systems and fuzzy logic, occurrence risk zoning was developed for defoliator caterpillars associated with different classes of eucalypt crop aptitude. After defining the areas at risk of pest occurrence, specific plots in different aptitude classes were selected to assess, intra-plot, characteristics that can increase or reduce the risk of defoliator caterpillar attack and damage intensity, as well as the plant’s ability to recover after a controlled outbreak. Information on the spectral behaviour of the canopies and the availability of nutrients in the soil was used in this step. Zone modelling enabled the delineation of areas and periods at a higher risk of pest occurrence for the different aptitude conditions of the eucalypt crop. The intra-plot methodology proved that the class of eucalypt crop aptitude with the greatest potential for recovering vegetative vigour 60 days after caterpillar damage was the apt class. This result can be attributed to K limitation and the high spatial resolution of the PlanetScope orbital sensor.

Growth, vegetative rescue and vegetative propagation in Eucalyptus species and hybrids

Thu, 18 Apr 2024 00:00:00 +0000

The objective of the study was the evaluation of survival and productivity indicators in different species/hybrids of Eucalyptus in the adult stage, as well as the vegetative rescue of adult trees and cuttings, testing for species/hybrids, concentration of growth regulator and substrates in rooting. In the evaluation of species/hybrids, height (m), diameter at breast height (DBH, cm) and individual volume (m³ per individual) were measured, and survival was evaluated. In the vegetative rescue treatment, the number of shoots produced at 90, 120 and 210 days was evaluated. In the cutting experiments, the species that produced rescue shoots were tested, in addition to indole-3-butyric acid (IBA) doses (0, 1 500, 3 000 and 4 500 mg L⁻¹) and four substrates for rooting cuttings. The experiments of IBA doses and substrates were carried out using Eucalyptus saligna plants. In the cutting experiments, after 120 days of cultivation, the following variables were evaluated: callus formation (%), survival (%), rooting (%), number and length of roots. The best results regarding survival and quantitative variables of the species/hybrids were obtained for E. dunnii, E. dunnii × E. grandis and E. pellita. In the vegetative rescue, E. dunnii × E. grandis and E. pellita had the highest formation of shoots and the girdling vegetative rescue method had the best results in terms of generated shoots. E. saligna had better results regarding the variables related to the rooting of cuttings. The substrate S3 and the use of 1 500 mg L⁻¹ of IBA provided the highest survival rate and better variables related to the rooting of the cuttings.

Amendment notice

Publishing Manager — Thu, 18 Apr 2024 00:00:00 +0000

No abstract