Feedback report to the Hans Merensky Foundation: June 2017

Brand Wessels, Department of Forest and Wood Science, Stellenbosch University
E-mail: cbw@sun.ac.za | Tel: 021-8083319

This is a feedback report for the different projects and students that HMF funded in 2017 at the Department of Forest and Wood Science, Stellenbosch University.

Project 1:  Improving the value yield from the sawn lumber value chain: New sawlog plantation management regimes for SA Pine

Several research projects confirmed the reduction in mechanical properties of fast grown SA Pine species harvested at a young age. This project explores the potential of forest management regimes to improve mechanical wood properties of SA pine species through higher planting densities and late thinnings. The main objective of the current study is developing a basic understanding of the underlying mechanisms responsible for the changes in wood properties of pine grown under different competitive environments. The project is co-funded by ForestrySA and some of its members.

For 2017, the PhD study of Justin Erasmus involves (a) the modelling of stiffness (MOE) of Pinus patula lumber, and (b) modelling cambial cell development of Pinus patula with a focus on identifying the drivers of variation in MFA, cell properties and also density. A spacing trial has been destructively tested and all experimental work on this trial has been completed including flexural testing of lumber, Silviscan measurements of density, cell properties and MFA, and measurement of other wood properties. Statistical analysis of data is in progress after which a predictive model will be developed for MOE. A greenhouse trial of P. patula, P. elliottii X caribaea, and P. patula  tecunumanii has also been established in Stellenbosch at the end of 2016. Trees are subjected to different water availability, nutrition, and wind conditions. This trial will continue till mid 2018 before wood properties will be measured.

The MSc study of Francis Zhangazha involves the analysis of the effect of altered thinning and pruning regimes on the branch and knot properties of Pinus patula. All experimental work including destructive sampling of trees from four different treatments from the KZN region, and evaluation of knot properties was completed. The student is currently busy with the analysis of data.

The MSc project by Ryan Charlton use growth and manufacturing process modelling of Pinus patula to develop an economic model which can be used to assess different forest management options for Pinus patula. The full value chain from plant to final product will be included in the model. Lidar scanning of a spacing trial has been completed and analysed for tree form – results will be imported into a sawmill simulation model. Wood quality data has been obtained from the same spacing trial to assess value differentiation between different management options. Forest growth and processing modelling is in progress. A sensitivity analyses will also be completed to identify the areas in the value chain with the best potential for increases in financial returns.

The MSc project of Vhuhwavho Tshavhungwe focus on the variation in the mechanical properties of lumber in sawmills when a wide variety of tree species and forest management regimes are used. The use of statistical process control to ensure compliance to national standards for mechanically graded lumber will be investigated. Literature research and a proposal has been completed and the student is currently planning experimental work.

Adeyinka Adesope recently started a PhD study on the cell formation process of Pinus patula with a specific focus on the switch between earlywood and latewood formation. He has completed a literature research and is busy analysing data from earlier projects before finalising a proposal.

Project 2: Green building with wood

The previous phase of this project focused on life cycle assessment (LCA), green rating, and environmental sustainability of South African building materials – including wood. The outcome of this phase was proof of the huge comparative advantage that wood in South Africa has in terms of environmental sustainability compared to competitive materials. The next question is to what extent can the South African building sector change towards more environmentally friendly wood based materials? We are a timber scarce country and using wood as a building material may lose many of its environmental benefits if it has to be imported from far-away countries. PhD student Phillip Crafford is busy with a regional timber supply and demand study to analyse possible sources of raw materials over the next two decades (including SADC countries). An LCA study quantifying the environmental impact of logistics and specifically imports from SADC countries, South America, Canada, Europe as well as regional transport in South Africa has been completed and is currently being prepared for submission as a journal paper.

Project 3: Green gluing of eucalyptus lumber

In the first two years of this project the advantages of the basic concept of green edge-gluing of Eucalyptus grandis has been confirmed. The next two years will focus on specific technical challenges of using E. grandis in specific product classes.

MSc student Michael Dugmore is nearly finished with experimental work on delamination behaviour and testing methods in E. grandis cross-laminated timber. This work is done in cooperation with the IVALSA institute in Italy. Sizwe Gonya started an MSc study on the shrinkage and collapse behaviour of E. grandis wood. He will investigate the variability of these properties in a tree as well as the basic factors influencing shrinkage and collapse. Literature research and proposal writing has been completed and experimental work is currently planned. Calvin Pagel has started an M Eng degree at Civil Engineering which will be co-supervised by myself. He is investigating the partial material factors to be used in designing structures from composite  Eucalyptus grandis products. The first year of M Eng is spent on compulsory subjects and he has not started with his project yet.

Project 4: Non-destructive testing on standing E. grandis trees for wood quality

The objective of this project is to identify potential non-destructive prediction tools and methodologies on Eucalyptus grandis that can be used to estimate splitting, dimensional stability, brittle heart, collapse, density and density gradient at a relatively early age. This is especially important for early selection of superior genetic material for tree breeding purposes. Ashlee Prins started an MSc study on this issue and completed a literature search and proposal and is busy with planning of experimental work.

Research outputs of 2016-2017 by HMF funded projects and students:

Blumentritt M, Pröller M, Wessels CB. 2016. Innovative use of eucalyptus timber for structural applications in South Africa. European Hardwood Conference, 8-9 September, Sopron, Hungary.

Crafford PL, Wessels CB. 2016. A potential new product for roof truss manufacturing: Young, green finger-jointed Eucalyptus grandis lumber. Southern Forests: a Journal of Forest Science 78(1):61-71

Crafford PL, Wessels CB, Blumentritt M. In press. The potential of South African timber products to reduce the environmental impact of buildings. South African Journal of Science

Erasmus J, Kunneke A, Drew DM, Wessels CB. Accepted subject to modifications. The effect of planting spacing on Pinus patula stem straightness, microfibril angle and wood density. Forestry

Erasmus J, Wessels CB. Accepted subject to modifications. A comparison of wood and lumber properties of Pinus patula stands planted at different stem densities. Forestry

Lerm FJ, Blumentritt M, Brink WH, Wessels CB. 2017. A method for three-dimensional stem analysis and its application in a study on the occurrence of resin pockets in Pinus patula. European Journal of Forest Research, DOI 10.1007/s10342-017-1041-8

Munalula F, Blumentritt M, Seifert T, Wessels CB. 2016. A method for determining knotty core sizes of standing Pinus patula trees based on tree ring sampling. Dendrochronologia 38: 11-17.

Pröller, Marco. 2016. An investigation into the edge gluing of green Eucalyptus grandis lumber using a one-component polyurethane adhesive. MScFor (Wood Products Science) thesis.

Wessels CB, Crafford PL, Du Toit B, Grahn T, Johansson M, Lundqvist S-O, Säll H, Seifert T. 2016. Variation in physical and mechanical properties from three drought tolerant Eucalyptus species grown on the dry west coast of Southern Africa. European Journal of Wood and Wood Products 74: 563-575

Wessels CB, Froneman GM, Erasmus J. 2016. The influence of initial planting density on lumber stiffness and other wood properties of South African-grown P. radiata, P. elliottii, and P. patula. WOOD QC 2016 conference: Modelling wood quality, supply and value chain networks, June 12-17, Baie-St-Paul, Quebec, Canada.