Climate change & forestry sustainability on research radar

Sappi Research Chair launched at Wits (left to right) Dr Tracy Wessels (Sappi Ltd), Prof Mary Scholes (Wits) and Giovanni Sale (Sappi Forests).

Professor Mary Scholes is heading up a research initiative on climate change and plantation sustainability at Wits University, supported by Sappi …

Sappi Southern Africa and the University of the Witwatersrand (Wits) have established a Sappi Chair in Climate Change and Plantation Sustainability. This initiative aligns with Sappi’s drive to generate technical and operational solutions which mitigate against climate change risks and to enhance reporting on carbon emissions, climate change and sustainability.

Professor Mary Scholes, an internationally recognised authority on tree physiology and climate change and who is affiliated with the research platform in the Wits School of Animal, Plants and Environmental Sciences, will act as the Research Chair.

The work by Wits will help to enhance Sappi’s planning process and overall competitiveness.

“Because forestry is a long-term crop, the industry needs to know well in advance where to direct their resources and investment and needs the most accurate climate models to rely on,” says Prof Scholes.

She will identify critical research needs and develop research outputs related to climate change, which is one of the University’s eight research priorities. She will also lead the development of capacity to manipulate and interpret climate modelling data.

Speaking at the launch, Tracy Wessels, Sappi Group Head of Sustainability and Investor Relations, commented: “The creation of this Chair demonstrates Sappi’s commitment to building a thriving world through strong partnerships, supporting innovation and investing in future research capabilities.

“Like all other agricultural crops, the trees in the 399,996 hectares of land we own and lease are negatively impacted by climate change. While we practise climate-smart forestry and while our research teams have been hard at work developing drought resistant genotypes, the temperatures over the South African interior are projected to rise at about 1.5 to 2 times the global rate of temperature increase.

“In addition, there is increasing global pressure to account accurately for greenhouse gas emissions from forests, land and agriculture. Against this backdrop and in line with our commitment to UN SDG13: Climate Action, the need to develop climate solutions has intensified, which is why our sponsorship of the Sappi Chair in Climate Change and Plantation Sustainability makes sound business sense.”

Sappi’s initial sponsorship of the Research Chair will run until 2026.

Sappi’s association with Wits is not new: In 2020, Sappi began working on a project with other industry members and the Wits Global Change Institute on a project which involved the generation of raster climate surfaces for the entire forestry domain of South Africa, at a resolution of eight kilometres, with monthly time resolution, for the years 2020, 2030 and 2040 to 2100.

Red flag over deteriorating health of forest soils

Planting successive rotations of the same tree species on the same piece of land over and over is likely to have a negative impact on soil health and long term productivity of the site will decline – especially when the residue from the previous harvest has been burnt off, leaving the soil unprotected from the elements, as is the case with this community forestry enterprise in Eastern Cape.

Planting the same tree species over successive rotations carries a high risk of deteriorating soil health, say FABI researchers …

It is widely accepted in agriculture circles that practicing crop rotation is beneficial for soil health. This is because the continuous cultivation of the same plant species on the same piece of land over and over again impacts negatively on soil health, and leads to a build-up of harmful micro-organisms. There is plenty of scientific evidence to support this theory.

To address this issue, good farmers all over the world practice crop rotation, planting different crops over successive rotations, or do inter-cropping where for instance they will plant a legume in between rotations to improve soil health and biodiversity.

Many small-scale tree farmers in Zululand practice inter-cropping, planting mielies, beans or peanuts in between their Eucalyptus seedlings when they are still small, and before the canopy closes. This could be beneficial for soil health.

So why not treat short rotation tree crops the same way – and if we don’t, and we keep on planting the same species rotation after rotation, will we eventually find that soil health deteriorates to the point where the trees will no longer grow properly?

Common sense would suggest that this will be the case, but there is no ‘conclusive’ scientific evidence to support this theory. In any event crop rotation in forestry is not so easily done as rotation lengths are long (8 – 20 years), land available for forestry is limited (in South Africa) and only three species are widely grown – eucalypts, pine and wattle – all of which are geared to serve specific markets.

Moreover improvements in silvicultural practices and advances in tree breeding have thus far masked any impacts of deteriorating soil health on successive tree crops, thus reducing growers’ appetite for experimenting with crop rotation...

This Sappi compartment in Zululand has been mulched and the residue retained to cover the soil with a nutrient-rich layer that provides protection, retains moisture and gives the young trees a growth boost.

But now a group of highly regarded researchers have raised a red flag and warned that deteriorating soil health is a real risk for short rotation plantation forestry, as it is practiced in South Africa and in many other parts of the world.

A team of FABI researchers including Dr Tanay Bose, Prof Bernard Slippers, Almuth Hammerbacher, Jolanda Roux and Mike Wingfield, have analysed existing data on soil microbiomes from short-rotation forestry environments around the world which, they say, provides evidence that a build-up of harmful micro-organisms, depletion of beneficial micro-organisms, and deterioration of the physical and chemical properties of soil can result from continuous replanting of the same tree species on the same piece of land.

“Populations of unfavourable microbes can be expected to become more abundant over successive rotations,” state the FABI researchers in an article published in the journal Current Forestry Reports. “This is strongly supported by data from recent soil microbiome studies involving commercially managed forests, which provide convincing evidence of an increase in pathogenic microbes in soils of continuously replanted forests.”

Building on these findings and considering similar approaches in agriculture, the team proposes a number of practical solutions that have the potential to mitigate the deterioration of soil health resulting from planting the same species over successive rotations.

Weza farmer Jon Mackenzie uses a tractor-powered chipping machine to chip the post-harvest residue after clear felling, which is then spread evenly over the site before the re-planting operation begins. This is his strategy to conserve the health of the soil on his farm for the log term.

• Retaining post-harvest residue on the site is likely to result in healthier soils over successive rotations. This is why many growers have stopped burning the post-harvest residues and have opted for mulching or chipping.
• Application of biochar has considerable potential to enhance soil properties, nutrients and microbes in continuously replanted forests. Biochar is a carbon-rich, stable organic product made from the pyrolysis of organic biomasses such as leaves, sawdust, animal dung and wood. During carbonization, biochar releases phosphate into the soil along with other mineral nutrients, improving its fertility. Biochar also improves the physical properties and microbial biodiversity of the soil, which could further increase soil nutrient availability and carbon storage. However more research is needed to assess the impact of biochar on plantation soils.
• Crop rotation and intercropping could alleviate the negative consequences of continuous replanting of the same species in short-rotation plantation forestry. For example, rotating between eucalypts, black wattle and pine species could prevent the accumulation of harmful soil microbes detrimental to these trees. Rotating nitrogen fixing leguminous tree species such as Acacia with eucalypts or pines has the potential to further promote both soil and tree health increasing the availability of nitrogen in the soil and improving the quality of plant litter.
• Practicing agro-forestry, where different crops are inter-planted on the same piece of land, would also have a positive impact on soil health.
• Innoculation of tree seedlings in the nursery with beneficial microbes.
“Continuous replanting practised in short-rotation plantation forests is likely to be accompanied by a high risk of ‘replanting syndrome’ in plantations. While long-term monitoring programs to document the changes in soil microbiomes are still lacking and should be urgently initiated, the available evidence suggests that short-rotation forest plantation enterprises could be restrictive when successively establishing plots with the same or nearly the same genotypes,” the FABI team concluded.

Mulching after clear felling is an expensive exercise, but many growers have opted for this approach instead of burning off post-harvest residues, in the interests of boosting soil health for the long term.

For the full Report see: Current Forestry Reports.

FSA secures R18 m funding for forest protection

A Memorandum of Agreement (MoA) concluded between Forestry South Africa and the Department of Forestry, Fisheries and the Environment (DFFE) is set to boost industry’s efforts to counter the impact of pests and diseases on the country’s timber resources with the injection of R18 million funding over two years.

“While long overdue, this partnership with DFFE will add greatly to our efforts to protect our timber resources against pests and diseases, conduct desperately needed research and development, build our human capacity in this crucial area and encourage ongoing investment by our sector,” commented FSA’s Research and Forest Protection Director, Ronald Heath.

The MoA focuses on five main outcomes:-

• Monitoring activities
• Awareness programmes
• Provision of diagnostic services to the forestry industry
• Conducting research on aspects of pests and diseases.

The MoA will be managed on behalf of the Industry by Ronald Heath with oversight provided by the National Pests and Diseases Steering Committee which includes representatives from DFFE, FSA, the National Forest Research Forum and the Tree Protection Cooperative.

After five years of continuous and active engagement with the DFFE, the process was concluded in the short space of one month thanks to the efforts of Mohammed Bhabha of the PPGI, Sabelo Malaza from the Masterplan Programme Management Office in DFFE and Director-General Tshabala, said Ronald.

The importance of securing this funding support from DFFE is underlined by the increasing impacts of pests and diseases on forestry in South Africa and around the world.

It is estimated that over the past 30 years the forestry industry has been losing the equivalent of 11.5% of its harvest to pests and diseases every year. When using current value estimates of 50% of the average value of the timber, the losses amount to R392 million of roundwood annually. This translates into an opportunity cost of R2,05 billion in additional downstream processing that is lost.

The losses outlined above - which exclude losses due to fire - have arisen from just a handful of pests and diseases. Now, with the rate of new pests and diseases landing on our shores increasing rapidly on the back of expanding global trade, the losses incurred from pest and disease damage are expected to increase dramatically in future.

Are multi-storey timber buildings viable in South Africa?

Research by a structural engineer finds that construction of multi-story timber buildings would be financially feasible in South Africa, but that suitable timber would need to be imported as local resources are ‘over-subscribed’ …

The economic viability of multi-storey mass timber buildings in South Africa has come under the spotlight in a research study carried out by Stephanus van der Westhuyzen, a Structural Engineer at leading consulting engineering and infrastructure advisory firm Zutari.

Sawmilling South Africa (SSA) and the Institute for Timber Construction South Africa (ITC-SA) have both proposed that timber be designated a construction material of choice. This will assist in alleviating the housing crisis in densely populated informal settlements that have been hardest-hit by the Covid-19 pandemic, where quality accommodation needs to be built as quickly and as cost-effectively as possible.
Timber as a building material can substantially reduce greenhouse gas (GHG) emissions in the building sector, in addition to reducing the waste, pollution and costs associated with construction, and thereby contribute to a more physically, psychologically and aesthetically healthy built environment.

Van der Westhuyzen’s research focuses on whether or not South African plantations can provide sustainable volumes of high-grade (S7, S10) timber to sustain a multi-storey mass timber building market. This was followed by the design of two eight-storey commercial buildings consisting of a mass timber frame and a reinforced concrete frame respectively.

A focus-group workshop conducted with industry professionals assisted with developing the construction schedules, while a financial model was used to determine the overall development cost and financial feasibility of the two approaches. Finally, a sensitivity analysis was conducted to investigate the effect of certain variables on the overall profitability of the mass timber frame option in particular.

The research revealed that mass timber products would need to be imported to satisfy the rapid growth in the multi-storey mass timber building market in South Africa, as current timber supplies (S5, S7, S10) are oversubscribed. Studies suggest that future log resources could be added to the market through the development of new plantations, although the reality is that the opportunities for establishing additional plantations in South Africa are extremely limited. In any event it would take a minimum of 24 to 30 years before any new plantations could produce suitable construction grade timber.

The focus group workshop found that construction of the reinforced concrete frame building would take 42 weeks, while the mass timber frame building would take 21 weeks to build. Furthermore, the total capital investment required for the mass timber frame building would be 10% more than that of the reinforced concrete frame option. The five-year internal rate of return (IRR) of the timber building would be 20.9% vs 25.7% for the reinforced concrete frame option.

Notably, the five-year IRR of both options is above the 15% minimum acceptable rate of return (MARR), indicating that they are both financially feasible. A significant finding of the sensitivity analysis was that the mass timber frame building proved to generate a higher five-year IRR than that of the reinforced concrete frame once the mass timber building achieved a rental premium of 7.8% or more. The sensitivity analyses further revealed that importing mass timber elements is an expensive option at a 16.4% five-year IRR.

The research study highlighted a number of aspects in the manufacturing sector that can be addressed to develop a sustainable multi-storey mass timber building market. This includes improving the sourcing of high-grade structural timber (S7, S10) and investing in equipment to enable the large-scale production of large beams and columns typically required in multi-storey mass timber structures.

Due to the sturdy and resilient qualities of timber and the relative ease of construction, timber-frame construction is one of the oldest known building methods, especially in the Northern Hemisphere. While timber construction in South Africa can be traced back to the 1800s, it only became a bona fide building method over the last 30 years.

This resulted in the formation of the Timber Frame Builders’ Association in the early 1980s, with SABS 082 amended in 1988 to include standards for timber construction in particular. The Institute of Timber Frame Builders (ITFB) and the ITC were aligned in August 2014, with the ITC-SA established to promote and sustain timber engineered products in South Africa.

To read the full thesis by Stephanus van der Westhuyzen, click HERE.

EucXylo team set to grow

A small nursery of 12 newly planted Eucalyptus trees near the Department of Forest and Wood Sciences at Stellenbosch University (SU) represents more than just a research project in the making. The trees are symbols of growth, and of the shaping of bright minds through the endeavours of the Hans Merensky Research Chair in Advanced Modelling of Eucalyptus Wood Formation (or EucXylo).

The flourishing nursery trees also serve as a living memorial to the mining geologist, scientist and prospector, Dr Hans Merensky, a pioneer of forestry and agriculture in South Africa, who was born 150 years ago. The Hans Merensky Foundation is making the work of EucXylo possible.

Aptly therefore, most of the work and laboratory space that this young research group occupies is in the wood-panelled Hans Merensky wing of the Department of Forestry and Wood Science’s Paul Sauer building.

“Through the research done by our postgraduate students and younger researchers we aim to better understand the dynamics behind how the wood of Eucalyptus trees form. They are among others developing appropriate mathematical and computational models and delving into how climate change is and will influence the way in which such species grow,” says EucXylo research leader and senior lecturer Prof David Drew of the SU Department of Forestry and Wood Science.

“Wood formation, technically known as xylogenesis, is fundamental to the fixing of carbon dioxide into the stable, valuable and beautiful material we call wood, and to the production of our planet’s increasingly-important renewable timber resources,” he explains. “We are trying to understand and model the processes of wood formation of Eucalyptus in the context of the physiology of the whole plant, and not only the molecular genetics of wood formation.”

About the Research Chair’s very specific focus on one type of tree, he says: “Eucalyptus or gum trees are arguably the world’s most widely planted hardwood forest species. Their wood is used for a wide variety of purposes, ranging from pulp to solid wood for construction. Most research done on wood formation has so far come from the northern hemisphere and was done on small plant species and poplar and other softwood tree species.”

The group consists of four MSc students, five PhD candidates, two postdoctoral researchers and a technical officer.

PhD student Gugu Gama, who hails Newcastle in KwaZulu-Natal, says she joined the team because of her interest in wood anatomy. “I wanted to further my skill set in this field. This research team encompasses modelling, images analysis and modern computational analysis of wood with a focus on interesting species such as Eucalyptus.”

The Research Chair was established in 2019, with most of the team members joining during the course of the past year. To broaden its scope, the EucXylo team is collaborating closely with scientists in the SU faculties of Agrisciences and Science, and with various leading international researchers.

Prof Drew adds: “To some our research might seem very ‘blue skies’, but I am sure Dr Merensky would have approved of the way in which our endeavours are extending the skills base and research abilities of younger scientists-in-the-making. In this way we are making sure that there are enough bright young minds to fill positions within the forestry and wood sector, in South Africa and abroad.”

Climate change research
Prof Drew notes that his team has received more than just direct funding from the Merensky rank towards its endeavours: “The trees in our nursery were for instance also provided by the Merensky Forestry section and are doing well.”

The trees are being cared for by Mpilo Kumalo, as part of his PhD in Forestry and Natural Resources Sciences. He is drawing on his knowledge of ecosystem ecology and ecophysiology to study seasonal variation in Eucalyptus wood formation, and the relationship between sap flow and wood formation, to understand how it influences the architecture of a tree.

In another part of the nursery complex Raphael Keret is constantly taking plant measurements as part of his PhD in Plant Biotechnology. In light of climate change and changing rainfall patterns, he is investigating the ways in which water stress and droughts influence the movement of sap in trees – and ultimately also influence wood characteristics.

In related work, Alta Saunders, a PhD in Forestry candidate, is using measurements taken in the nursery to build computational models with which to understand how Eucalyptus trees respond to drought situations, how they recover, and the role of stomatal conductance (the rate of water loss through leaves) in all of this.

Diverse fields
Prof Drew is described by his team as an exceptionally enthusiastic, caring leader. He is especially proud of the fact that his group works well together, despite the stressors of Covid-19 and despite being from various academic backgrounds, such as forestry, microbiology, medical research, genetics, and environmental sciences. Postdoctoral fellow Dr Kim Martin, for instance, holds a PhD in Biomedical Science from the University of Edinburgh and has worked in tissue engineering projects previously, while technical officer Dr Leandra Moller is a trained microbiologist who completed postdoctoral research in horticulture. These days she gets to work with anything from dataloggers and different types of sensors, such as dendrometers, sap flow sensors and PAR sensors, all to monitor the growth and physiology of trees.

“I think the ability to do anything as long as it falls within the scope of our funder is a highlight. It has allowed us to procure some specialist equipment and to co-fund the setting up of two laboratories that can be used by the whole department,” says Dr Moller.

“The fact that we are from so many diverse backgrounds means that there’s always someone around with the necessary skills to ask for help,” adds Dr Martin.

“The team is made up of individuals from diverse backgrounds, but the bond and teamwork are exceptional. Each time we bring on a new member, they quickly integrate into the team. reveals Oluwaseun Gakenou, who hails from Nigeria and is now pursuing a data-driven research project to model the productivity of certain Eucalyptus species as part of his MSc degree. “It creates an enchanting atmosphere in which your weakness is balanced by another person’s strength. You are not afraid of making mistakes, which speeds up and simplifies the learning process.”


The Hans Merensky Foundation (HMF) is a successor in title to the Hans Merensky Trust, established by Dr Hans Merensky in 1949. According to trustee Chris Pienaar, it is mandated by a constitution, wherein the discovery and support of science in the natural resource arena, represents a primary objective of the mandate.

“As such the HMF finances and support related research chairs at various South African universities and collaborative overseas institutions,” says Pienaar.

Dr Hans Merensky was born on a mission station called Botshabelo, outside Middelburg Mpumalanga in 1871. Without the assistance of modern prospecting technologies but firm in the belief of his visualisation and calculation of the Bushveld Igneous Complex he discovered the platinum group metals reef in 1924. The Merensky reef still carries his name. In addition, he co-discovered gold deposits in the Free State, copper and phosphate deposits in Phalaborwa and alluvial diamonds along the West Coast of South Africa and Namibia.

Being of German descent and confined to his farm during World War 2, he continued to successfully establish commercial, Eucalyptus forestry plantations and leading research-based farming endeavours on his farm Westfalia. It is situated between Tzaneen and Mojadi in the Limpopo Province.

Being involved in mining and minerals for most of his working life and observing the random application of Eucalyptus in mine shafts, he decided to investigate and experiment with higher order applications of this fast-growing hardwood species. The Merensky organisation became pioneers in cultivating and processing Eucalyptus kiln dried timber, applied in the manufacturing and marketing of furniture, doors, and various other industrial applications.

Apart from the higher order economic value of the Eucalyptus tree, Dr Merensky was firm in the belief of the tree’s hydrological qualities. This work continues.

Andrew Morris - big contribution to forestry research

Dr Andrew Morris, who retired from his post as CEO of the Institute for Commercial Forestry Research (ICFR) at the end of March, has had a big impact on the forestry industry in southern Africa in the course of a long and distinguished career.

He has been at the centre of ground-breaking research in Swaziland and South Africa that has played a key role in improving soil quality, plantation productivity and forest health. Imbued with an infectious sense of humour and an irrepressible intellect, Andrew can always be counted on to raise challenging questions and engage in robust debate and exchange of ideas among colleagues and forestry professionals.

After graduating with an Honours degree in Soil Science from Reading University in the UK in 1976, Andrew was employed as a Soil Physicist at the Agriculture Research Centre of the University of Swaziland.

In 1979 he joined the Usutu Pulp Company of Swaziland where he was involved in ground breaking research to explain and correct a yield decline in pine pulpwood plantations. This led to the introduction of fertilizer applications to improve the fertility of the soil, which reversed the productivity decline. This research was the basis for his PhD which he obtained through Reading University in 1987.

On his return to Swaziland, he formed a multidisciplinary research team that developed silviculture research in re-establishment practice, weed control, site-species matching, tree breeding and forest protection, that together with a new site classification realised significant benefits through the introduction of site-specific silvicultural practices.

In 1997 he was appointed General Manager for Research and Nurseries with Sappi Forests based at Tweedie in the KZN midlands. He transferred the concepts of integrated multidisciplinary research used in Swaziland, founded on site classification, across Sappi’s South African plantations. This led to the application of site-specific silviculture practices, and the continued development of tree improvement programmes that delivered improved eucalypt and pine planting stock to the plantations. Propagation research resulted in the modernisation of nursery production to produce the genetically improved rooted cuttings of various hybrids.

The application of this work has had a big impact on the forestry industry with eucalypt wood production per unit area of land significantly increased. Sappi’s eucalypt MAI effectively doubled between 1981 and 2000. Site classification, site-species matching, genetically improved planting stock, application of fertilizer at planting and improved weed control have all played a key role in this productivity improvement.

In a country where the area suitable for commercial wood production is limited with no opportunity for significant expansion, these productivity improvements are crucial in meeting growing demand for wood and wood fibre in South Africa.

Seeking a new challenge to help develop research initiatives beneficial to the whole forestry sector, Andrew joined the ICFR as Research Manager in 2013. His career up to this point had taken him from active research to research management, and the move to the ICFR was intended to reverse this trend. But once again he was required to perform a management role when, from 2017, as Director he led the institute through a major restructure securing new funding for a suite of research projects.

The ICFR Business Manager Karin Nagel took over from Andrew as Acting CEO from 1st April. She has a strong management support team in Julian Chan (Group Leader Tree Breeding), Ilaria Germishuizen (Group Leader Sustainable Production) and Greg Fuller (Technical Support).

“The ICFR continues to provide high quality applied research relevant to policy and practice in the forestry sector which requires continued collaboration with other organisations to deliver the needed multidisciplinary understanding,” concluded Andrew.

Andrew has been an Honorary Professor, Department of Plant and Soil Sciences, University of Pretoria, and Honorary Research Fellow of the University of KwaZulu-Natal. He is author and co-author of more than 35 peer reviewed scientific papers and has presented at numerous scientific conferences, symposia and workshops. He has been involved in several forestry feasibility studies in Africa, South America, China and South East Asia. Industry roles have included Chairman of the Advisory Board for the Camcore International Tree Improvement Cooperative at North Carolina State University (2003-2011), leader of the South African Pitch Canker Control Programme and Editor-in-Chief of Southern Forests: A Journal of Forest Science.

A scientist at heart, Andrew says he is looking forward to continuing his involvement in the forestry industry as a research associate for the ICFR.

“Throughout my career I have been privileged to work with a host of knowledgeable, innovative and motivated researchers, technicians and foresters, and it would be nice to help the next generation in some small way,” he said.

He believes further opportunities exist for investment in forestry research that can bring important improvements to the various forestry value chains important in South Africa, and benefit to the tree farmers who supply the wood.

*Related article: SA researchers push the innovation envelope