Recent high-resolution climate modelling research has revealed that the suitability of key pine species for plantation forestry will shift dramatically by 2060. The lead author, Dr Jaco-Pierre van der Merwe of York Timbers, says these findings are crucial for everyone invested in the future of forests to enable pre-emptive tree breeding and the introduction of new forest species to mitigate climate change.

Pine plantation forests in South Africa are grown in 20- to 30-year cycles, depending on the required final product. Van der Merwe and a cohort of nine forestry specialists from York Timbers, the Institute for Commercial Forestry Research, and universities argue that it is imperative to anticipate future growing conditions to ensure species selection with optimal growth potential.

The challenge is that existing global and regional climate models (GCMs and RCMs) are too coarse for precision forestry applications, and the researchers wanted to develop improved, high-resolution climate projections that incorporate local terrain and microclimatic variations.

In November 2025, Volume 37 of the Journal of Forestry Research published a seminal article by Dr Jaco-Pierre van der Merwe of York Timbers. The title of the paper is: "High-resolution climate downscaling using terrain features and global circulation models: applications for species suitability in the management of plantation forestry."

The Department of Science, Technology and Innovation (DSTI) and Forestry South Africa (FSA) supported the project.

The context

South Africa's plantation forestry sector, primarily located in Mpumalanga, is a significant contributor to the economy, employing around 92,000 people and producing 15 million m³ of roundwood annually.

The sector relies heavily on introduced pine species, notably Pinus elliottii, P. taeda, P. patula, and the hybrid P. patula × P. tecunumanii. These species are matched to sites with climates similar to their native habitats to optimise growth and survival. However, South Africa is a water-scarce country, and climate change is introducing new uncertainties regarding the future viability of these species.

Data and modelling

The researchers referenced climate and terrain data across Mpumalanga and developed models that incorporate climate model outputs and terrain features to predict the mean annual maximum temperature (MAT-max), minimum temperature (MAT-min), and median annual precipitation (MAP-median).

The projected climate change 2020–2060 is:

• Temperature: Both MAT-max and MAT-min are projected to increase, with MAT-max rising by up to 1.7°C and MAT-min by 0.4°C by 2060. Warming is more pronounced at higher altitudes and further from the eastern seaboard (inland regions).
• Rainfall: MAP-median is projected to decrease by up to 10% (125 mm) by 2040, with the most significant reductions in high-rainfall, low-altitude regions (notably the Lowveld escarpment). The rainfall deficit is expected to moderate slightly by 2060.

Species suitability

Pine species were matched to the climate projections to determine whether predicted conditions meet the optimal criteria for each species. The best-performing species in overlapping optimal ranges were prioritised.

• P. patula × P. tecunumanii: Currently the most suitable genotype for the region, thriving in warm, dry conditions. However, its suitable area is projected to decrease by about 9% by 2060, especially in the driest regions.
• P. patula: Area suitable for this species is expected to double (from 4% to 8% of the region) by 2060, as it is well-adapted to the increasingly warm and dry Highveld.
• P. elliottii: Suitability increases in high-rainfall regions that will become warmer, with its suitable area rising from 1% to 2% by 2060.
• P. taeda: Although widely planted today, future climate scenarios indicate it will become unsuitable for the region by 2060.

Implications

What does this mean for precision forestry and plantation management?

Plantation forest growers vitally need accurate tools to assess current conditions and predict future growing conditions, enabling early identification and deployment of alternative species that will be more viable in the future. The researchers urge forest managers to move away from static planting plans.

Although P. taeda is currently widely planted in Mpumalanga, it will not thrive in the projected climate. P. patula × P. tecunumanii, and P. patula should be prioritised for future establishment. Investing in breeding and trialling new genotypes with greater drought and heat tolerance is encouraged.

Van der Merwe et al caution that further research is needed to understand the ability of current and alternative species or genotypes to withstand biotic risks, particularly pest and disease outbreaks, as well as abiotic risks such as frost, wind and forest fires.

They conclude that this knowledge is crucial for ensuring the survival, maintenance and growth of future plantation forests in South Africa and abroad. The models can also potentially be used to research the impacts of climate on the quality of current fibre sources and estimate future implications.

Source: Van der Merwe, JP., van Heerden, E., Germishuizen, I. et al. High-resolution climate downscaling using terrain features and global circulation models: applications for species suitability in the management of plantation forestry. J. For. Res. 37, 3 (2026). https://doi.org/10.1007/s11676-025-01938-4