Commercial Forestry for the Climate?

Introduction

Woodland covers just 13% of the total land area in the UK (Forest Research, 2021), compared to a European average of 44%, meaning potential for afforestation in the UK is high (Lamb et al., 2016). With ambitious planting targets of 30,000 hectares of new woodland each year forming a central pillar in the government strategy to reach net zero emissions by 2050, it is imperative that the UK forestry sector adopts an environmentally conscientious approach to tree planting.

Tree planting in the UK comes in a variety of forms. Commercial forest plantations (Figure 1a) typically describe woodland creation schemes with fast-growing, non-native species such as Sitka Spruce (Picea sitchensis) which are eventually felled to produce a range of products including sawn timber, fencing, wood fuel as well as to efficiently sequester carbon. Conservation forestry (i.e., unharvested woodland) is the practise of planting and maintaining native forests (Figure 1b) with the principal focuses being on improving local biodiversity, creating spaces for recreation, and protecting natural resources.

So which approach is best for the environment? Often the perception of cutting down trees in commercial forestry is wholly negative. Ongoing media coverage of the catastrophic deforestation of tropical forests leaves many with the understanding that tree felling is bad for the planet (Forest Research, 2021). Given the range of benefits delivered by conservation forestry, many people are left to conclude that conservation forestry is the only way forward to tackle the ongoing environmental crisis. Furthermore, in tropical regions, wood production has been unfavourably compared to restoration of natural forest (Lewis et al., 2019) as the benefits of supporting local economies are far outweighed by long-term carbon sequestration in natural (unharvested forests).

However, these conclusions are not necessarily transferable to a temperate context (Forster et al., 2021). The UK forestry industry is highly regulated, and all forestry must follow the UK Forestry Standard (UKFS). Recent studies astutely argue that long-term (90 years +) conscientious management of commercial woodlands in the UK can be more effective climate change mitigation strategy than planting conservation forests.

The Evidence

In a recent study by Forster et al. (2021), the GHG mitigation potential of commercial forestry was compared to that of conservation (i.e., unharvested) forestry practises. Assuming planting at a rate of 30,000ha per year in line with government planting targets, the research team used dynamic consequential modelling of a range of scenarios with varying conifer-broadleaf composition, harvesting, product breakouts, decarbonisation and substituted energy, and materials, to estimate 100-year GHG mitigation.

Despite harvested commercial forests storing 61% less terrestrial carbon than unharvested conifer forests and 42% less than mixed conservation forests, this is more than offset by GHG emissions mitigated through hard wood production carbon storage, concrete and fossil fuel substitution and bioenergy carbon capture and storage – Figure 2.

Figure 2: Images of where commercial forestry can help to mitigate carbon emissions. a) HWP carbon storage, b) concrete substitution, c) fossil fuel substitution and d) bioenergy CCS.

The results of the study show that newly planted commercial forests (short rotations, ~ 50 years) could achieve GHG mitigation of 2270 tonnes CO₂e/ha in the UK by 2120. This is up to 269% more than delivered by newly planted broadleaf conservation forests and 17% more than unharvested conifer forests. The results are shown in Figure 3.

Figure 3: A comparative bar chart showing the relative mass of CO₂e removed from the atmosphere from various commercial and conservation forest scenarios. Core and FA (Further Ambition) refer to differing decarbonisation contexts – see Forester et al. (2021) for more details.

In addition to long-term GHG mitigation, commercial afforestation can provide the following benefits:

Reduced risk of fire
Safeguard of carbon stocks in HWPs
Reliable growth of trees on marginal land
Higher carbon yield that draws more investment into woodland creation

The Future

Whilst the study demonstrates the environmental benefits of commercial afforestation, it is important to note that this can cause trade-offs with other ecosystem services, for example biodiversity (e.g., Chisholm, 2010). The FCF use a complex and scientific set of woodland design metrics that can be used to balance the benefits of commercial afforestation with those of conservation forestry in Canopy schemes.

Commercial forest lags unharvested conservation forests in terms of GHG mitigation for much of the 100-year period modelled which stresses the importance of long-term management. FCF requires all Canopy projects to be managed long-term by industry experts.

Reference List:

Chisholm, R.A., 2010. Trade-offs between ecosystem services: water and carbon in a biodiversity hotspot. Ecological Economics, 69(10), pp.1973-1987.

Forest Research. 2021. Resources: Forestry for Woodfuel and Timber. Available at: https://www.forestresearch.gov.uk/tools-and-resources/fthr/biomass-energy-resources/fuel/woodfuel-production-and-supply/woodfuel-production/forestry-for-woodfuel-and-timber/ . (Accessed 21/09/21)

Forest Research. 2021. Resources: Woodland Statistics. Available at: https://www.forestresearch.gov.uk/tools-and-resources/statistics/statistics-by-topic/woodland-statistics/ (accessed 20/09/21).

Forster, E.J., Healey, J.R., Dymond, C. and Styles, D., 2021. Commercial afforestation can deliver effective climate change mitigation under multiple decarbonisation pathways. Nature Communications, 12(1), pp.1-12.

Lamb, A., Green, R., Bateman, I., Broadmeadow, M., Bruce, T., Burney, J., Carey, P., Chadwick, D., Crane, E., Field, R. and Goulding, K., 2016. The potential for land sparing to offset greenhouse gas emissions from agriculture. Nature Climate Change, 6(5), pp.488-492.