Why are trees so important for net zero?
During lockdown I have felt very lucky that my flat looks out over trees. Watching them changing with the seasons and becoming familiar with the wildlife they support has brought me a sense of calm in these troubled times.
The benefits of spending time in nature, particularly trees have been widely studied. “Tree bathing” has increased in popularity. There are many other positive impacts of trees: they support a wide range of plants and animals, provide timber, their biomass is used as fuel, and they are a carbon store. The carbon is not only stored in the trees themselves but also in a longer-term store in the soil.
However, the UK does not have enough trees. Currently there are 2.9m ha of forest in the UK, covering 12% of land area, this is much lower than the EU average of 37%1. In the UK woodlands currently capture 4% of emissions2. The aim for the UK to have net zero carbon emissions by 20502, means there needs to be both a decrease in carbon emissions and an increase in carbon storage capacity.
The government has pledged that by 2025 30,000 hectares of woodland will be planted each year2. This is at the lower end of the recommendations made by the Committee on Climate Change (30,000 to 50,000 hectares per year)2 but if this target is met and the planting rate is maintained it will be a step towards achieving net zero by 2050.
Zero Carbon Britain suggest that to make our 2050 target the amount of wooded land area in the UK needs to double to 24%1. Land use will have to change to make space for these additional forests. ZCB recommend decreasing meat and dairy consumption so that trees can be grown on land used for pasture and growing livestock feed. This would decrease agricultural carbon emissions while increasing carbon storage. However, not all land is suitable for woodland, peatland, in particular, should be restored and conserved.
Planting trees is not the end of the story, forests need to be managed to ensure they are storing maximum carbon. Currently 59% of woodlands in England are actively managed2. The National Forest Inventory survey revealed that only 9% of woodland is in favourable condition2. Care for woodlands has to increase, to help them to become more resilient to pests, diseases and climate change.
When trees start to decay they release carbon dioxide back into the atmosphere. However, the carbon can be stored for longer if the tree is felled and used as timber. Currently timber frames are used in only 23% of homes in England, however this is much higher in Scotland at 83%2. The UK imports 81% of the timber it uses2, but with more forests, domestic supply will increase, and more forestry jobs will be created. Short rotation forestry and short rotation coppice can be used by farmers to produce a biomass crop. This can be used to produce heat directly, or as biofuel or biogas. The carbon taken up by the tree as it grows offsets that released when the biomass is used as a fuel.
Alongside all these benefits of expanding and harvesting forests there is also the impact they have on our wellbeing. I hope to enjoy many walks in new woodlands soon.
There are several funds to support farmers who wish to increase their woodland. The Nature for Climate Fund is being developed to go alongside ELMS, the government has started a £50m Woodland Carbon Guarantee, and there is UK Woodland Carbon Code.
- Zero Carbon Britain: Rising to the Climate Emergency
- England Tree Consultation, June 2020, DEFRA