With growing international awareness of the urgent need to address the climate change and biodiversity crises, creating forests has become one of the preferred solutions to tackle both issues. Trees absorb carbon dioxide (CO) from the atmosphere and store it in their wood, offering one of the most scalable and cost-effective ways of reducing atmospheric CO2 and helping to reduce global warming. Forests are also critical to global biodiversity, providing homes for most of the planet’s terrestrial animals and forming complex ecosystems, where losing even one species can have profound effects on the others.
Many new forests are planted as part of carbon offsetting projects, which plant trees to absorb the carbon dioxide emissions of businesses and individuals. To date the offsetting projects have mainly focused on planting trees in tropical climates, due to faster growth rates, cheaper labour, and lower land costs. Historically these projects may also have planted fast-growing and possibly non-native tree species (such as eucalyptus), with a focus on planting a specific number of trees, rather than creating biodiverse forests.
Offsetting the emissions for the excessive fossil fuel consumption of rich countries by planting non-native trees at low cost in developing countries has considerable ethical repercussions, however. Given that the UK has one of the lowest levels of forest cover in Europe, that we import most of our timber, and that our native biodiversity is one of the most impoverished in the world, there are compelling reasons for us to invest in restoring forests closer to home.
The Paris Agreement was signed by almost every country in the world and set ambitious goals to limit global warming to 1.5°C by drastically reducing global greenhouse gas emissions every year until 2030. Sea level rises, extreme weather events, reductions in sea ice, and retreating glaciers are already being recorded due to warming global temperatures, and it is critical that the world acts quickly to reduce the carbon emissions that are the primary cause. In spite of increasing awareness of the urgency of the climate crisis and reduced carbon emissions due to the global Coronavirus lockdowns, emissions rebounded post-lockdown and 2020 was the joint hottest year on record. Although new technologies are rapidly being developed to capture excess carbon, or reduce temperatures, planting trees and preserving existing forest remains the most effective, scalable solution to reducing excess carbon dioxide in the atmosphere.
So how much carbon dioxide can forests absorb? Recent research has estimated that forests are currently absorbing a net 7.6 billion tonnes of CO2 per year, which is 1.5 times the annual emissions of the US, around 30% of total global emissions every year. There is great potential for increasing forest cover to absorb even more carbon dioxide, with estimates ranging from an additional 23% of annual global emissions if forests are allowed to regenerate naturally, to 25% of the current carbon dioxide atmospheric pool. Preserving existing forests is critical to reducing atmospheric carbon dioxide, but commercial plantations who harvest timber could also play a key role in increasing the carbon sequestration potential of global forests.
Deforestation rates are still rising, however, in spite of increasing commitments and initiatives to preserve and restore forest. From 2002 to 2020, there was a total of 64.7 million hectares (6.3%) of humid primary forest lost globally according to Global Forest Watch data. In most rich countries forest cover is increasing, but recent research has concluded that rich countries are still exporting their deforestation, just as they are exporting their afforestation (forest creation). It is estimated that individuals in rich countries drive the loss of four trees in tropical countries per year for every individual, primarily due to the consumption of coffee, cocoa, and meat.
Preserving and restoring forests will also help to address one of the other great challenges facing humanity, the global loss of animal and plant species. Animal population sizes have dropped 68% since 1970 and we are losing all species at a faster rate than at any time in the Earth’s history. It is estimated that 1 million species globally are faced with extinction, and there have been drastic reductions in insect populations, which could lead to a collapse of natural systems and considerable problems for food production.
Biodiversity is one of the key terms used to describe the astonishing variety and variability of living organisms on planet Earth, and the complex web of interactions that connects them together. Deforestation is one of the key drivers of biodiversity loss and forest ecosystems are critical to global biodiversity, housing 80% of terrestrial biodiversity, including 75% of bird species and 68% of mammal species. Increasing forest biodiversity can also increase carbon capture, so planting diverse forests provides a dual benefit. Forests also help to reduce soil erosion, reduce local temperatures, assist with water management, and improve our wellbeing.
There have been significant afforestation commitments internationally, from the creation of a ‘Green Wall’ stretching 8,000km across Africa, to an international collaboration in the Middle East to plant 50 billion trees. Brazil has also pledged to stop illegal deforestation by 2030, although there is alarm at the continuing rate of deforestation in the Amazon, which saw the highest deforestation rate of the decade in 2020. The need to preserve and create diverse and thriving forests globally has never been greater.
Most of the climate related afforestation projects have focused on creating new forest in the tropics, where trees grow faster due to warmer temperatures and consistent daylength. Many countries have been quick to commit to planting millions of trees to help tackle the climate crisis but the resulting projects have been dominated by monoculture plantations. Almost half of the Bonn Challenge commitments from international governments are for monoculture plantations of non-native species, with little value for biodiversity or local people, and the potential to increase rather than reduce atmospheric carbon. Although planting in the tropics is critical to tackling climate change and deforestation, recent studies have highlighted the potential for carbon sequestration in boreal and temperate forests, advocating that planting projects do need to be encouraged in these climates too.
Planting trees within the UK forms part of the government’s strategy to reach net-zero carbon emissions by 2050, and they have committed to increasing afforestation rates to at least 30,000 hectares per year starting in 2024. The UK has one of the best track records globally for reducing carbon emissions and the latest target of reducing emissions by 78% by 2035 is the most ambitious in the world. It is estimated by the Climate Change Committee that we will still have 90MtCOe of residual annual emissions by 2050, of which they have calculated that increasing forest cover could absorb 24% (22MtCOe) annually.
However, the UK currently has one of the lowest forest cover rates in Europe, at 13%, compared to a European average of 46% and a global average of 31%. The Climate Change Committee projections are based on increasing this cover to between 17 and 19%, by planting between 30,000 and 50,000 hectares of trees per year. Without additional tree planting the annual forestry net sink is projected to drop from the current estimated 18MtCOe to 8 MtCOe by 2050 due to ageing woodland and low planting rates, which would cause significant problems for our ability to reach net-zero. There is growing concern, however, that the current planting rates are significantly below those required to hit the government targets.
There is a need to restore and plant woodland to increase UK biodiversity as well as for carbon sequestration. The UK has one of the highest levels of biodiversity loss in the world, having lost 50% and ranking 189 out of 218 countries for biodiversity intactness. The species declines are still continuing, with the 2019 State of Nature report recording a 13% decline in average species’ abundance since 1970 and that 15% of species are threatened with extinction from Great Britain. Although the government committed to increasing the proportion of protected land to 30% by 2030, environmental organisations have highlighted how poorly many of our ‘protected’ areas are managed, with minimal benefits for wildlife. In addition, most of the UK’s existing native woodland is considered to be in a poor state due to ineffective management, invasive species, climate change, and disease, with only 7% considered to be in good condition.
There has been a series of recent reports highlighting the importance of woodland to reaching climate and biodiversity targets and the urgent need to create more woodland in the UK, particularly using broadleaf, native species. Reports such as the recent Natural England Carbon Storage and Sequestration by Habitat Report have stressed that it is critical to consider both climate and biodiversity crises when looking at nature-based solutions. A study by the Woodland Trust investigating the state of the UK’s woods also highlighted that planting rates in the UK need to quadruple and focus on native species. Meanwhile Rewilding Britain advocates for the restoration of native woodland to reach 26% tree cover in the UK, mainly through natural regeneration, although this is a slow technique and not effective technique in all habitats.
There are understandable concerns about whether the UK has sufficient space to plant millions more trees. According to in-depth studies by Carbon Brief and Friends of the Earth, converting low-grade agricultural land provides the greatest potential for increasing forest cover. Currently 70% of the UK is farmland and it is hoped that with improving agricultural efficiency and changes in diet, that a proportion of this land could be converted to woodland without increasing our need to import food. Carbon Brief reports that unpublished Forestry Commission data has identified 3.2 million hectares of ‘low sensitive’ areas in England, and 2.7 million hectares in Scotland. It is expected that Scotland would gain the majority share of the UK government’s annual tree planting commitment as there is more low-grade agricultural land.
The Friends of the Earth analysis recommends doubling forest cover in the UK, and although conversion of agricultural land would be a priority, it also states that agroforestry and urban street planting could play a role. Indeed it highlights the possibility of planting on green belt land around cities, which would increase woodland amenities for residents. Both of the analyses conclude that there is space within the UK to meet the tree planting commitments, but that a shortage of manpower and tree nursery capacity could hamper the progress.
One of the critical recommendations insisted upon by scientists is that the existing habitat should be carefully considered before planting begins. This is not only to preserve other rare habitats but also because some habitat types (such as peatland and saltmarsh) sequester more carbon than forest. There have been controversial incidents where new forest has been planned close to areas that are critical for rare ground-nesting birds, or where trees have been planted on wildflower meadows. Experts have also called for consideration of the tree species being planted to encourage native biodiversity to flourish and provide a resilient ecosystem. The mantra often repeated is that it is important to plant ‘the right tree in the right place’.
There are a multitude of additional benefits to increasing woodland in the UK beyond carbon sequestration and increasing biodiversity. Forests provide other ecosystem services such as timber for construction, effective flood defence, soil stabilisation, health and wellbeing benefits for communities, and the potential for nature education.
Increasing forest cover in the UK could be particularly important for the timber industry, as the UK currently imports 81% of its wood products, undoubtedly contributing to less sustainable forestry elsewhere. By contrast, 80% of the wood harvested in the UK is grown to stringent FSC standards. These link into national schemes such as the UK Woodland Assurance Standard and the UK Forestry Standard, which stipulate that every new forestry project must include at least 5% planting of native broadleaves to increase native biodiversity. The carbon locked away in timber can be stored there indefinitely as long as the wood is not burned or left to rot away, meaning that there is considerable scope for the timber used in the construction of buildings to act as a permanent carbon store.
Trees can contribute to flood defence strategies and an Environment Agency study found that trees planted around streams could reduce the height of flooding in towns by 20%. Climate change is leading to increasingly wet winters in the UK with associated flooding, and interest in planting trees to alleviate flooding is growing. Trees help to prevent flooding in a number of ways. The tree canopy slows the rate of water hitting the soil, and then root systems help to channel the water deeper into the soil, slowing run-off from fields and artificial surfaces by up to 80%. Trees can also help to reduce soil erosion and loss of topsoil, further reducing flooding and stabilising slopes without heavy machinery.
In terms of our health and wellbeing, spending time in forests has been shown to reduce stress, improve immune system function, increase concentration, and accelerate rehabilitation following surgery. During lockdowns nature has been critical to wellbeing and it is hoped that the increased interaction with nature will continue, and that people will place more value on preserving our wild spaces. Planting trees in the UK will provide more opportunities to people across the country for interaction with forest ecosystems, encouraging them to protect and invest in nature as well as benefitting personally.
For more details of how Creating Tomorrow’s Forests is restoring diverse, beautiful woodland and other habitats in the UK, please see details of our current planting site in Devon. To join the Creating Tomorrow’s Forests community and contribute to UK based habitat creation, head to our ‘Biodiversity Projects’ page for details of how to sign up.