More than a million acres of woodland could be created in England by letting existing woods regenerate and spread, campaigners have said.
Mapping for Friends of the Earth and Rewilding Britain showed allowing existing woods to self-seed by 150 metres on all sides, excluding important habitats, nature reserves and productive farmland, would hugely boost woodland.
The environmental groups said the findings bolstered calls for the Government to pay more attention to natural regeneration of woods to confront the nature and climate crises, alongside planting more trees.
The charity is launching the Big Climate Fightback campaign, sending more than 700,000 free native saplings to schools and communities to kickstart an autumn tree planting programme, with 680,000 more in the spring.
The calls to boost woodland come ahead of the international Cop26 summit, where countries are under pressure to increase action to avoid the most dangerous impacts of global warming.
The UK Government, as host of the talks, has made trees, forests and natural solutions to climate change one of the key areas to focus on.
Natural regeneration is the process where trees self-seed, through wind-blown dispersal or by animals burying nuts which then germinate, but which can be disrupted by grazing animals.
The Government has announced it will provide grants for natural regeneration but Friends of the Earth and Rewilding Britain say the funding is only for sites within 75 metres of a seed source such as a wood.
Research suggests trees can naturally regenerate up to 150 metres from a seed source, the green groups say, and they are calling for the Government to raise the grant threshold and boost natural regeneration.
He said: “Natural regeneration puts us well on the way to that goal in England.
“By substantially increasing funding for farmers and other landowners so they can set aside suitable land for natural woodland regeneration, we can let nature work its magic.”
Guy Shrubsole, policy and campaigns coordinator at Rewilding Britain, said natural regeneration leads to more diverse woodland, is cheaper than planting saplings and helps make sure the right trees are in the right place.
He added: “This new study confirms that natural regeneration has a huge role to play in helping meet woodland creation goals, draw down carbon and help wildlife to recover.”
The UK is one of Europe’s least wooded countries, with 13% tree cover, and woodland creation in England – mostly through planting – currently at low levels.
Dr Darren Moorcroft, chief executive of the Woodland Trust, which is bidding to establish 50 million new trees by 2025, warned the UK was in a climate and nature crisis.
He warned: “Not only do we not have enough trees, what we have is still at risk and as a result nature has declined steeply.
“While action on biosecurity and woodland loss is largely outside the influence of the public, we can all play a role in increasing tree numbers to help nature recover and tackle the climate crisis.
“The Big Climate Fightback aims to rally the nation to get behind tree planting by finding those underused areas in our communities that could accommodate more trees and make a difference in the fight against climate change and provide a haven for wildlife.”
