Tripling Britain’s temperate rainforest is the goal of a new charity founded by a veteran of the war in Afghanistan who found solace in this unique and biodiverse habitat.

The Thousand Year Trust is being launched this week by Merlin Hanbury-Tenison, who suffered post-traumatic stress disorder (PTSD) after three tours of Afghanistan and is now transforming his 120-hectare (300 acre) hill farm on Bodmin Moor into the largest rainforest restoration project in England and Wales.

The charity is working with local farmers, landowners and charities to identify land suitable to triple Cornwall’s estimated 1,200-1,600 hectares of surviving temperate rainforest, with the ultimate aim of tripling Britain’s surviving rainforest to 1m acres over the next 30 years.

Demands to reintroduce predators such as wolves and bears could significantly damage public support for rewilding the British countryside, a senior conservationist has said.

Francesca Osowska, chief executive of NatureScot, a government conservation agency, said rewilding could only succeed if it won support from people living in and managing the countryside, including farmers and Highland estate managers who are worried about losing their livelihoods.

She said focusing on totemic predators such as wolves risked alienating the people living in rural areas whose involvement is essential if the large-scale restoration programmes needed to address the climate and nature emergencies were to succeed.

Osowska said: “We need to think about rewilding as a much broader concept. We need to think about restoring all of nature, not just large mammals. And that goes from the pine hoverfly to ensuring that we’ve the right mix of forestry – different land types to have that mosaic of habitats.

“The vision I want is of a nature-rich future. Nature-rich means we’re all touched by and living in harmony with nature and able to benefit from it.”

Rewilding 5% of England could create nearly 20,000 jobs in rural communities and increase employment by 50% compared with intensive farming, figures show.

Hybrid roles in animal husbandry and ecology, positions in nature tourism and specialist roles in species reintroductions could be among the new positions, according to analysis from Rewilding Britain, alongside benefits for biodiversity and the climate.

The drive to restore nature on a large scale in the UK’s landscapes has sparked fears of job losses in the agriculture community owing to perceived links to abandoning farmland and halting food production.

But Prof Alastair Driver, the director of Rewilding Britain who put together the figures, said the analysis showed rewilding on marginal land could increase employment without stopping traditional agricultural activities.

“You’re looking at approximately a 50% increase in jobs compared with traditional intensive farming,” Driver said, cautioning that while the figures were positive, there would not be a rewilding industrial revolution.

MPs will have to debate returning vast swathes of land to wildernesses after a petition calling for mass rewilding gained more than 100,000 signatures.

It calls for the government to “make a bold financial and political commitment to nature’s recovery” to help slow climate breakdown.

Expanding habitats for native plants, trees and animals such as beavers and allowing wildlife to return will help remove from the atmosphere the carbon dioxide that is largely driving up global temperatures, organisers Rewilding Britain, said. 

“Rewilding and other natural climate solutions can draw millions of tonnes of CO2 out of the air through restoring and protecting our living systems,” the petition says. 

The group plans to establish at least three pilot projects over the next 10 years, with the aim of returning at least a million hectares to their natural state – twice as much as the land as the government has already pledged to restore.

Last month the government’s own advisers on climate strongly advised ministers to set a new target to bring down Britain’s carbon emissions to zero by 2050.

In a response to the petition before it hit its 100,000 goal, the Department for Environment, Food and Rural Affairs said the government’s 25-year environment plan, launched in January last year, committed the government to improving the condition of the protected sites network and to creating or restoring 500,000 hectares of wildlife-rich habitat in England.  

“Our manifesto committed to planting 11 million trees by 2022, and in addition a further million trees in our towns and cities, and we also have a long-term aspiration to increase woodland cover from 10 per cent to 12 per cent by 2060,” it added.