Twenty million trees will be planted and 2,500 hectares (6,178 acres) of new woodland created in the west of England as part of a “national forest” drive, the government has announced.

The Western Forest will be made up of new and existing woodlands across Gloucestershire, Wiltshire, Somerset, the Cotswolds and the Mendips as well as in urban areas such as Bristol, Swindon and Gloucester.

It will be the first of three new national forests promised by the government to help meet a legally-binding target of achieving 16.5% woodland cover in England by 2050.

However, with only 10% cover achieved so far, environmental groups have warned much more needs to be done to meet tree-planting targets.

The most recent research shows the total area of woodland across the whole of the UK is currently estimated to be 3.28m hectares.

That represents 13% of the total land area of the UK but in England just 10% is woodland.

Across the UK, the aim is for 30,000 hectares of woodland to be planted every year.

The latest annual figures show about 21,000 hectares were planted, with the vast majority in Scotland and just 5,500 hectares in England.

Andy Egan, head of conservation policy at the Woodland Trust, said there had been “significant progress” on tree planting but that there was still “much more to do” to meet the UK’s targets.

He said maintaining government funding was essential.

“Successful tree planting and ongoing management needs long-term grant support,” he said.

“A tough public spending environment could risk undoing much of the good work.”

Alex Stone, chief executive of the Forest of Avon Trust, which leads the partnership behind the Western Forest project, said there were some areas in the region that currently had only 7% of land covered by trees.

“This is about bringing those areas up so we have trees where we really need them,” she said.

“What we are aiming to do with the Western Forest is get to 20% of canopy cover by 2050 and, in five priority areas, we are looking at getting above 30%.”

The scheme will particularly target urban areas, including Bristol, Swindon and Gloucester.

The government said it would be putting £7.5m of public money into the forest over the next five years.

It said the project would not only help the UK’s drive to net zero but would also promote economic growth and create jobs in the region.

Mary Creagh, minister for nature, said she hoped the Western Forest would also “make a huge difference” to water quality, flood resilience and to wildlife as well as bringing nature “closer to people” in the region.

But she conceded there was much more to do in order to hit England’s national tree-planting target.

“I am absolutely confident that we can get to where we need to get to,” she said.

“Projects like this give me hope and confidence that, with everybody pulling together, working with the public sector and the private sector, we can do it.”

She added that, despite ongoing budget cuts, the next two national forests would be delivered by the end of this parliament, with other sources of funding explored.

The Western Forest is the first new national forest to be designated in England in 30 years, following the creation of the original National Forest across Leicestershire, Derbyshire and Staffordshire, where 9.8m trees have been planted.