The Government needs to invest more money in looking after publicly-owned woodlands to reverse declines in birds, butterflies and plants, campaigners have said.
Ahead of the publication of an independent report into England's woods prompted by the failed attempt to sell off public forests, the RSPB called on the Government to recognise the value of woods goes beyond timber or land prices.
The public forest estate costs about £20 million a year to the taxpayer but delivers many times that in benefits to people's health, recreation, tourism and natural services, the wildlife charity said.
With woodland wildlife suffering huge declines in recent decades, ensuring public forests are well-managed to help species recover would give the Government a chance to meet international commitments to protect nature.
Last year, ministers launched a bid to transfer ownership of public forests, currently managed by the Forestry Commission, to businesses and charities.
But a huge public outcry forced the Government into a u-turn on the plans, which also suggested communities could buy the woodlands they currently enjoy for free.
Instead, ministers set up an independent panel to assess the future of England's forests, which is delivering its final report this week.
The report is expected to emphasise the importance of maintaining a public forest estate, which currently accounts for just under a fifth of England's wooded area, with a series of recommendations on how best to manage the natural resource.
The Woodland Trust, which ministers mooted as a possible organisation to take over management of "heritage" woods, wants a continuing role for the public estate with the Forestry Commission setting an example on sustainable management of woods and public access and driving forward woodland creation.
The Government should restore 35,000 hectares of ancient woodland that it owns which has been planted over with conifers, the Trust demanded ahead of the publication of the report.
The RSPB wants to see restoration of rare heathland habitat which has been planted with conifers but if returned to its natural state provide homes for rare species including nightjars, sand lizards and Dartford warblers.
Nick Phillips, from the RSPB, said the public forest estate should be managed with a remit to focus on people and wildlife.
The RSPB pointed to Blean Woods, near Canterbury, Kent, which is managed for wildlife including creating areas of heathland which attracts nightjars and coppicing woodland to boost numbers of the endangered heath fritillary butterfly.
The woods, which are owned and managed by a number of organisations, are used by a wide variety of people including parent and toddler groups, runners, dog walkers and walking for health groups.
Mr Phillips said the public outcry over the proposed sell-off had shown how much people valued their forests.
"The Government needs to recognise its value isn't just in land prices and timber," he said, adding the forest estate delivered hundreds of millions of pounds in health and environmental benefits such as storing carbon.
He added: "It's got unprecedented potential, it's the one thing government could easily do to meet key international targets on halting biodiversity loss.
"If you're not doing it there, where are you going to do it?"
He said the amount of money needed to improve management of woods, for example coppicing areas and restoring heathland or ancient woodland, was "peanuts" but could have major benefits for people and wildlife.
"A little bit of Government investment will reward generations, but if they don't do it now heathland and ancient woodland will be lost forever," he warned.
Paul Wilkinson, from The Wildlife Trusts, also said there should be a new focus on nature and benefits for people for England's publicly-owned forests.
"We want to see integration, better protection, reconnection and restoration of woodlands and a new remit for the Forestry Commission.
"There should be a Public Forest Estate with a new purpose, focused on nature, people's connection to nature and the delivery of other public benefits.
"We intend to engage with the Government to ensure any positive recommendations are acted upon, and to strengthen those which may not go far enough for wildlife."