The Woodland Trust and National Trust have joined forces for the first time to buy and restore 334 hectares of ancient woodland overplanted with conifers on the edge of Dartmoor in Devon.
Known as Fingle Woods, the site borders two National Trust properties, Castle Drogo and Steps Bridge.
The two organisations aim to restore all the areas planted with conifers to native ancient woodland, in one of the largest ancient woodland restoration projects ever undertaken by either body.
The two also aim to increase public access on the site, with 45km of new footpaths to open by March 2014.
Woodland Trust operations director Norman Starks said: "The best way to restore these woodlands back to their former glory is to change the canopy structure gradually, slowly removing the conifers to let the light back in."
The National Trust's Dartmoor general manager Adrian Colston said: We estimate it will be 50-70 years before this woodland is restored to anything like its former glory, but it will create a protected haven for wildlife and people to enjoy for hundreds of years to come."
A deal has been concluded with the current landowner to buy the wood for £4m, with one-third of the sum coming from the National Trust's own resources.
The Woodland Trust meanwhile has launched a £5m fundraising appeal to help cover its share of the site purchase and meet the cost of restoration over 20 years.