A £2.2m project to restore a forest that was left behind after the last Ice Age is due to be launched.
The rainforest nature of the woods gives them their biodiversity
The 58 woodlands of Atlantic oak in Meirionnydd are home to more than 1,000 native species of flora.
They were once part of the forest on the Atlantic coasts stretching from northern Scotland to Portugal.
More than 4,000 acres of the woodlands will be looked after in a project aimed at restoring some of the character first created 14,000 years ago.
The woodlands are considered to be some of the best areas of Atlantic oak woodland in Europe and have been designated as candidate Special Areas of Conservation because they are endangered or vulnerable.
Lea Hughes, Education Ranger for The Meirionnydd Oakwoods Habitat Management Project, said: "If you just take a minute and look around, you'll just see that there are hundreds and hundreds of different species.
"There are prehistoric plants here. All these mosses and lichens are basically prototype plants and the first plants to develop after the last ice age.
"We're really lucky that we have them here to look at today."
Half the money for the four-year habitat scheme is from European Objective One funding schemes.
The rest of the money has been raised by the woodlands' public and private landowners and the bodies supporting the scheme.
Partner organisations include the Forestry Commission, the Countryside Council for Wales, Flintshire Woodlands, the Woodland Trust, Ffestiniog Railway, the National Trust and Snowdonia National Park Authority.
The work, to promote the importance of the woodlands to the local community, their visitors, the economy and the environment, should support the equivalent of 72 full-time jobs.
The project is launched on Friday by Lord Dafydd Elis-Thomas, the Welsh assembly's Presiding Officer.