An ancient woodland in south Wales is under threat unless £1m can be raised to buy it and secure its future, according to campaigners.
The forest is home to species ranging from dormice to deer
A total of 352 hectares of Wentwood Forest, near Newport, are up for sale.
The Woodland Trust (Coed Cadw) has already collected £500,000 towards the site's £1.5m asking price.
The trust said Wentwood Forest was the largest ancient wood remaining in Wales, and was home to protected species like the dormouse.
There are also said to be 23 species of native butterfly and 75 species of birds like the lesser spotted woodpecker in the area.
The trust is concerned the site could be purchased by a firm which could carry out commercial forestry in the area.
In 1998, a public appeal was launched to buy 4,000 acres of the southern section of Snowdon in north Wales when it was put on the market.
Actor Sir Anthony Hopkins, who was president of the campaign, famously donated £1m to the appeal, with other contributions coming from Prince Charles and the Stereophonics.
The Woodland Trust said that Wentwood Forest was not as well-known as Snowdon, but was equally important in terms of wildlife and historical value.
"The trust is offering the only hope of survival for this precious habitat," said Sue Holden, the trust's chief executive.
"The ancient woodland is clinging on but we have to act now.
"We need help to support our appeal and to help save this fantastic national treasure house."
The trust has arranged a public meeting to discuss the appeal with the local community at Caerwent village hall on Tuesday night.
Ancient woodland is described as land which has been continuously wooded since 1600 AD in Wales and England or 1750 AD in Scotland.
The Wentwood Forest was once part of a vast area of woodland which ran from the river Usk in south Wales to the Wye Valley.
The Woodland Trust, which was set up in 1972, runs 129 sites in Wales, with a total area of 1,580 hectares.