Wentwood Forest: Larch disease felling in ancient woodland
4 October 2013 Last updated at 20:53 BST
The felling of diseased trees across an area the size of around 300 football pitches is taking place at Wales' largest ancient woodland.
Larch trees at Wentwood Forest, near Newport, have become infected with the fungal disease Phytophthora ramorum.
The infection can kill trees and has spread across the UK after being found in south west England four years ago.
The Woodland Trust, which owns most of the forest, said the felling of the trees was essential.
Paul Heaney reports.