Around 170,000 new, young trees are being planted at Cwmcarn Forest, as Natural Resources Wales (NRW) begins restocking areas which have been felled in recent years.
The new trees have been grown from seeds that were previously collected locally from Abercarn.
They will cover approximately 80 hectares of land across the southern part of the forest and will include a mixture of conifer and native broadleaf.
By planting a mix of different trees, it is hoped that the forest will be more resilient to climate change and disease in the future.
NRW is asking people who use Cwmcarn Forest to help look after the new trees by always closing gates behind them to keep livestock out, and to report any sightings of antisocial behaviour.
The felling operation in Cwmcarn Forest continues as NRW battles to remove over 160,000 larch trees which are infected with Phytophthora Ramorum, or larch disease as it is known.
The Forest Drive remains closed as harvesting operations move into the central northern side of the forest to fell the remaining infected trees.
All other attractions at the site, including the Visitor Centre, mountain bike trails and footpaths remain open, although temporary closures and diversions of trails and paths may be necessary for safety reasons.
This latest phase of work is expected to continue until 2020.
Sally Tansey, regional land manager for NRW said: “We know that Cwmcarn Forest and the Forest Drive is a much loved place and we want to thank local people and visitors for their patience and cooperation as we undertake these important works. We’ve made a lot of progress over the last two years, and we are now taking important steps to secure the future of the forest.
“Cwmcarn remains a popular attraction for walkers, and visitor centre guests and we believe it is a unique site which can offer something for everyone.”