Around 650 hectares of larch affected by or at risk from Phytophthora ramorum have been felled in Afan Forest Park near Port Talbot.
Natural Resources Wales has said the aim is to build a forest more resilient to climate change and potential new diseases, while also increasing biodiversity, improving water quality and reducing flooding.
Its operational resources manager Andy Schofield said: "Like so many of the south Wales forests, this disease has had a significant impact, resulting in the felling of thousands of infected trees.
"However, we are now implementing ambitious long-term plans for the recovery of the forest park which we believe has huge potential to improve the economic and social well-being of the area."
The long term plan for the forest, which covers almost 4,000 hectares, splits the forest into different zones including:
- around 2,000 hectares of conifer and broadleaves for timber production;
- around 1,000 hectares of native broadleaves like oak, aspen, birch and lime;
- around 400 hectares of open habitats for heathland and wetland species;
- around 300 hectares of restored peatland to store carbon and regulate water flows.
Similar long-term plans have been developed for Cwmcarn Forest in Ebbw Vale, where felling work to tackle the disease, which has infected around 150,000 larch trees, will start shortly.
In all, P. ramorum has infected approximately 6.7 million larch trees in Wales, of which Natural Resources Wales has so far felled nearly 3 million. Revenue from sale of the timber is reinvested into the Welsh Government's Woodland Estate.