Conifer harvesting at Glan Faenol, near Bangor, will eventually allow natural habitat to flourish once again.
The National Trust woodland, which runs alongside the Menai Strait, is a popular walking route that connects Bangor, from Treborth, to Felinheli.
The conifers, which were at the end of their natural life, were suffering from decay and were posing a health and safety risk to visitors.
The National Trust will now gradually replace the conifers with mixed species of various heights and ages, which will provide a much greater biodiversity and opportunities for wildlife.
A spokesperson for the National Trust said: “The National Trust are felling non-native species of conifers at Glan Faenol as they are coming to the end of their natural lifespan, suffering from basal decay and posing a health and safety risk to visitors.
“Our long-term aim is to have a woodland of mixed species of various heights and ages which would provide a much greater biodiversity compared to a monoculture conifer plantation.
“Working with the local community and schools, we will be replanting and encouraging natural regeneration of native broad leaves and expect around 15,000 new trees thus improving the local provenance of the trees in the woodland.
“We will be retaining the mature Scots pine and all the hard woods within the area. These are spread out throughout the woodland, providing a stand of mature habitat trees for wildlife.
“We have been working to improve access at Glan Faenol for many years, which includes improving the footpaths, putting in new viewing points, building a bird hide and aim to establish a community nursery. It’s well used by the local community and a popular site for tourists and will remain open for people to explore.”
