Work has started on felling 20,000 trees at a Ceredigion visitor centre after they became infected with a fungus-like disease.
Larch are being removed at Bwlch Nant yr Arian Forest Visitor Centre, near Aberystwyth, which will remain open.
Natural Resources Wales has replanted around 12,000 native trees at Bwlch Nant yr Arian since the last phase of major tree felling in 2013.
Phytophthora ramorum has infected 6.7 million larch trees in Wales.