The Wildlife Trust of South and West Wales owns and manages the Pengelli Forest National Nature Reserve which is situated south of Cardigan near to the village of Eglwyswrw; there are easy walks near the entrance.
Pengelli Forest is part of the largest block of ancient oak woodland in west Wales; the woodland was owned and described in detail in Elizabethan times by the noted Pembrokeshire historian George Owen. It was once very important to the local economy as a source of timber, and was grazed by livestock that were confined within a bank and ditch. The main body of the wood, with its gently undulating topography and many small streams, has developed on poorly drained boulder clay soils.
Another part of the Reserve, Pant Teg Wood, features steep slopes supporting woodland dominated by sessile oak and birch regrown from clear-felling during 1914-1930. The canopy comprises a mixture of birch, ash and alder with a wide range of hybrid oaks; over much of the site there is a dense understorey of bramble, hazel, honeysuckle, hawthorn and holly. This is the only known location for the midland hawthorn in Pembrokeshire.