Allt y Wern's main feature is the semi-natural broadleaved woodland, but the diversity of habitats make the site important for red kites (Milvus milvus), thin-spiked wood-sedge (Carex strigosa), and mosses and lichens.. The site was managed by coppice-with-standards but the practice lapsed around 1950. Coppice-with-standards is a coppicing method where older trees that have not been coppiced before are felled, opening the tree canopy for new trees, which was an unusual practice in this part of Wales.
