This is one of the scarcer woodland types in Wales and is restricted to relatively small fragmented stands in limestone regions.  These woods equate to the Natura 2000 ‘Tilio-Acerion forests of slopes, screes and ravines’ habitat (9180), with the best, and most extensive, examples in the UK found in the Wye Valley.

The Welsh stands of the habitat tend to have a lot of ash (Fraxinus excelsior), small-leaved lime (Tilia cordata), sycamore (Acer pseudoplatanus) and wych elm (Ulmus glabra) in the canopy, though the amount of ash is likely to diminish as a consequence of Chalara infections, with sycamore the most likely beneficiary.   Although not considered native in the UK, sycamore is well-represented in many Welsh stands, as it is in the continental examples of this woodland.