Woodland dominated by ash (Fraxinus excelsior) and oak (Quercus robur) is the typical woodland of the Welsh and UK lowlands, often growing as relatively small fragments (typically of < 20ha) on deep, fertile brown soils and with ash and/oak dominant in the canopy.   Sycamore (Acer pseudoplatanus), elms (Ulmus spp), beech (Fagus sylvatica) and sweet chestnut (Castanea sativa) have often colonised or been planted.  Bluebells (Hyacynthoides non-scriptus) can provide a blue wash across the field layer on more acidic soils – often with wood anemones (Anemone nemerosa).  On the more base-rich or limestone soils, rarer plants such as herb paris (Paris quadrifolia) can occur.

Thousands of years of management have shaped these woods, particularly through coppicing, which was widely practiced through to mediaeval times.  However, following the industrial revolution, coppicing became uneconomical and many of the woods were abandoned or cleared.  With few of these woods now under active management, the fauna and flora has declined steeply.

However, the future composition of this woodland type is uncertain.  Oaks have struggled to regenerate successfully in canopy gaps for many years and are often replaced by sycamore (Acer pseudoplatanus).  Furthermore, the recent spread of ash die-back (also known as Chalara die-back), through infection by the fungus Hymenoscyphus fraxineus, has had a huge impact on the contribution of ash to the woodland canopies, carrying the threat that many ash trees will be lost to these woods.