A species of ancient trees, mostly oak but also beech and ash. Its scarcely present in the UK and Germany as well as in southern Sweden. The loss of such old trees as well as overshading and eutrophication of the bark pose threats to the species.

Germany – Mecklenburg-Western Pomerania, (hist. Lower Saxony)
Sweden – Gotland, Öland, Småland, Skåne, Blekinge, Östergötland, Södermanland
UK – England: Kent, Sussex, Hampshire, Dorset, Berkshire, Somerset, Herefordshire, Derbyshire; Wales: Montgomery, Radnor, Brecon, Carmarthen, Pembrokeshire, Merionydd, Denbigh; Scotland (1960): Berwickshire
Latvia -?

Occurs mainly semi-open or well-lit oaks and beech trees, sometimes on ash and field-maple. The species grows mainly on coarse trunks of ancient trees, often in sites with a long forest continuity. On Gotland, Sweden and the German coast the species occurs in sun-exposed beach sites. In England and Wales it is usually found in parks, pasture woodlands or in open fields and hedgerows.

The loss of ancient trees due to development and/or logging and natural collapse, their shading and overgrowth of semi-open forests is probably a threat. Another major threat is the direct eutrophication of bark by farmyard manure as well as atmospheric pollutants, probably limiting the range of this species. Additionally the widespread die-back of ash in Europe caused by Hymenoscyphus fraxineus reduces the availability of substrate (Ellis et al. 2014).

Because the species occurs usually on single ancient trees, felling these as part of development should absolutely be avoided. At known sites the overshadowing of the bark can be avoided by removing epiphytic climbers and keeping important man-made open habitats like park and hedges bordering pasture land from getting overgrown. Reducing the widespread nitrogen deposition would be beneficial.
It is recognized as a UK BAP Priority Fungi Species (JNCC 2007) with a full plan and listed as a species of international responsibility. In England it is recognized as a species of principal importance for the conservation of biodiversity in England, listed in Section 41 of the Natural Environment and Rural Communities Act. (2006), in Wales as a species of principal importance for the conservation of biodiversity in Wales, listed in Section 42 of the Natural Environment and Rural Communities Act (2006) (Woods & Coppins 2012).
Three of the current seven German locations are situated in protected areas.

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