Spring into action with Plantlife: Ash dieback and lichens notes

Ash Tree along Abberd Brook, Calne

Dave Lamacraft (Plantlife) and Demelza Hyde (National Trust, Lydford Gorge) presented a lecture on Ash dieback and the lichens that rely on them. 

What lichens grow where:

• Climate and microclimate (Light, Temp, Humidity)
• Growth medium (Chemistry, Texture, Porosity)
• Environment (Nutrients, salinity, air pollution)

Elm trees and Dutch elm disease: Orange-fruited elm lichen required elm bark (PH7) and sensitive to pollution. This used to be a quite widely distributed lichen, however it is barely recorded since the 2000s. Similarly Eagle's claws lichen and sap-groove lichen have been hit hard with the loss of Elm. However, sap-groove lichen has faired better due to less Elm-specific requirements.

Why was Elm so important to so many species of lichen?

• pH - alkaline bark
• Rough texture and water retentive bark
• Big, long-lived tree that was widespread
• Tendency to acquire wounds that led to sap runs and wound tracks, which were a niche habitat for lichen.

Ash trees in Britain have over 100 species of lichen associated with them. This includes red list species, which historically were Elm specific species.

• Important for lichen due to being:
• Big, long-lived tree that was widespread
• High pH
• Poor resistance to fungal damage.

We are expecting around 80% loss of Ash in Britain, so what will happen to the lichen species that rely on Ash - what can we do?

Funding by Natural England and National Resources Wales has enabled Plantlife research into ways in which people can manage sites to mitigate impact from loss of Ash. One outcome was the publication: Ash dieback and Lichens in England, which you can download. This short publication looks at the risks and alternative species that could replace Ash as a host. In addition a list of particularly vulnerable lichen are assessed. This document, when followed can help land managers understand how to improve the situation before the Ash is lost - allowing species such as lichen to transfer to the new species or to prosper in dead wood that is left stacked.

We then moved onto a case study at Lydford Gorge, entitled Lichens, Ash Dieback and Lydford: Putting Theory into Practice.

Lydford is an SSSI temperate rainforest on the edge of Dartmoor with over 80,000 visitor each year, with ancient Hazel and Oak woodland on steep slopes. They now know that the 120 acre site is also important for lichens and bryophytes, when Tree Lungwort was discovered around 2019/2020. Since then a Rapid Woodland Assessment and a recording visit from the British Lichen Society has enabled a deeper understanding of the site and much data forming a foundation of knowledge.

Sadly, is has also been discovered that around 320 Ash trees need felling, with many other trees needing work. However, the new understanding has enable Demelza to create a plan for each tree, which has reduced the amount of trees needing to be felled immediately. This is allowing the NT to apply for a translocation licence to enable lichens to be moved to healthy trees.

An action plan was created with Plantlife to understand what the NT could do locally and nationally. This means that the Lydford Gorge team understand the trees that are important to their site and ensuring a favourable environment for those species, such as removing competition.

View the whole talk here: