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Described as ‘small but delightful’ by the British Lichen Society, Cladonia peziziformis, known by it’s common name the Fire Lichen, is a tiny, ground-dwelling lichen, found on just a handful of heathland habitats in South and West Britain. An increasingly rare lichen, it is classed as Critically Endangered in Britain and Near Threatened in Wales.

At less than 1cm tall, with ear-shaped green-grey scales at its base and upright fissured stalks topped with brown fruiting bodies, a hand lens is essential to get a proper look at this miniature, otherworldly species. But the real mystery of Cladonia peziziformis lies in its life cycle.

What do we know about the ‘Fire Lichen’?

A close up of a lichen growing on the ground

In Wales, most records of this lichen are from heathlands within a short distance of the coast, and although these records are well dispersed, ranging from the tip of Anglesey to the Gower Peninsula, the locations where it’s found have an unusual uniting factor.

Cladonia peziziformis only seems to appear in the aftermath of a heath fire, briefly establishing itself on the bare soil, then vanishing once the heath starts to recover. So, what’s going on? Is burning required to create suitable conditions for this species?

One theory is that the nutrients released by plant ash during a burn may play a role in the lichens ecology. Plant-derived smoke also contains multiple chemical compounds which may act as a germination cue, triggering its growth from a spore bank in the soil, though there has been no study to investigate this.

After its initial establishment, it’s thought that Cladonia peziziformis then starts to disappear as it is slowly outcompeted by the recovering heath vegetation.

However, in the last few years, longer-lived populations of Cladonia peziziformis have been discovered in Southern England, occurring on short, heavily grazed less acidic grasslands and heathlands, where localised burning does not always take place.

The fact that this ‘fire lichen’ can be found in habitats which don’t have fires suggests that perhaps its requirement for short open vegetation and bare soil is actually the key factor for its success.

Natur am Byth! answers a burning question…

Two people kneeling in a heathland pointing at a small plant

So, are heathland burns and their associated nutrient and chemical release needed to aid Cladonia peziziformis establishment, or is it the creation of bare ground and short vegetation from fires which benefits the species?

This is what the Natur am Byth! project is trying to find out. Field trials are planned to directly compare the impact of controlled burns vs heathland cutting (to replicate heavy grazing) on C. peziziformis establishment.

Working alongside universities, we will also support lab trials to further investigate the impacts of fire, analysing ash, smoke, and soil nutrient content, and applying smokewater and ash to soil samples containing lichen spores to test for germination cues.

As well as providing training opportunities for students to engage with science and conservation, this research will aid our understanding of heathland fire dynamics, helping to inform future management to support Cladonia peziziformis and wider heathland management in Wales.

The Natur am Byth partnership is Wales’ flagship Green Recovery project. It unites nine environmental charities with Natural Resources Wales (NRW) to deliver the country’s largest natural heritage and outreach programme to save species from extinction and reconnect people to nature. Thanks to players of the National Lottery over £4.1m from the Heritage Fund was awarded to the partnership in June 2023. NRW has contributed £1.7m and the Natur am Byth partners have secured a further £1.4m from Welsh Government, Arts Council of Wales and a number of charitable trusts, foundations and corporate donors. These include donations from the Esmée Fairbairn Foundation, and significant support from Welsh Government’s Landfill Disposals Tax Communities Scheme administered by Wales Council for Voluntary Action (WCVA).

Photo credits: Dave Lamacraft, Eve Grayson, John Spill and Lizzie Wilberforce.

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