LookWild: Breathing Life into the Celtic Rainforest

Tucked deep within the valley of Cwm Gwaun lies one of Pembrokeshire Coast National Park’s quiet wonders – a surviving fragment of Celtic rainforest, where clean air surrounds the dense canopy and the trees drip with moss and mystery.

It’s here that a rare and striking lichen – tree lungwort – is being carefully reintroduced, in a bid to restore what was almost lost.

Once common in ancient woodlands, lichens like tree lungwort have become increasingly rare – vanishing silently as traditional land practices changed and air quality declined. Their retreat marked the slow unravelling of a delicate ecological web, where even the smallest losses leave lasting echoes. 

The Lungs of the Rainforest 

Lichens thrive in clean, humid air – clinging to old trees, absorbing rain, and creating microhabitats for woodland insects and mosses. But they depend on balance: the right light, moisture, and bark, all undisturbed by modern pressures. 

One of the rarest is tree lungwort Lobaria pulmonaria, a lichen so iconic it’s often described as the lungs of the rainforest. Its leafy green fronds are surprisingly beautiful, resembling little underwater plants more than crusty tree growth.  

A Lost Fragment Found 

In 2007, only five trees across the entire Cwm Gwaun area were found to host tree lungwort. Then, in 2017, a chance encounter sparked something special. 

After a storm swept through the Sychpant picnic site, a Park Authority Conservation Officer spotted a fallen fragment of tree lungwort on the forest floor. Knowing it wouldn’t survive long where it lay, they acted with quick instinct and quiet ingenuity – using netting from a discarded fruit bag to secure it to the trunk of a nearby ash. 

It worked. Today, that fragment still thrives – and it’s inspired something bigger. As part of the Cysylltu Natur 25×25 project, the Park Authority is now working with a specialist lichenologist to give tree lungwort a fighting chance.  

New Hope Takes Hold 

In a recent transplanting mission, 46 wind-blown fragments of the lichen were attached to 20 trees across three carefully chosen sites in Cwm Gwaun. 

Each tree was carefully chosen through detailed surveys, pinpointing the clean air, companion lichens, and stable bark needed for the transplants to thrive. In addition, every site was mapped and labelled, allowing volunteers to track the lichens as they take hold. 

This is slow work,” says Mary Chadwick, Conservation Officer for Pembrokeshire Coast National Park. “But it’s also hopeful. Tree lungwort is a stunning lichen that embodies the essence of the Atlantic rainforest. We’re helping it find its way back.

The project is funded through the Nature Networks Programme and delivered by The National Lottery Heritage Fund on behalf of the Welsh Government. While the work may be quiet and careful, the impact may be profound. 

If the fragments take hold – and conditions continue to improve – Cwm Gwaun could once again become a sanctuary for lichens lost to time. And it all began with a single storm-blown scrap, a fruit bag, and one Conservation Officer’s quick thinking.  

Sometimes, nature’s biggest comebacks begin with the smallest signs of hope.