1 The oak tree

Beginning at this mighty oak tree, we can immediately feel the age and stature of this hidden pocket of woodland. Oak trees are a familiar symbol of the British landscape - they have featured in folklore, poetry and art throughout the ages. But this one reveals how there is much more to this ancient woodland than might first meet the eye.

Look closely at the bark. Can you see fine green layers of what looks like a frilly skirt, or even a lung? This is a type of lichen, the aptly named Tree Lungwort. Tree Lungwort likes unpolluted atmospheres with lots of moisture and humidity, and hates acidic environments. Air pollution and acidification mean these lichens have disappeared from much of Britain.  

Lungworts are still found in a very scattered distribution worldwide. In fact some of the lichens, mosses and lungworts found here might also be found as far afield as the Scottish Highlands Tenerife or the Azores – wherever the environment is just right for them to flourish.

The specific habitat requirements of these species make them a great way to understand climate and landscape. The Tree Lungwort here reveals that this slice of woodland is a rare bastion of clean air in a crowded Britain.

This lichen also tells us that this tree is very old. As oak trees age, their bark becomes less acidic. This means the lungwort finds them a more attractive host to grow upon. So lungwort indicates that both this tree and the surrounding woodland are of considerable age.

2 Woodland restoration

Take a breather from the climb through the woodland and peer through the foliage to the right. Can you see a darker patch of forest further uphill?

At first the contrast between those trees and the spot we are standing in might not seem obvious - but there are lots of signs which point to their differences.

Both areas would have originally been oak woodland. Today the darker area is filled with brambles and conifer trees. The Tree Lungwort we saw at the previous stop shows us this is a damp and humid environment. Over 500 plant species are associated with this type of woodland, including 35 regarded as conservation priorities in the UK. But the conifers we can see opposite are not on that extensive list. So why are they there?

Throughout Britain’s history, native trees have been a valuable resource. For centuries the oaks that grew here provided charcoal and building materials for shipping slate from the nearby hillsides. Tannin within oak tree bark was also used for processing leather.

Our strong native yew trees meanwhile were used making longbows from at least the twelfth century. During the attempted invasion by the Spanish Armada (in 1588), trees were planted specifically to build naval ships. As a result there has historically been a fear that supplies of home-grown timber could run out during times of war. 

As the twentieth-century beckoned, an intense period of tree planting began. Straight after the First World War the Forestry Commission was set up with the aim of making us self-sufficient in timber. To provide a more ready and affordable timber supply, swatches of conifers were introduced across Britain.

Conifers are quick-growing, do well in northern latitudes and see a much quicker commercial return than other slower-growing species.  These trees altered the face of British woodland as many ancient forests were cleared to make way for them.

Changing the make-up of the forest like this meant that many of the 500 species associated with oakwood environments perished, paving the way for other species to invade. Virulent rhododendrons took hold beneath new canopies of towering conifers.  The forest canopy became dense and the woodland floor dark.

In 1992 the Woodland Trust acquired the wood we are in now. The Trust has been working on restoring the original oak habitats back to health. On this side you can see where the conifers and invasive rhododendrons have largely been largely removed for oaks to return. Meanwhile the area of conifers across to our right is in the early stage of restoration.

Forest restoration is a delicate process though. Simply eradicating all the conifers would change the woodland’s humidity and remove protection for the more sensitive species, such as the lungwort we saw earlier. Brambles could take hold rather than mosses or heathers, and any young oaks could topple over if all of their shelter were removed in one fell swoop.

So the ideal solution is to gradually ‘thin’ the woodland – remove some conifers and allow the environment to readjust before removing more. See if you can spot younger oaks as we continue up the hill. They are a sign that the original environment is slowly being restored.

3 Old slate barn

This crumbling, moss-covered hut is a relic of the hillside’s working past. This was probably an eighteenth or nineteenth century dwelling used in ‘hafod a hendre’ farming. ‘Haf’ is Welsh for summer and ‘hendre’ is the Welsh for old settlement or farm. In barns like this one the farmers lived under the same roof as their flock. A ‘Hafod’ was a farm on the higher pastures where they would take the sheep during the summer

Another sign of farming is slightly more organised-looking rows of oak trees. These rows may have lined old pasture boundaries. Farming here would have been low impact and minimal, with sheep grazing between the trees on small areas of pasture.

Cleared pastures like this often appear on nineteenth century tithe maps. These maps are a clue to areas of Ancient Woodland. The term ‘Ancient Woodland’ refers to wooded areas in England and Wales dating from 1650 or earlier. Before this date there is little evidence of large-scale farming – and very few reliable maps. So woodland on tithe maps is likely to have been there for centuries, maybe even millennia.  

The clues in the landscape are not always that straight-forward, however. The biggest trees in a forest are often those that grew on open ground with plenty of sunlight and little competition, like the oaks that grew up along field boundaries. But the lack of big old trees doesn’t mean a woodland ecosystem is not ancient - woodland trees may grow slowly or have been cleared over time.

Look out for other indicators, such as woodland flowers or mosses and lichens. These only grow in old woods or the stumps of long-dead oaks. These are clues that Ancient Woodland may live on under the surface in fungi, micro-organisms and invertebrates.  

4 Gate into Llennyrch

We are now on the cusp of change. Behind us is regenerating oak woodland. Across the gate is ‘Llennyrch’, a tract of land that the Woodland Trust has just acquired. Compare the two areas now and you may not notice any major differences. But there used to be some obvious ones.

The land of Llennyrch was never planted with conifers. Instead it had a more consistent history of grazing. It remained relatively open woodland, with bluebells popping up in spring and a mossy layer underfoot. The area is still working farmland today.

Now that it owns the land, the Woodland Trust has built up a strong relationship with the farmer. We can see the results on this side of the gate. Coed Felinrhyd is lightly grazed by the sheep from next door. This, along with the careful reduction in conifers and rhododendrons, has reduced brambles and bracken. As a result rare mosses, lichens and liverworts can thrive.

So, restoring this ancient woodland is not just about removing floral newcomers. The process also involves working with local traditions to support sustainable management of the land.

The Woodland Trust’s newly acquired land goes on up the valley. All of the tracks are permissive paths, so feel free to explore if you would like to lengthen the walk. Just remember how to get back to this gate to complete the trail!

5 Celtic Rainforest canopy

Perched among the dripping canopy, gaze down towards the babbling brook below. Here is where the Celtic Rainforest starts to come alive.

We are only a stone’s throw from a road, yet this spot feels a world apart. And it’s here that the forest’s ancient roots really take hold.

Shaded from direct sunlight and rarely getting a frost, the microclimate here creates the perfect conditions for several rare species. Look closely and you will struggle to find much tree bark without a patchwork crust of lichens or a green haze of moss upon it.

Examples include Blackberries and Custard, which despite the juicy name is fairly unprepossessing.  Barnacle Lichen meanwhile looks like tiny barnacles. Lurking beneath the undergrowth only the keenest of lichenologists might be able to hunt them out.

The steep-sided gorge that tumbles away below us is home to pockets of Wales’ true wilderness. Hazel trees have been harvested for centuries but here, on the slopes of unreachable terrain, it’s likely that they and their associated habitat have remained untouched.

A time capsule of woodland heritage lies right beneath our feet. It’s possible that directly beneath this vantage point the same species have been growing here since the land was first colonised after the last Ice Age – some 10,000 years ago!

6 Tunbridge Filmy Ferns

This unique woodland is not only home to some of Britain’s oldest inhabitants, but some of the smallest and rarest too. Look towards the base of the trees and boulders lining the path. Can you spot flourishes of deep and mottled greens, nestled amongst mosses and tree trunks?

Look for delicate leaves hiding in the undergrowth, like tiny versions of the ferns you may be used to seeing on woodland walks. These are the leaves of the highly localised Tunbridge Filmy Fern. These plants are only found in moist woodland, cloud forests (tropical forests shrouded in cloud) and temperate rainforests. They are rare in Britain – so please do not touch or pick them up.

You can though take a good look. If you have a cheap hand lens or magnifying glass, even better –whole new worlds will open up for botanical exploration. Tunbridge Filmy Ferns are just one cell thick, giving them an almost transparent appearance. When they dry, they change colour.  So keep an eye out for them tucked into the vertical surfaces of rocks or mossy branches.

Having these delicate beauties here, in the same area of woodland as immense ancient oak trees, encapsulates the interconnectedness of the Celtic Rainforest. From the towering forest canopy right down to the smallest species, this woodland’s roots have flourished through the centuries. The oak trees may seem like the age-old symbol of an ancient landscape but what really tells the story of this forest’s age and wisdom is how all of the species live together.

This unique landscape offers a slice of an ancient tropical paradise within the Welsh mountains. And we can be botanists for the day, hunting out the intricacies and minutiae of the plant world.