Roots: On the power of trails and the majesty of ancient trees

Over Christmas I returned to my childhood home of Hexham, an old market town that sits above the south banks of the River Tyne. The Tyne Valley is a patchwork of farm, woodland, and moors, bisected by innumerable burns and streams that feed the North and South Tyne. The two converge at Waters Meet to form the River Tyne, which then winds its way to Tynemouth and flows into the North Sea. To the north of the valley lies the Great Whin Sill, atop which sits Hadrian’s Wall, and beyond that the Northumbrian Fells of border country. In the south, the northernmost tip of the Pennines, the backbone of northern England that runs right down to the Peak District. I joined my mum’s support bubble when I came back, and we’ve taken great pleasure in exploring this fascinating landscape, with all its hidden denes and woodlands. Though the lockdown has restricted our walks to a smaller radius, we — and many others — are slowly rediscovering the lesser walked trails of the more immediate vicinity.

The valley streams make for prime dipper habitat

On a recent excursion we traced the path of a walk I have done many times over the years. This time we took a small detour through a neighbouring field. To my delight, the field concealed a small stream, which on this frosty winter's afternoon was running vigorously. We weren't lucky enough to see any dippers scouring the bottom for insects, but this certainly would have been prime real estate. Away from the stream we came upon a grand old oak. Perhaps once part of an old hedgerow, the tree now stood in a sparse line of other stoic giants. And the tree’s immense age was clear. Thick limbs and branches twisted and sheered from three main forks, dividing further and further until reaching barren buds. A mosaic of wood — some parts alive, some parts dead, other parts somewhere in between.

And on this crisp late January day when the sun, hanging ever so slightly higher in the sky, felt warm for the first time, the oak was alive. We stood and watched, for 15 minutes or more, passing between us our single pair of binoculars. Nuthatches and treecreepers roved the flaking bark for invertebrates. A band of long-tailed tits passed in their jolly council. Blue tits, great tits, coal tits, wood pigeons, robins, blackbirds, assorted corvids, a low flying buzzard. There was birdsong in the air, at last. It was like the world had suddenly woken up.

The grand old oak in all its glory

A tree can tell a story. As it lives, grows, ages, new domains arise from the decay. Flakes of bark peel, pools of water form, limbs hollow. Rare specialist fungi establish, helping to decompose old wood and return the nutrients to the soil. A dizzying diversity of lichens continue their slow conquest, growing less than a centimetre every decade. With the rich variety of resources and micro-habitats, ancient trees make the ideal home for a vast array of remarkable invertebrates. On a single oak tree you might find up to a thousand different species. Ants, bees, beetles, flies, mites, ticks, and wasps — they all have a niche. Some eat the fungi or lichen. Others eat each other. Many eat the wood itself, with the help of specialised gut microbes that break down cellulose and lignin, the components of wood. It’s a fair living.

A woodland can tell a story, too. Our old-growth forests have existed for hundreds of years, a stable environment where deep evolutionary bonds have been allowed to root. There is a distinct set of rare, ecologically important invertebrates whose lives are so entwined with ancient woodland that their presence is used to determine the quality and continuity of a habitat, using what’s called the Index of Ecological Continuity. They are the very definition of old-growth. When a site contains a lot of these species, it’s likely those trees have been there for hundreds of years.

The deep connection between invertebrates and trees is what makes ancient woodlands such a unique place, full to the brim of fascinating and important wildlife. But this dependence makes them vulnerable. Wood beetles are a key food source for small mammals, and birds like nuthatches and treecreepers. However, they require lots of dead or decaying wood to survive, and some species will only lay eggs in mould-containing hollows that develop after centuries have passed. Those beetles and many other invertebrate species need the wood-decay cycles only found in old-growth forests. But humanity’s vice is tightening.

A snowy south bank of the River Tyne

According to the Woodland Trust, 800 ancient woods have suffered loss or damage from development since 1999, and 1000 are currently under threat, largely from substantial road and rail infrastructure projects, such as HS2, which plans to barrel unfettered through 61 ancient woodland sites. The project promises to plant 7 million trees as recompense, but only 10% of those seedlings might make it to fully fledged tree status 50 years from now — assuming they are well looked after. It is clear that no amount of tree planting can replace the complex, valuable, ancient woodland habitats that provide a home to swathes of wildlife, and a refuge for the people lucky enough to live near them.

Ancient woodland losses are devastating invertebrates, in a pattern that is being repeated in every habitat, on every continent, across the globe. Scientists have described it as ‘death by 1,000 cuts’, as human existence pushes insects ever closer to the edge. Logging, development, pollution, urbanisation, tourism, agriculture, disease. At the current rate of loss, most species could disappear over the course of the next century. And the importance of invertebrates should not be understated. They are the structural and functional base of the world’s ecosystems, vital for nutrient cycles, seed dispersal, pollination, soil health, water purification, biological control of pests — the list goes on. Healthy invertebrate populations support healthy ecosystems. Healthy ecosystems provide ecosystem services — our life-support. We cannot live without them.

In nine months the UK hosts COP26, the UN Climate Change Conference in Glasgow. In attendance will be the 197 countries that signed the 1994 climate change treaty, which binds them to cutting dangerous levels of emissions. They will review progress made on the 2015 Paris Agreement, which aims to limit the global temperature increase to 1.5C or less, and inspect each nation’s carbon reduction plans made since COP25 in Madrid. This is probably the most important climate summit of our generation, as we emerge from the pandemic into a decade where governments must take immediate and decisive action to avoid catastrophic climate change.

With COP26 on the horizon it is vital the UK sends a clear message about leading the world to a cleaner, brighter future. We need to take action to save nature, to save earth, to save ourselves, from the climate and biodiversity crises racing towards us at full speed. And we can start with our ancient oaks.

Thank you for reading! For references click here. If you're a data nerd like me, there's a huge open-access database of all the species associated with oak trees that you might enjoy playing around with.