Book of the Week: How to Read a Tree

Trees are keen to tell us so much, says Tristan Gooley. They tell us about the land, the water, the people, the animals, the weather and time. But only to those who know how to read them

The urban environment is tough for trees, with heavy footfall and motor traffic, but there are less obvious stresses too. It is warmer and drier than the surrounding area; there may be de-icing salt, dog mess and a long queue of people wanting to dig up the world.

The London plane has been planted in towns and cities around the world because its roots tolerate compaction of the soil and its bark sheds regularly, allowing it to withstand more pollution than many. The sycamore is a member of the maple family that copes well with the stresses of town life, too well perhaps: it has a reputation for sprouting up uninvited in gardens and parks.

I once visited the coastal Devon town of Budleigh Salterton to give a talk in a church. I parked the car and ventured out to find the venue, but all I could remember was the name of the church and the part of town it was in. I ran around looking for yews, discovered some lining a residential street, then peered through a gap and found the venue just in time. Yews have been planted for centuries in many churchyards and other significant sites in towns. (In rural areas, yews are a sign of few grazing animals as their toxicity means the two don’t mix.)

Trees don’t form straight rows in natural environments. Even those that line a river will show curves that reflect the bends. It follows that any straight line of trees is a sign that humans are behind it. The most obvious are the formal avenues of trees leading to something grand at the end, but there are many more interesting examples.

Lombardy poplars are often planted in a line that marks the edge of a property, village or farm. They are so easy to recognise once you know them, standing taller than the other trees in the landscape, with thin branches that reach for the sky. With practice it becomes instinctive to spot their forms, and I regularly use them to identify the location of a hidden village. The Lombardy is a member of the water-loving poplar family, so it is often a double clue: civilisation next to water.

It is so satisfying when we connect the dots in a landscape. The other day I set myself the challenge of descending a Sussex hill and finding a village, using only the trees for guidance. At the foothills of the northern scarp, I found ashes thriving in the rich, moist soil; a little further on willows lined a stream. The water led me to the village, and I knew I had arrived when the horizon was broken by a proud line of Lombardy poplars.

All plants are sensitive to disturbance. If the land is ravaged by storms, fire, water, human clearance or heavy use, certain trees give up on it for long periods, while others are happy to start again as soon as the drama is over. The following families are keen colonisers, springing up in disturbed areas – if you see lots of young ones, it is a sign of a major disturbance: willows, alders, larches, birches, hawthorns.

All of these trees are pioneers, the hares, winning in the short run, but most will be gone within a century, having been replaced by the climax tortoises. This means they form a particular sort of map. They hint at motion and upheaval and tell us of a recent major change in the landscape. We should look for the cause.

Larches are colonising conifers and look quite different from most other conifers throughout the seasons. They have distinctive paler foliage in summer and, unusually for conifers, they are deciduous, losing their needles in winter. Larches spring up in places where humans try to cut ribbons through the trees and make a useful map, marking regularly used forestry tracks through coniferous woodland. Look from a local peak and you will see their pale lines snaking through the darker trees, marking well-worn vehicle tracks. Often you can spot a bigger clump of larches surrounding a depot or a spot where forestry work is going on.

In areas that are prone to wildfires, a different type of competition is taking place. No trees find fire easy, but some have evolved to endure it better than others and tend, over time, to out-compete the vulnerable. For example, the Douglas fir sees off most of the competition in the fire-prone regions of the Pacific Northwest.

There are interesting patterns on the charred trunks of pines on many wild, mountainous landscapes. In places like La Palma, in the Canary Islands, the trees are tough, coping with dry, rocky terrain and altitude, as well as being fire-resistant. As a wildfire moves through the trees, it will char and scar one side more than another. If you take the time to note the darker sides of the pines, this consistent trend can act as a compass for natural navigation.

This is an extract from How to Read a Tree: Clues & Patterns from Roots to Leaves by Tristan Gooley (Hodder & Stoughton)

We’ll be chatting to Tristan Gooley on “A Drink with the Idler”, Thursday 4 May at 6pm London time. Book your tickets here. Free to Idler magazine and Academy subscribers.