My friend Kirsty chopped down a Spanish chestnut tree. I think it was growing too close to her house. Anyway, she chopped it down and all the nearby chestnut trees started dying. She found out later that she should’ve dug up the roots when she chopped down her tree. Doing this would’ve saved the other Spanish chestnut trees. But why? Why should the death of one chestnut tree impact another growing over 20 metres away? Well the answer is in a book I'm reading.

The Hidden Life of Trees is written by Peter Wohlleben, published in 2016. Peter used to work in the forestry business and he knows a lot about forests. Now he runs an environmentally friendly woodland in Germany and writes about trees and forest ecology. The Hidden Life of Trees is about what trees feel and how they communicate (just like its says on the jacket).

This is what Peter says in his introduction. ‘My story also explains why forests matter on a global scale. Trees are important, but when trees unite to create a fully functioning forest, you really can say that the whole is greater than its parts. Your trees may not function exactly as my trees do, and your forest might look a little different, but the underlying narrative is the same: forests matter at a more fundamental level than most of us realise.’

Prince of Wales Park, Mount Cook, Wellington, New Zealand.

I’m ashamed of my local council. In the middle of the year they scalped an entire hillside of vegetation. Before they did this it looked like the forest that’s visible at the top of the photo (the one above). The forest was a mixture of pines and regenerating native bushes, ferns and trees. I used to go dog walking with a friend through the forest on the hill, back when it was a forest. Now we’re not allowed.

The reason why Wellington City Council scalped a hillside was so they could extend a downhill mountain bike track. The council have put up a sign telling people that It’s too dangerous for them to walk here now. The council have had to spend a lot of money trying to stop all the soil erosion, which has only happened since the trees were chopped down. They’ve also spent a lot of money planting tree seedlings, but they’re a long way off from becoming a forest. Forests take a long time to grow.

Trees are slow compared to us humans. Slow to grow, eat drink and reproduce. They can live a lot longer than we can. The oldest tree in the world is 9,5000 years old. It’s a spruce in Sweden. Our time scale is completely different to those of trees. It sounds obvious, but it’s also the secret to understanding trees and forests.

In July this year during a family cycling holiday I was lucky enough to meet this very old Mulberry tree at a hotel in Shepperton. I seem to remember being told that it’d been planted by King James I. Not by him personally as such, but as a result of one his orders. According to an article I read in The Telegraph, King James I imported 10,000 mulberry trees from Europe. He ordered all landowners to buy and plant mulberry trees. And the reason for this is the mighty silkworm, who, as the name suggests, produce silk. Silkworms only eat mulberries - white ones. France during the 17th century had a monopoly on silk-making and King James I wanted that changed, changed in his favour. Unfortunately he bought black mulberry trees and the silkworms starved. History is is full of these sorts of expensive blunders.

Very old mulberry tree, Shepperton, Surrey, UK.

I haven’t finished the book ‘The Hidden Life of Trees’, but a couple of things really stand out. First, trees communicate (this solves the mystery of the dying chestnut trees). They do this by passing electrical impulses through their tissues, they can taste and smell and feel too. Trees have an extensive root network that connects up with other trees of the same kind. Thanks to an incredible friendship with soil fungi trees are able to communicate with one another. Kirsty’s chestnut tree was connected to all of the surrounding chestnut trees. They communicated with one another using the ‘wood wide web’, as Peter calls it. When Kirsty’s tree was chopped down its roots sent out a message to the other trees and that message caused the other trees to die.

The second interesting piece of information is that trees are social beings. They live in active communities, not just with the same sort of trees but with other trees, plants insects and soil fungi. Again this isn’t new information, that’s what forests are all about. But there are recent studies that reveal startling facts. A tree lives longer in a forest then growing on its own. Trees share food and water with one another and with beneficial fungi and animals. A sick tree is able be kept alive by its neighbours. There are even some tree stumps that are kept alive by the regular delivery of food parcels.

I spent my childhood living beside a forest in Cambridge. A gum forest as it happens. Now I live in a city surrounded by trees. I only have to walk for 10 minutes to get to a forest. Most of the forests in Wellington were chopped down or burnt by early settlers. The trees and bushes growing today are a mixture of exotics and pioneering native species.

Tree ferns in my local forest, Mamaku Cyathea medullaris. — Tree ferns in my local forest, Mamaku *Cyathea medullaris.*

There wasn’t a fence between the forest and my backyard when I was a kid so the forest became an extension of my garden. I thought of the forest as belonging to me. My Dad and uncle built a treehouse for my sister and I, high up between two gum trees. The forest was our playground. There were a group of us local kids who hung out there, building huts, riding our bikes on the dirt paths and pranking anyone who happened to be passing. The forest extended down a gully and joined up with ‘The Bush’, which is what we called the trees, shrubs and ferns that form the native forest in New Zealand.

And talking about ‘The Bush’ reminds me of another book I’m dipping into at the moment.

Mr Cockayne knows how to write!! I have the fourth edition of this book, published in 1967. The first edition was published in 1910. I’m sure some of the botanical names have changed but the general gist of the book is still true.

This is what Mr Cockayne has to say about ‘The Bush’.

‘However little the average New Zealander may know abut the plants of his country, few there are who cannot raise some enthusiasm regarding the “bush”, as the forest is everywhere called. To old and young it is a delight: the stately trees; the birds, fearless of man; and, above all, the wealth of ferns, appeal to all. But that this forest is a unique production of nature, found in no other land, is not a matter of common knowledge, though truely it has many claims to be considered a priceless possession.’

Mr Cockayne is right. Our forests are ‘priceless possessions’ and Peter Wohllebern’s book sets out to prove why this is so.

A photograph of the main street, in Cambridge, taken in the 30s or 40s, showing one of the many oak trees.

There were a lot of English trees planted in Cambridge: sweet chestnuts, horse chestnuts and oaks to name a few. These were popular back when the town of Cambridge was getting established. The oak is one of my favourite trees.

According to Peter Wohlleben oaks are one of the toughest trees around, providing they don’t have any competition. Here’s what he has to say - ‘oaks growing near old farmyards or out in pastures easily live for more than five hundred (years). And what if an oak gets a deep wound or a wide crack in its trunk as a result of lightning strike? That doesn’t matter to an oak, because its wood is permeated with substances that discourage fungi and seemly slow down fungal decomposition. These tannins also scare off most insects and, incidentally and inadvertently, improve the taste of wine - should a barrel ever be made from the tree. (Think ‘oaked’ wine.) Even severely damaged trees with major branches broken off can grow replacement crowns and live for a few hundred years longer.’

One of the things I love about my garden in Wellington is the giant oak tree in the back garden. It reminds me of Cambridge and of being a kid. Oak trees make me think of riding my bike to the park, sitting under the oak tree at school singing Christmas carols and collecting acorns for Mrs Bensemon’s pigs.

Our oak tree has a big crack in one of the main branches. We think it was caused by the wind. It doesn’t seem to have harmed the tee. It’s just as well it’s leafless in winter when we get the worst of the storms.

According to Peter Wohlleben, the suckers sprouting from the base of my oak tree are a bad sign. It’s in distress. ‘They indicate that the tree is engaged in an extended fight to the death, and it is panicking.’ An oak tree shouldn’t be wasting its energy making new branches and leaves down in the gloom at the bottom of its trunk. It’s only doing this because it’s getting harassed. But harassed by what?

In the photograph above you will see a sycamore growing to the right of my oak. I wonder if it’s this tree that’s stealing resources from the oak and stressing it out. Sycamores are opportunists. They’re what Peter Wohlleben calls a pioneering tree species (some would call it a weed tree). It has winged seeds allowing it spread far and wide (oak trees grow from acorns and they don’t fall far the parent tree). Sycamore seeds take root easily and quickly. Before you know it they’ve colonised an area. Maybe the sycamore is a bit of a thug under the soil. For all I know its roots could’ve have taken possession of the back garden: digging its roots into all the friable soil, hogging all the water and nutrients. Given the sycamores procreation method it wouldn’t surprise me if its root system is equally aggressive.

According to Trees & Bushes In Wood & Hedgerow, my oak is a Pedunculate Oak Quercus robur. It is the most common oak. Its bark is smooth when it’s a youngster, but becomes ‘rough, furrowed and rugged’ as it ages. ‘The crown of an oak is composed of crooked branches and is very open, so that a great deal of light passes through. Thus there is sufficient light for various bushes, as well as many grasses and herbs, to grow in an oakwood - a very different picture from the dark beechwoods.’ Or ‘the bush’ for that matter.

A pedunculate oak is called pedunculate because ‘it bears its acorns on long stalks or “peduncles”.

I think an oak tree is the perfect tree for a garden with a bit of space, providing it’s planted in the right spot - with good light and room to grow. A good arborist should keep most neighbours happy. We’ve had a crown lift on our oak and extensive pruning to its southern side (to let in more light for our neighbours). It only blocks sun for half the year, if that. And, as I argued in my last blog, shade is desirable in a garden. There are many plants that grow happily under an oak tree. An oak tree grows slowly and graciously. It provides character, shelter and a sense of scale in a suburban garden. It’s a great tree to climb, tie a swing to, build a treehouse in and picnic under. Birds love big trees. We have many birds who visit, perching in its branches and belting out a few tunes. Oak trees are not a threat to areas where native bush is regenerating, they stay put.

Here’s a marvellous oak tree at the Bolton Street Cemetery dating back to the 1800s. I’ll end with these photos. (Incidentally, I’ll be publishing a special blog during the Christmas break all about the old roses at the Bolton Street Cemetery.)

See you next Sunday.