I would describe myself as “not the mystical sort”. That means that Diana Beresford-Kroeger’s The Global Forest: 40 Ways Trees Can Save Us is not an obvious book for me. But beyond its mystical side, it also contains a lot of science, and that’s what drew me to it. Particularly, it’s the sort of big picture science that helps you to see the world in new ways.
The author is described in the blurb as “a world expert on how trees connect and effect our environment” and the detailed knowledge and expertise behind the writing is obvious. Yet she puts this into something accessible and highly readable, the inspiration she says in the introduction, the traditional Irish storyteller. So The Global Forest is structured as 40 short essays, which range across key aspects of our global ecosystems, and historical and recent human interactions with them.
The basics are here. This the fact that in the 1950s 30% of global land was covered with forests, and in 2005 that figure was down to something like 5%. Then there is the fact that the demand for paper, almost entirely reliant on trees, has led to exploding demand for pulp of 200 million tonnes a year for the Western world. And the fact that, despite the global garden offering a cornucopia of 80,000 potential food species, we now rely almost exclusively on eight. As the author says: “the traditional knowledge of the other 79,992 is rapidly being lost to future generations”.
And so there are practical suggestions. One of the chief concerns of the book is the promotion of what she calls two-tier agriculture, the combination of tree and ground crops in a “Savannah design”. The chief knowledge base is clearly grounded in North America, and she is fascinating on the subject of the nut crops and the nut milk Native Americans made from them. And also the future potential. “All of the hickory family produces particularly dense wood together with a colossal nut crop…. The hickory can sequester carbon out of the atmosphere like no other tree can. They have done this in the past in vast stretches of virgin forest and they can do it again.”
But the author also ranges widely, and the definition of “forest” is broad.
“In the warmer regions of the world where sun and heat were combined with a source of fresh water, a two-tier agriculture arose that was truly extraordinary. Knowledge of this was extensive in the global garden, stretching from ancient Japan to Lake Chad in Africa into downtown Mexico City. From the stretches of water, fresh fish were netted and sold. Then, as the summer peaked with temperature so did minute blue green algae called Spirulena. These tiny ribbons of blue green cells multiplied into a formidable mass that was rich in nitrogen. This pungent mixture was netted in summer and dried down in the sun. It was then curdled with some form of native plant rennet enzyme, probably from the Malvaceae, commonly known as the mallow family. Then a delicious bread was baked; the flavour and taste is that the most fragrant cheese.”
There’s much practical information to be learned here. I didn’t know that the tender young leaves of the fig tree can be used as a pot herb. And while I knew that dogs often eat grass when feeling ill, I did not know that they were seeking out specifically couch grass, which “in its mature state contains antibiotic”. (Although I will excuse myself for not knowing that hippos seek out tyrosine-rich plants that get converted into two pigmented acids to produce its colourful sweat, which acts as a sunscreen and also an antiseptic that deals with skin wounds. Although I’m glad I do now!) I also did not know that dried ash with water forms potassium hydroxide which is a fertiliser, especially for nut trees. “In addition, a potassium hydroxide solution is a potent fungicide. … The ash creates a high pH surrounding surfaces and acts as an insecticide, keeping populations of pathogens low.”
Not all of the concerns here are practical, however. On the subject of the sex life of what she calls a Chinese diva, Caulokaemferia coenobialis, a tree of which forests, the author enraptured by nature’s astonishing complexity and innovation. (No I’m not going to explain it, I’d recommend reading the book.)
This is a slim highly digestible volume, but with an enormous amount of detail packed into it. If I have one complaint, it is that it really cries out for an index. I’ve had to write my own inside the front cover the facts that I’m sure I will wish to reference.
Yet this is a book that above all shows us how little we know about some critical elements of our world, the basic ecosystems on which we all rely.
What might that mean? Well considered the tale here of the Chamorro people of Guam. Traditionally they feasted once a year on a large flying fox, a bat, Pteropus mariannus. But with the arrival of guns in the Second World War, they were suddenly able to harvest these much more easily, and much regular feasting ensued. But the bats dine on cycads, which contain a “raging neurotoxin”. Many people died. That was despite the fact that the people had regularly dined on cycad nuts, but only in the form of flour, which was washed in many changes of water before cooking, which removed the toxin.
There’s a logic and sense in the way that nature works, and traditional societies and agricultural practices have worked, whether you regard that mystically or not. Reading The Global Forest is a salutory lesson in how little we understand that and how much we rely on it.