Dec 4th 2021

A 150-year-old note from Charles Darwin is inspiring a change in the way forests are planted

by Rob MacKenzie and Christine Foyer

Rob MacKenzie is Professor of Atmospheric Science, University of Birmingham

Christine Foyer is Professor of Plant Sciences, University of Birmingham

 

More than 150 years ago Victorian biologist Charles Darwin made a powerful observation: that a mixture of species planted together often grow more strongly than species planted individually.

It has taken a century and a half — ironically about as long as it can take to grow an oak to harvest — and a climate crisis to make policymakers and land owners take Darwin’s idea seriously and apply it to trees.

There is no human technology that can compete with forests for take-up of atmospheric carbon dioxide, and its storage. Darwin’s idea of growing lots of different plants together to increase the overall yield is now being explored by leading academics, who research forests and climate change.

Scientists and policymakers from Australia, Canada, Germany, Italy, Nigeria, Pakistan, Sweden, Switzerland, the UK and the US came together recently to discuss if Darwin’s idea provides a way to plant new forests that absorb and store carbon securely.

Why plant more forests

Planting more forests is a potent tool for mitigating the climate crisis, but forests are like complex machines with millions of parts. Tree planting can cause ecological damage when carried out poorly, particularly if there is no commitment to diversity of planting. Following Darwin’s thinking, there is growing awareness that the best, healthiest forests are ones with the greatest variety of trees - and trees of various ages.

Forests following this model promise to grow two to fourfold more strongly, maximising carbon capture while also maximising resilience to disease outbreaks, rapid climate change and extreme weather.

Images showing how trees grow more strongly when planted in diverse forests.
Images showing how trees grow more strongly when planted in diverse forests, compare the size of the trees at 11-years-old. The trees are oak (left) and larch (right). The tree half-disc on the right of each image was planted in a more diverse area. All trees come from the same estate and were grown under otherwise similar conditions. Author provided

In mixed forests, each species accesses different sources of nutrients from the others, leading to higher yields overall. And those thicker stems are made mostly of carbon.

Mixed forests are also often more resilient to disease by diluting populations of pests and pathogens, organisms that cause disease.

Darwin’s prescient observation is tucked away in chapter four of his 1859 famous book On the Origin of the Species. Studies of this “Darwin effect” has spawned a vast ecological literature. Yet it is still so outside of the mainstream thinking on forestry that, until now, little major funding has been available to prompt use of this technique.

Darwin also famously described evolution by natural selection, a process by which genes evolve to be fit for their environment. Unfortunately for the planet, human-induced environmental change outstrips the evolution of genes for larger, slower reproducing, organisms, like trees.

A man studies an exhibit on Darwin and the history of science at Darwin's home in Kent.
A man studies an exhibit on Charles Darwin and the history of science at Darwin’s home in Kent. Vicky Jirayu/Shutterstock

Modern gene-editing techniques – direct DNA surgery – can help speed things up once careful laboratory work identifies the key genes. But only evolution of human practice – that is, changing what we do – is fast and far-reaching enough to rebalance the carbon cycle and bring us back within safe planetary limits.

Healthier trees capture more carbon

At our meeting we discussed a study of Norbury Park estate in central England, which describes how — using the Darwin effect and other climate-sensitive measures — the estate now captures over 5,000 tonnes of carbon dioxide per year, making it quite possibly the most carbon-negative land in the UK. Such impressive statistics don’t happen by accident or by sticking some trees in the ground and hoping; care and ecological nous is needed.

Trees of different ages also continuously provide harvestable timber and so steady jobs, in stark contrast to the other methods of forestry, where large areas are felled and cleared at the same time.

The UK government, like other administrations, has laid down requirements for responsible large-scale tree planting. These requirements continue to be revised and improved. There are still vital questions about which trees we should plant, where we should plant them, and what to do with them once they’ve grown.

It has been said that it is impossible to plant a forest, but it should certainly be possible to design a plantation that will blossom into a forest for future generations. We need forests to be a practical, dependable, and just response to our climate and biodiversity crises, and Darwin has shown us the way.

 

Rob MacKenzie, Professor of Atmospheric Science, University of Birmingham and Christine Foyer, Professor of Plant Sciences, University of Birmingham

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Browse articles by author

More Essays

A slacker’s guide to climate-friendly gardening
by Aimee Brett
Sep 11th 2023
EXTRACT: "Many people have dipped their toe into the lazy gardener’s life through “no mow May” – a national campaign to encourage people not to mow their lawns until the end of May. But you could opt to extend this practice until much later in the summer for even greater benefits. Allowing your grass to grow longer, and interspersing it with pollen-rich flowers, can benefit many insects – especially bees. Research finds that reducing mowing in urban and suburban environments has a positive effect on the amount and diversity of insects. Your untamed lawn won’t only benefit insects. It will also encourage more birds, such as goldfinches, to use your garden to feed on the seeds of common wildflower species such as dandelions."
The Experimental Shakespeare
by David W. Galenson
Aug 30th 2023
EXTRACT: "Eliot remarked that Shakespeare's greatness not only grew as the writer aged, but that his development became more apparent to the reader as he himself aged: 'No reader of Shakespeare... can fail to recognize, increasingly as he himself grows up, the gradual ripening of Shakespeare's mind.' "
Cat burglers and scammers at large in summer nights
by Michael Johnson
Aug 25th 2023
EXTRACTS: "I moved here 15 years ago from London because it was so safe. Bordeaux was then known as La Belle au Bois Dormant (The Sleeping Beauty). It's the wine capital of France and the site of beautiful 18th century architecture arrayed along the Garonne river." ---- "What’s new is that today lawlessness is spreading into the more comfortable neighborhoods. The favorite technique is to defraud elderly retirees by dressing up as policemen, waterworks inspectors or gas meter readers. False badges including a photo ID are easy to fabricate on a computer printer. Once inside, they scoop up most anything shiny as they tip-toe through the house."
70 years ago, an Anglo-US coup condemned Iran to decades of oppression – but now the people are fighting back
by Simin Fadaee
Aug 20th 2023
EXTRACT: "The 1953 coup d'etat in Iran ushered in a period of exploitation and oppression that has continued – despite a subsequent revolution that led to huge changes – for 70 years. Each year on August 19, the anniversary of the coup, millions of Iranians ask themselves what would have happened if the US and UK had not conspired all those years ago to overthrow Iran’s democratically elected leader."
Painting the Event of Being: Edmundo Bacci at the Peggy Guggenheim Museum in Venice
by Sam Ben-Meir
Aug 18th 2023
EXTRACT: "Edmundo Bacci: Energy and Light, curated by Chiara Bertola, and currently on view at the Peggy Guggenheim Collection in Venice, is the first retrospective of the artist in several decades. Bacci was a native of Venice, a city with a long and illustrious history of painting, going back to Giorgione and Titian, Veronese and Tiepolo. As a painter, he was thoroughly immersed in this great past – as an artist he was determined to transform and remake that tradition in the face of modernity and its vicissitudes, what he called “the expressive crisis of our time.” That he has slipped into obscurity affords us, at the very least, an opportunity to see Bacci’s work essentially for the first time, without the burden of over-determined interpretations or categories."
From Oppenheimer to Milton Friedman: how the Cold War battle of economic ideas shaped our world
by Alan Bollard
Aug 12th 2023
EXTRACT: "Is Oppenheimer a movie for our time, reminding us of the tensions, dangers and conflicts of the old Cold War while a new one threatens to break out? The film certainly chimes with today’s big power conflicts (the US and China), renewed concern about nuclear weapons (Russia’s threats over Ukraine), and current ideological tensions between democratic and autocratic systems. But the Cold War did not just rest on the threat of the bomb. Behind the scientists and generals were many other players, among them the economists, who clashed just as vigorously in their views about how to run postwar economies."
Giordano Bruno, 475 Years Later
by Sam Ben-Meir
Aug 5th 2023
EXTRACT: "I have a modest claim to make: we need Bruno today more than ever. This is because he represents an intellectual antidote to the prevailing ideology of today which tells us that we are doomed to finitude, which comes down politically to the assertion that there is no alternative to the reign of global capitalism. Of course, Bruno did not know about capitalism, globalization or neoliberalism. What he did know however is that humanity is infinite. That we are limited only by our own narrowness of vision."
Vegan diet has just 30% of the environmental impact of a high-meat diet, major study finds
by Michael Clark and Keren Papier
Jul 26th 2023
EXTRACT: "We studied 55,000 people’s dietary data and linked what they ate or drank to five key measures: greenhouse gas emissions, land use, water use, water pollution and biodiversity loss. Our results are now published in Nature Food. We found that vegans have just 30% of the dietary environmental impact of high-meat eaters. The dietary data came from a major study into cancer and nutrition that has been tracking the same people (about 57,000 in total across the UK) for more than two decades."
Improving Art History
by David Galenson
Jul 26th 2023
EXTRACT: "Art historians have never understood economics, and as a result they believe they can ignore markets: in their view, the production of art can be treated in isolation from its sale.  This is of course disastrously wrong.  But their ignorance has led to a neglect of the economic history of art. "
Insatiably Seeking Status 
by R. James Breiding
Jul 13th 2023
EXTRACT: ".....art purchases and prices have plateaued. The prevailing mood at this year’s Art Basel was one of anxiety, as dealers roamed the halls searching for answers. Some speculate that the state of the art market indicates declining confidence among the world’s richest people. When the economy is booming, collectors are more inclined to invest in art and take on leverage, especially when borrowing costs are low. But these dynamics can shift quickly during downturns. The 2008 crisis, for example, caused art prices to fall by 60%."
People with Parkinson’s may benefit from cardio, weight training and yoga – here’s what you need to know
by Aideen Sullivan and Lucy Collins-Stack
Jul 13th 2023
EXTRACT: "But even if you’re having trouble motivating yourself to exercise, many types of physical activity may be helpful as long as you do them regularly. For example, walking, gardening and household chores (such as cooking, hoovering and dusting) may prevent symptoms worsening and improve quality of life. And, these activities may be easier to incorporate into your daily routine than a gym workout."
Why there are fewer insects on UK farms than there were a century ago – and how to restore them
by Simon Potts, Michael Garratt and Tom Breeze
Jul 12th 2023
EXTRACTS: "Insect populations are declining worldwide at a rate of almost 1% per year. This decline is alarming. Insects play a crucial role in pollinating crops, controlling crop pests and maintaining soil fertility. In the UK alone, pollination provided by bees and other insects adds over £600 million to crop production every year. That’s about 10% of the country’s total annual crop value. Through pollination, insects also make sure that fruit and vegetables are packed full of the vitamins and minerals needed for healthy human diets. Insufficient pollination would result in lower-quality foods, less choice and higher food prices." .... "Just like fertiliser and water, these insects should be considered a legitimate agricultural input that needs to be protected and managed sustainably."
Should Rammstein Be Banned? 
by Ian Buruma
Jul 6th 2023
EXTRACT: "But whatever the truth may turn out to be, the Lindemann affair raises a question that has been hotly debated over the past few years, especially in the United States, but more and more in Europe, too: must art be judged by the private behavior of its creator? It has become fairly common for critics to denounce Pablo Picasso’s paintings because he made women in his life suffer. A well-known movie critic declared that he could no longer view Woody Allen’s films in the same way after the director was accused, without any evidence, of abusing his seven-year-old adoptive daughter. Roman Polanski’s movies are no longer distributed in the US, because he drugged and raped a 13-year-old girl in 1977."
How the ancient Greeks kept ruthless narcissists from capturing their democracy – and what modern politics could learn from them
by Steve Taylor
Jun 25th 2023
EXTRACT: "There’s a great deal of research showing that people with negative personality traits, such as narcissism, ruthlessness, amorality or a lack of empathy and conscience, are attracted to high-status roles, including politics. In a representative democracy, therefore, the people who put themselves forward as representatives include a sizeable proportion of people with disordered personalities – people who crave power because of their malevolent traits. And the most disordered and malevolent personalities –the most ruthless and amoral – tend to rise to the highest positions in any political party, and in any government. This is the phenomenon of “pathocracy”, which I discuss at length in my new book DisConnected."
Flavanols are linked to better memory and heart health – here’s what foods you can eat to get these benefits
by Gunter Kuhnle
Jun 11th 2023
EXTRACT: "Although there’s still much we don’t know about flavanols – such as why they have the effect they do on so many aspects of our health – it’s clear from the research we do have that they are very likely beneficial to both memory and heart health."
What Makes the French so Different?
by Michael Johnson
May 4th 2023
EXTRACT: "My recent book on them 25 Unforgettable French Faces covers a wide range of individuals, from an aging Brigitte Bardot to architect Gustave Eiffel. Both of them changed the face of France. In the upcoming sequel, 25 More Unforgettable French Faces, I have completed my collection of 50 examples. The new book, now in progress, ranges from The Bad Boy of the 18th Century (Voltaire) to A Man of Principle (Jean-Paul Sartre) and Big Dark Eyes, (the actress Audrey Tautou)."
Perovskite: new type of solar technology paves the way for abundant, cheap and printable cells
by David Beynon
May 4th 2023
EXTRACT: "Silicon solar cells are an established technology for the generation of electricity from the sun. But they take a lot of energy to produce, are rigid and can be fragile. However, a new class of solar cell is matching their performance. And what’s more, it can now be printed out using special inks and wrapped flexibly around uneven surfaces."
How the brain stops us learning from our mistakes – and what to do about it
by Pragya Agarwal
Apr 21st 2023
EXTRACT: "You learn from your mistakes. At least, most of us have been told so. But science shows that we often fail to learn from past errors. Instead, we are likely to keep repeating the same mistakes." .... "Sometimes we stick with certain behaviour patterns, and repeat our mistakes because of an “ego effect” that compels us to stick with our existing beliefs. We are likely to selectively choose the information structures and feedback that help us protect our egos." ..... "....there are simpler things we can do. One is to become more comfortable with making mistakes. We might think that this is the wrong attitude towards failures, but it is in fact a more positive way forward."
Freeing America from the Quagmire of Inequality
by Sam Ben-Meir
Mar 17th 2023
EXTRACTS: "The intensifying concentration of wealth, and unjustifiable level of income inequality is proving disastrous in many ways. Here are just a few of them. First, less equal societies typically have more unstable economies, and this country is no exception." --- "Second, there is an incontrovertible link between economic inequality and violent crime. The fact is that rates of violence are higher in more unequal societies." --- "Third, the undeniable fact is that the greater the economic inequality that exists, the worse it is for general health outcomes. What is sometimes overlooked is that income inequality is bad for health outcomes across economic strata, not just for those in poverty. To be sure, poor health and poverty are closely linked; but the epidemiological research shows that high levels of economic inequality “negatively affect the health of even the affluent, mainly because… inequality reduces social cohesion, a dynamic that leads to more stress, fear, and insecurity for everyone.” People live longer in countries with lower levels of inequality, as the World Bank reports. In the United States, for example, “average life expectancy is four years shorter than in some of the most equitable countries.” "
Four common misconceptions about quantum physics
by Alessandro Fedrizzi and Mehul Malik
Mar 10th 2023
EDITOR: "Quantum mechanics, the theory which rules the microworld of atoms and particles, certainly has the X factor. Unlike many other areas of physics, it is bizarre and counter-intuitive, which makes it dazzling and intriguing. When the 2022 Nobel prize in physics was awarded to Alain Aspect, John Clauser and Anton Zeilinger for research shedding light on quantum mechanics, it sparked excitement and discussion. But debates about quantum mechanics – be they on chat forums, in the media or in science fiction – can often get muddled thanks to a number of persistent myths and misconceptions. Here are four."