To plant or not to plant: trees

Photo credit: Cosmo Robertson Charlton

Cosmo Robertson Charlton is a final year student studying zoology at the University of Bristol. Although currently based in Bristol, he has strong connections with Sussex as Lewes is his home town. He has a keen appreciation for the natural world, being particularly interested in conservation, rewilding and positive solutions for climate change. He is currently a member of the Youth Council as part of the United Nations Association for Climate and Oceans, organising events and empowering young voices in the fight against our climate crisis.

Trees are often considered the silver bullet in our fight against global warming. The public rhetoric is generally ‘the more the merrier’, with planting initiatives popping up all over the globe. However, could this tree-topia we all dream of be a misguided venture? Recent research has indicated a need for careful consideration when we plant and has called for a more nuanced approach.

Carbon sequestration is the process of capturing and storing atmospheric carbon dioxide. Forests and woodlands alike are well-known for their ability to sequester carbon, and tree planting has therefore been hailed as a solution for combatting climate change. In theory, this makes complete sense. After all, the more carbon dioxide we can remove from the atmosphere the better, right? 

Unfortunately, it just isn’t that simple. Where we plant trees, or allow trees to grow, needs careful consideration. Trees in the northern hemisphere can absorb almost twice as much of the sun’s radiation in comparison to grassland, contributing to rising global temperatures. In Siberia, this information has led some scientists to recommend that herbivores manage grasslands. Not only do herbivores feed on saplings, reducing tree cover, but they also compact permafrost. This prevents thawing, which in turn, increases the amount of radiation reflected back out of our atmosphere, as well as slowing the release of carbon dioxide from permafrost soils

Photo credit: Justus Menke on Unsplash

Policies aimed at increasing tree cover have been used by governments globally. In Chile, the government subsidised 75% of the cost of planting forests by private landowners. However, due to lax enforcement, old forests were cut down to accommodate new, more profitable monoculture plantations. Not only does this harm biodiversity, but when it comes to trees, size matters: one seminal study found that carbon accumulation by a tree increases continuously with size. If not adequately enforced, financial incentives are always vulnerable to exploitation. 

Tree planting schemes have the advantage of attracting support from across the political spectrum. The former president of the United States, Donald Trump, got right behind the Trillion Trees Campaign – a global campaign to conserve 1 trillion trees – despite his many disparaging statements about our climate crisis, calling climate change a ‘hoax’. It’s easy to see why so many political leaders have jumped on the tree planting bandwagon as part of their manifesto. It’s a relatively cheap and easy way to appease their climate-conscious supporters. After all, any environmental scheme endorsed by Donald Trump is surely worthy of scepticism.

Large corporations have followed suite, ‘greenwashing’ consumers into thinking they are environmentally friendly and therefore acceptable to support. 

The aim of this article is not to condemn tree planting. Done correctly, it can be an incredibly valuable method to slow the effects of global warming. The way in which we plant and manage our forests must, however, be planned with greater thought.

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Perhaps other carbon sequestering organisms are equally worthy of our protection, such as marine algae. Per acre, these underwater forests may take up 20 times more carbon dioxide from our atmosphere than their land-based counterparts, although there is still a lot we don’t know about their carbon capture. Some have called for better conservation of these underwater forests, with stricter regulations on deep sea trawlers which rip these underwater forests to shreds, thereby unleashing their store of carbon dioxide. 

Marine algae also grow at a far faster rate than land forests. For example, kelp can grow 2 feet per day. Theoretically, we could create vast kelp forests underwater to capture atmospheric carbon dioxide. We must broaden our attention from the terrestrial forests we can see to the underwater jungles we can’t, which are so dangerously hidden from sight and mind.

Boat on clear water with kelp under the surface
Photo credit: Pahala Basuki on Unsplash

Our coastline in Sussex, and especially West Sussex, was once protected from the pounding waves by a thriving kelp forest. Since the intensification of fishing, this forest has been all but destroyed by trawlers raking their metal nets along the sea floor. Help Our Kelp is a Sussex Wildlife Trust project which aims to restore our once lush underwater forest through a 300-kilometre protection zone in which trawling is largely prohibited. The fast-growing nature of kelp means, given time and space, it could grow back far more quickly than any terrestrial forest. In addition to carbon sequestration, this kelp forest would provide a valuable habitat for hundreds of marine species. Sir David Attenborough has described it as “a vital win in the fight against the biodiversity and climate crises”. 

In short, tree planting is not some ‘golden ticket’, but merely one piece of a jigsaw puzzle. Fitted in the right place and as part of a more holistic approach, including management and protection of aquatic forests, it could indeed help us slow the rate of climate change. We must be more conscious of where we plant our trees, and even why we are planting them. 

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