Can Planting Trees Harm The Planet? It Depends How and Where It’s Done

With an increasing number of businesses and policymakers hailing tree planting as a carbon-cancelling quick fix, conservationist Rose Ellis investigates how to do it right, and why choosing the wrong species or location could actually cause further problems for the planet. 

Trees are absolutely essential to countering the effects of global warming, and our forests are, quite literally, the lungs of the Earth. 

To avoid a 1.5°C global temperature rise we must remove a staggering 730 billion tonnesof carbon dioxide from the atmosphere by the end of this century – a figure that, according to the Intergovernmental Panel for Climate Change (IPCC), will require an additional one billion hectares worth of additional tree cover.

It’s no surprise then, that most of us directly associate planting trees with doing good. With just 2% of the UK remaining as ancient woodland, and deforestation accounting for 10% of global carbon emissions, it’s natural to presume that the more trees we plant, the better. And with many heralding tree planting as the one-size-fits-all answer to the climate crisis, companies and governments too have jumped on the bandwagon. Their pledges look good… but are they?

Part of the attraction of planting trees for companies is that they get some of the best advertising there is. Brands such as Pornhub, which pledged to plant a tree for every 100 videos watched, in turn benefitted from vast amounts of advertising and hype – a marketing team’s dream. Yet all the while it encourages customers that their over-consuming is actually doing something good for the environment, which has all the hallmarks of greenwashing.

In reality, tree planting initiatives might not be quite as good as they first appear. The location, species and management of the tree planting all come into play. One on hand, when researched and executed in the right way as a fundamental part of a company’s corporate social responsibility work, these schemes can fund fantastic organisations such as Trees For Life, which plants and maintains natural forests in Scotland. This offers enormous environmental potential and under good management, protection and careful species selection can provide a wealth of rewards for both nature and humans. 

Images: Dior demonstrates tree planting done right, partnered with Atelier Coloco to source trees that would later be re-planted in wooded areas around Paris. Credit: Dior

Yet trees planted in the wrong place can have worse effects than planting none at all. The dark colour of trees means that they absorb more of the sun’s energy and in colder regions, where snow would ordinarily reflect the sun’s rays, tree cover can result in further warming. The tropics and sub-tropics are some of the best places to plant, as trees near the Equator take up carbon quickly and do not affect the albedo of the surfaceas much. 

The Bonn Challenge – a global effort to bring the world’s deforested and degraded land into restoration – has identified an estimated two billion hectares of land globally that has potential for forest restoration. But it is not always clear if companies are aware of the importance of the location or choose specific sites to plant, instead they tend to focus on number of trees planted.

Choosing the wrong species can also waste all the hard work of planting trees. For example, unsuitable trees planted in China’s arid regions with high levels of evapotranspiration have been found to disrupt and further lower the groundwater and intensify desertification. Experts are calling for water-use efficiency of vegetation to be considered in the future.

The most ecologically productive forests are usually the oldest and most diverse ones. Forests made up of native trees are likely to support greater biodiversity and be healthier, capturing up to 40 times more carbon than plantations. Plantations are areas planted with one species, a monoculture of cash crops, yet they are still considered ‘forest’ under some definitions. While it takes around 70 years for a planted forest to be considered mature, a plantation is likely to be felled each decade, releasing the carbon the trees have stored back into the atmosphere. Unfortunately, this undermines the environmental intent of reforestation and can be misleading.

Images: Trees for Life work to restore wooded areas in rural Scotland. Credit: Trees for Life

So what are the alternatives to tree planting, which still allow us to harness the power of trees? Studies have shown that simply leaving nature to take over an area can be more effective than planting. The experts also found that harrowing to encourage succession and recruitment was enough to trigger sites struggling to naturally regenerate. This is the cheapest and most effective method of forest regeneration, yet of all the Bonn Challenge pledges, only just over one third involve for natural restoration, with Vietnam pledging the most.

There is undeniably merit in tree planting. But there are a number of factors that limit the good. So when we see companies or countries proclaiming sustainability claims through tree planting in the future, we can stop and think – how much good is this actually doing? It is not enough to just plant trees, but rather informed tree planting is paramount. 

As the late ecologist Oliver Rackham was all too aware that “tree planting is not synonymous with conservation”.