Over 140 countries – including the big rainforest nations like Brazil, Indonesia and the Democratic Republic of Congo – agreed at Cop26, the international climate conference that took place in Glasgow in November, to end deforestation. Given that humans have been a net destroyer of forests for millennia, this would be a remarkable shift. Even more tantalisingly, the commitment included a pledge to “reverse forest loss” – in other words, to restore what has already been destroyed. But can we really replace lost plants and ecosystems, or have they gone forever?
Globally, around ten million hectares of forest are chopped down every year, with around 95 per cent taking place in the tropics, according to Oxford University researcher Hannah Ritchie, of Our World in Data. Over a decade, this represents an area of forest the size of Portugal. Reforestation reduces annual net loss to around five million hectares, and most European countries, the US and China, are now net reforesters. However, these nations have already lost most of their old forest cover. Only 5.6 per cent of China’s remaining forest is virgin forest, compared with 41.1 per cent in Brazil.
From a climate perspective this matters greatly, as thousand-year-old trees stock much more carbon than new plantations. The reforestation holy grail would be to reverse accelerating deforestation in the Amazon, and link patches of ancient forest back together to increase the resilience of the “lungs of the Earth”. As it stands, the damage caused by wildfires and deforestation – much of it driven by consumer demand in the Global North – means the Amazon is teetering on the brink of becoming a net emitter of carbon.
From an ecological point of view, the good news is that research published this month shows that deforested tropical forests can bounce back with remarkable speed. If there remains some portion of old forest – whether seed banks, fertile soil or residual trees – the forest can regrow when left untouched by humans for 20 years, to around 80 per cent of old-growth status.
But the problem in much of the Amazon is that land does not serve a purely “natural” function; it is usually owned by people that rely on it for their economic survival. For reforestation to be successful, therefore, the conditions must be right for both people and nature. If communities can make money from more sustainable use of land, they are less likely to chop down trees.
Conservationist Jenny Henman and her charity Plant Your Future works with smallholder farmers to engage in agroforestry in the Amazon in Peru, a country that has to date lost an area of primary rainforest roughly equivalent to the size of Scotland. The charity encourages farmers to grow native timber tree species on deforested lands, in among native fruit tree species like cocoa or Brazilian custard apple, which can be harvested for profit. Over ten years, they have planted more than 80,000 trees. Restored lands have seen monkeys and birdlife return, and better climatic conditions for farming due to the evapotranspiration from replanted trees.
“80,000 trees may sound small, but it is actually pretty big for the Peruvian Amazon,” said Henman. “We often have to persuade families who may have been doing things like cattle ranching for generations. And we have to engage in the whole process ourselves, from harvesting native seeds and growing them in our own nursery, to helping farmers manage the soil and bring back fertility.”
It can take a lot of time and effort before farmers agree to accept outside help, said Henman. After more than a decade of proof about the environmental and economic benefits of agroforestry, “loads of farmers want to join the programme”. Johnson Cerda, an indigenous Quechua farmer from the Ecuadorian Amazon, told the New Statesman at Cop26 that while his community grows crops like plantain and maize on deforested land, it would like to transition to agroforestry, but lacks “the appropriate support”.
Larger organisations engaged in reforestation include the Trillion Trees Partnership. Founded by the WWF, Birdlife International and the Wildlife Conservation Society, it aims to restore one trillion trees globally by 2050. Engagement with local people is crucial, agreed the campaign’s Tim Rayden, a process that begins “years before we even plant the first tree”. And even then, “there have been projects where people have returned to old land-use habits, after which we have to redouble our efforts in community engagement.”
Plantations offer another way for reforestation to deliver economic aid to communities, but instead of bringing broad environmental benefits, these tend to lead to a dramatic loss of wildlife and long-term problems like soil erosion. Data shows plantations of non-native tree species like oil palm and soy are all on the rise across the Amazon. And while countries including Peru, Ecuador and Brazil all pledged in 2011 to restore millions of hectares of forest as a part of the Bonn Challenge, a 2019 assessment published in Nature found nearly half of land covered by the initiative is set to be vast monocultural timber plantations that will be chopped down in one or two decades.
If deforested land covers a large area, and nothing remains of the original flora, recreating rich tropical ecosystems remains a very complex process. “If the forest has been gone for a long time, the top soil gets washed away, and along with it the natural seed bank,” said Rayden. “It then takes heavy-duty landscaping to bring back the forests, and it will take many decades to come anywhere close to how it was, with fire a greater threat because rainfall patterns are no longer so reliable.” Rayden believes the world should continue trying to restore forests, but the significant challenges involved mean that curbing deforestation should always be the priority.
“We are talking about replacing forests that are thousands of years old, that have often been chopped down in just the last few years,” said Alaine Ball, a project coordinator at One Tree Planted, a non-profit that funds reforestation projects. “Often, conditions will allow us to improve the extent and the functional diversity of what remains. But we have to accept that what is gone is gone, and it will probably never be the same again.”