What is the 3 Billion Tree Pledge?

3 billion trees – a big number, a big promise. As part of the EU Biodiversity Strategy for 2030, the European Union committed to planting 3 billion additional trees by 2030. Without a doubt, trees are incredibly important to our natural environment – they provide crucial roles in various ecosystems, are home to many diverse species, absorb carbon, improve human health and well-being and serve essential roles in flood control and water filtration. This EU pledge plans to do just that. By increasing forest cover in the EU, “in full respect of ecological principles: the right tree species in forests, agricultural areas, urban and peri-urban areas and along infrastructure corridors”. Is this promise too good to be true?

The forest expansion rate in the EU has been slow in recent years, and a goal of 3 billion additional trees would double the total forest expansion rate in Europe between 2005 and 2020. It is currently estimated that in the EU, 300 million trees are grown annually. Currently, as of October 2022, the activity under the pledge has resulted in 6,787,146 new trees have been planted, carried out in all 27 countries with help from 28 organisations such as Land Life and ReforestAction. 

Afforestation – a solution for the biodiversity and climate crisis?

Afforestation and reforestation are not new policies, humans have been planting trees for centuries. There is a consensus that trees and forests are worthwhile and there is a policy to support it. The EU itself has seen the afforestation of approximately one million hectares of agricultural land between 1994-1999, and 700 hectares between 2000 and 2007. Many countries have afforestation policies in place. Canada’s Forest 2020 Plantation Development and Assessment Initiative, not dissimilar to this pledge, saw the plantation of 6000 hectares of forest and its success encouraged the government’s investment of $3.16 billion to plant 2 billion trees in ten years in 2020. Famously, the African Union put in place the Great Green Wall, an ambitious policy to help combat desertification, the AU has been planting a wall of trees to cover 100 million hectares of land and absorbs 250 million tonnes of carbon from the atmosphere. Other approaches have been taken – in 1981, China put in place a law which requires children over the age of 11 to plant a tree per year. 

What is the impact on biodiversity…? 

What does planting trees do? Firstly, forests are important loci for biodiversity, representing often dense ecosystems with diverse plants and animals. Forests are thought to be important habitats, “home to 80% of the world’s biodiversity on land”. Planting more trees in forested areas or reforesting struggling forest ecosystems can have many important impacts. Forests are important habitats and maintaining their integrity through reforestation can ensure that wildlife remains in the region and isn’t forced to relocate. Increased forest density and diversity have also been linked to an increase in species richness for fungi and soil invertebrates. Moreover, tree plantation in urban areas (included in the 3 Billion Trees Pledge) has been studied as a positive act that attracts and shelters wildlife species, particularly birds and insects, and provides shade.

Forests are also key for soil quality and resilience. A lack of trees has been seen to cause a sensibility to soil erosion. Trees’ overlapping and interconnected roots provide a structural role in the topsoil layer of land. This topsoil layer can erode (runoff) without trees in place, which in turn risks the land becoming infertile and inhospitable to the plantation. Moreover, afforestation has been found to improve watersheds, which are key for water supply. 

.. and for the climate?

The benefits don’t stop there – trees can help us in the fight against climate change. Carbon sequestration is a bit of a buzzword in the environmental sphere but it shouldn’t be dismissed. Restoring forests and increasing generally the number of plants on our earth has the potential to absorb and store large amounts of carbon – these are known as carbon sinks. Through photosynthesis, carbon dioxide is absorbed by trees, and they in turn release oxygen. The absorbed carbon is turned to sugar which is used in the wood, branches and roots, meaning that it remains in the standing tree. Even once the tree dies, it takes years for the carbon to break down, apart from when leaves decompose and when carbon is released more quickly. The age of the tree impacts its carbon sequestration aptitude, with middle-aged trees being the most effective and young trees the least effective due to size. Overall, uneven-aged forests are the best at carbon capture – meaning that planting trees in strategic places would allow for uneven-aged forests and increase the potential for carbon sequestration. 

For this reason, afforestation and reforestation are seen as one of the great ‘natural solutions’ for climate mitigation. Policymakers believe these forms of ecosystem services are probable to be of rising importance and relevance due to their impact both for mitigation and adaptation to climate change, and general benefits to our environment. This potential has been recognised internationally with the Paris Agreement emphasising the importance of carbon sinks in order to achieve a balance between emissions and removals. Carbon sinks are a key part of EU environmental policy with recent targets set to increase carbon sinks by 15% compared to today in the land use and forestry sector. 

Overall, the pledge could be very powerful in this regard: 3 billion trees covering 2 million ha could remove up to 4 million tonnes of CO2 from the atmosphere already by 2030, and as much as 15 million tonnes by 2050, according to the European Commission. The decision to encourage tree planting, therefore, seems a logical one, both in terms of benefits for climate and biodiversity.

The right tree, in the right place, for the right reason

However, as with most environmental solutions, it is not as clear-cut as it seems.