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Can tree planting solve climate change?

1 juillet 2020

Can tree planting solve climate change?

Tree planting schemes have always been popular, but never more so than today. There is a long, painful history of bad tree plantation projects mainly in the Global South, but also in the North, where tree planting projects have caused deforestation and social misery, as well as increased climate change. This FAQ explains some of these issues. 
 

Can tree planting solve climate change?  
 

No, tree planting cannot solve climate change. 
 
Trees absorb carbon dioxide (CO2) during photosynthesis, in which they use sunlight to convert that CO2 into the sugars and energy they need to grow. The carbon is stored in biomass – the trunk, roots and leaves – as well as in the soil. Planting trees could therefore help mitigate climate breakdown, since they absorb CO2 as they grow, and the carbon remains stored until the wood decomposes or is burnt.  
 
Tree planting will not, however, help the climate if trees are then cut down and burnt for energy; trees are planted in a way that doesn’t consider local biodiversity needs; trees are planted instead of reducing CO2 emissions (offsetting); tree planting diverts attention from the need to protect existing, mature forests.

Biodiverse tree planting can contribute to addressing the climate emergency, but only if we also reduce emissions and protect and restore existing forests. 
 

Is planting trees and forest restoration the same? 
 

Tree planting and forest restoration do not mean the same thing, though tree planting can be an element of forest restoration, if carried out appropriately. 
 
Tree planting simply refers to the act of planting trees in the ground, usually young trees (or saplings). 
 
Restoration, on the other hand, is returning a forest ecosystem to a previous, healthy state. In a biodiverse natural forest, there are a range of trees of different ages.  
 
The forest keeps re-generating naturally and supports a complex web of flora and fauna. If a forest has been degraded - for example through clearcutting - it may be possible to bring it back to a healthy state. Planting new trees can be part of this, as long as native trees are prioritised, and there is a range of species to ensure biodiversity is maintained. Forests can be restored in different ways including moving from clearcutting and planting monocultures to community forestry, close-to-nature forestry, or ‘setting aside’ land, with community support, to allow the forest to regenerate on its own without any interference.  

Eucalyptus plantation (on the right) versus a diverse forest (on the left)

Are young or old trees more important for absorbing CO2
 

Variations exist in the rate and levels at which trees absorb CO2, depending on the local conditions and exact species involved.  
 
Contrary to some industry claims, trees can continue to absorb carbon well past 600 years of age! Older forests not only continue to remove CO2, they also store huge amounts of carbon in their trunks and roots as well as in the undisturbed soil beneath the forest. The largest 1 per cent of trees contain half of all the carbon, so we need to drop the idea of prioritising young trees over old. 
 
Protecting existing forests are our best hope of tackling climate and biodiversity breakdown.  
 
Any young trees we plant now will be important for the future, but it will take them a long time to catch up with older forests’ ability to store carbon. We therefore need to prioritise protecting and restoring the forests we already have. 
 

What’s the difference between reforestation and afforestation? 
 

Reforestation refers to the planting of trees on deforested lands. 
Afforestation refers to planting trees on land which, historically, has not contained forests. 
 

What tree planting programmes do more harm than good? 
 

The following kinds of tree planting programmes can cause serious damage: 

  • where trees are not suited to the local climate and conditions 

  • where existing biodiverse ecosystems are destroyed or disrupted (for example native grasslands or wetlands which are already acting as important habitat)  

  • where only one kind of tree is planted rather than a mix of species which would be more climate- and pest-resilient 

  • where the trees which are planted are logged over and again without allowing the forest to mature 

  • where soil and water pollution are increased 

  • where local communities are not involved or properly consulted (for example when only those in positions of power have a say), resulting in livelihoods loss, disconnect from nature or land-grabs 

  • where there is a poor project governance, which often results in dead plantations. Plantations and nurseys often have very low success rates and local community governance and knowledge about ecosystems is incredibly important for the health of ecosystems and of people living in them.  

Catégories: FAQs, Restauration

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