There is a wide consent that forests are the most efficient tool to fight the climate crisis. However, the question how we should this forest is highly debated. A lot of foresters argue that a managed forest stores more CO2 than wild forests, because the growth rates of the trees are higher. Recent research shows that this assumption is not true.
Wild forests release CO2 slower
A study from the UK shows that non-native coniferous plantations store CO2 quicker, but this CO2 is soon released into the atmosphere again. While these plantations grow quicker than wild forests, the CO2 is stored in the wood for a much shorter period. Since over half of all timber is used for less than 15 years, the CO2 is often released after a few years. On the other hand, natural forests store CO2 for up to hundreds of years in old-growth trees. The study also warns of the impact for biodiversity of non-native plantations. The fast growing tree species only grow well on highly productive land, which agriculture mostly already takes up. So, they are planted on less productive land, where they replace native biodiversity and give less yield.
Bioenergy cannot compensate deforestation
A study from Finland also warns that increased logging will not be compensated by the use of bioenergy and wood products. This shows that more intense logging to replace fossil fuels would have the opposite effect than desired. It is better for the CO2 balance to leave wild forests as carbon sinks than to use wood as bioenergy.
We understand the economic importance of plantations for many countries. However, natural forests are the only option that can realistically help mitigate climate change.
Biodiversity = Productivity
Researchers from China found that “directed species loss” reduces the productivity of a wild forest. Directed species loss can for example mean that a group of tree species is removed (or passively suppressed) because there attributes are not desired for forestry. If a whole group of species with similar traits is missing from an ecosystem, the system becomes unbalanced leading to less growth is most of the species and thus less carbon sequestration of the whole system. A team from Wageningen University, Netherlands, found similar for grasslands. Biodiverse grasslands are more productive.
Proforestation over Reforestation
A scientific report from 2019 recommends that natural regeneration we should prefer over active planting wherever possible. It is not only much cheaper, it also creates forests that are naturally adapted to local conditions. Recent successes with natural regeneration in Brazil show that is can be upscaled to large areas. With proper planning and management, plantations are only necessary where soils are completely degraded. Another report from the USA came to the same conclusion. While they use the term proforestation – distinguishing it from active afforestation and reforestation – they mean the same thing. They emphasize that to calculate carbon sequestration, we cannot only look at the trees. In a natural forest, soil, wetlands and deadwood also store a lot CO2.
Disturbed forests become carbon emitters
A study about the net carbon emissions of forests around the world shows that highly disturbed forests can turn from carbon sinks to CO2 emitters. Forests in Africa on areas, where substantial land use change has happened recently, have emitted CO2 instead of storing it. The conclude that the reason might be degradation of the soil, which disturbs the natural balance of the ecosystem.
Wild forests are more resilient
A study from Germany shows that the benefits of wild forests might even increase within the next decades. While beech trees in managed forests grow faster under normal conditions, beech trees in umanaged forests were more resistent to droughts. Germany itself has seen unprecedented forest fires and forest dieback in 2018 and 2019 due to a wave of dry and hot periods. And the climate crisis will the increase the number of droughts and heat waves around the world. The study shows that wild forests might be more resistant to these challenges.
The LIFE project GRAZELIFE published preliminary results that advocate natural forests and emphasize the benefits of a structural diverse forest. Wild forests with native wildlife are less vulnerable to fire, have more diverse ways to store carbon, increase biodiversity and reduces soil degradation.
So, what to do?
All these studies show that the answer to the climate crisis cannot be to transform wild forests to wood factories. Wild forests store carbon, protect biodiversity and provide a variety of ecosystem services.
However, using wood as a high-quality construction material must be part of a sustainable transformation. At the moment much wood is used for consumable goods or cheap furniture that gets replaced every few years. Not only nature conservationist plead for a change, foresters have demanded for a long time that the value of this versatile material must be utilized better. Working together, we can protect wild forests AND make wood part of a sustainable transformation.