Restore old forests instead of planting new ones to offset carbon, say Oxford scientists

A carbon-offsetting project near Carlisle in Cumbria
A carbon-offsetting project near Carlisle in Cumbria - Construction Photography/Avalon/Hulton Archive

Old forests should be restored to their former glory instead of focusing on creating new plantations, Oxford scientists have said.

The current goal of making homogenous forests of the same handful of tree species in orderly rows in order to offset carbon emissions is a flawed approach and offers minimal benefits while damaging biodiversity, they say.

The single-minded focus on carbon emissions has reduced the importance of other roles of forests, the experts warn, and a better approach would be to prioritise conserving and restoring intact ecosystems.

“Current and new policy should not promote ecosystem degradation via tree plantations with a narrow view on carbon capture,” Dr Jesús Aguirre-Gutiérrez writes in his article, published in the journal Trends in Ecology and Evolution.

The member of the University of Oxford’s Environmental Change Institute says the approach of afforestation, which involves creating plantations on previously unwooded areas, is not enough to replace the rich diversity of natural forests that has been lost.

Tropical ecosystems are highly biodiverse, and they provide multiple ecosystem services, such as maintaining water quality, soil health and pollination.

In comparison, carbon-capture plantations are usually monocultures and are dominated by just five tree species – teak, mahogany, cedar, silk oak, and black wattle – grown for timber, pulp or agroforestry.

Lower level of biodiversity

The scientists say that modern plantations support a lower level of biodiversity of up to 40 per cent.

Dr Aguirre-Gutiérrez added: “The current trend of carbon-focused tree planting is taking us along the path of large-scale biotic and functional homogenisation for little carbon gain.

“An area equivalent to the total summed area of the US, UK, China and Russia would have to be forested to sequester one year of emissions.

“There are considerable financial incentives for private companies to offset their carbon emissions by investing in carbon capture and that the boom in carbon-capture plantations is being driven by money, not ecology.

“Over-emphasising the benefits of tree planting for carbon capture can disincentive the protection of intact ecosystems and can lead to negative trade-offs between carbon, biodiversity and ecosystem function.

“An overarching view on maintaining original ecosystem functioning and maximising as many ecosystem services as possible should be prioritised above the ongoing economic focus on carbon capture projects.”

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