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Ecologists say reforestation must utilise numerous tree species

Biodiversity could be at risk if tree-planting schemes only make use of one type of tree, experts say.

It’s a common saying that variety is the spice of life. If true anywhere, it’s in nature.

While tree-planting schemes are great initiatives for developing new carbon sinks and reforesting diminished green spaces, experts say we risk losing biodiversity if only one or two types of trees are being planted across wide areas.

This is especially the case in regions which naturally host an abundance of species, such as the Amazon and the Congo Basin. Ecologists have warned that the consequences of monoculture tree-planting schemes here are much greater as they threaten the balance of existing flora and fauna.

Things look bleaker when non-native species are introduced to such areas.

Many projects have implemented commercial pine, eucalyptus, and teak plantations in the tropics for carbon offsetting. Unfortunately, these species have dried out native ecosystems, acidified soils, driven out space for native plants, and failed to prevent the spread of wildfires.

Noticing these unintended consequences become a reality in once-biodiverse areas, ecologists at the University of Oxford decided to publish their findings for the public. They state that it’s not too late to stop this situation from worsening.

The motivation behind most tree-planting projects is to commodify areas of forest so they may be later used for carbon credit schemes. Seeing an uptick in these plans, it is clear that ecosystems like the Amazon, Congo Basin, and other major forested regions are being reduced to their carbon value.

The authors of the paper recognise that humans have historically utilised land for whatever brings the most profit and benefit to us. This includes clearing forests to grow food, medicinal plants, and timber – all of which are essential to our survival.

But as we attempt to inch closer to our green targets, the authors of the study say, we are doing the same thing with trying to ‘capture carbon,’ an effort that will be largely ineffective without the right approach and strategy.

‘These schemes are a win for the company planting these trees but not for biodiversity. This is the start of this phenomenon, hence the seriousness of the situation,’ says Jesús Aguirre-Gutiérrez, an ecologist at the University of Oxford who led the research paper.

The environmental benefit we will reap will be entirely dependent on the scale and type of restoration taking place. But it’s also worth noting that allowing natural forests to regenerate could return 40 times as much carbon as new plantations, according to a 2019 study.

As always, the fastest way we can decarbonise the planet is by halting the use of fossil fuels globally. Tree-planting projects, even when using a diverse range of species, should not be viewed as an alternative.