Tree planting initiatives are among the most popular ways that companies contribute to mitigating climate change – with some using reforestation to negate their carbon footprint; however, some trees planted in the tropics can do more harm than good.
Trees can offer many benefits to the environment. They can store carbon, filter air, create habitats, and provide various benefits for people and animals. Planting the right trees in the right habitat and consultation with locals can support goals like addressing climate change.
However, new research from UMBC (University of Maryland, Baltimore County) has found that 92 per cent of plantations were in biodiversity hotspots, threatening a range of animal and plant species.
Furthermore, 14 per cent of plantations were in arid biomes (dry regions), where trees are unlikely to thrive and likely to damage existing ecosystems, with 9 per cent intruding accessible protected areas like national parks.
The most common tree plantation species were eucalyptus, rubber, and oil palm.
“Ecologists have sounded the alarm on this for over a decade. But no one’s had a hard number about how much this is happening,” explains Matthew Fagan, lead researcher and assistant professor of geography and environmental systems at UMBC.
According to their study, China has committed to a massive tree-planting effort at the edge of the Gobi desert, and many countries have committed to planting trees during the transition between the Sahel grassland and the Sahara.
The goal is to prevent desert expansion, but the plantlings disturbed the soil, releasing carbon, and their choice of trees was “water hogs”. The new trees kill off the existing grassland, and then they eventually die out of drought.
“In these situations, tree planting is lose-lose,” he said.
Similarly, in Brazil, soy farmers moved out of the Amazon and into the Cerrado, one of the world’s biggest savannas. Pine and eucalyptus tree farms followed.
“The Cerrado supports a wealth of biodiversity, and the carbon it stores underground rivals rainforest carbon sequestration,” he said.
“Tree crops in the Cerrado may count toward Brazil’s reforestation commitment but could be a step backward in mitigating climate change and biodiversity loss.”
Fagan added that people tend to idolise tree planting as the ultimate environmental act. Still, there’s value in grasslands and savannas that people don’t initially understand. Not all trees are beneficial for the ecosystem involved.
“The right tree in the right place is the right answer,” he concluded.