About a third of tree species across the world are threatened with extinction, according to a report released Wednesday, which warns that climate change could damage entire forest ecosystems.
This “State of the trees in the world” was coordinated by the Botanical gardens conservation international (BGCI), which brings together botanical gardens, and experts from the International Union for the Conservation of Nature (IUCN).
It covers 58,497 species of trees. It shows that 30% (17,500 species) are threatened with extinction, with an additional 7% “possibly threatened”.
Even common trees, such as magnolias, are among the most endangered, oaks, maples and ebony not being spared.
Data is lacking to assess 21% of species and just over 40% are considered not to be endangered.
Logging and deforestation to make way for crops or livestock are by far the biggest threats to trees.
A total of 142 species are considered extirpated and more than 440 are on the verge of being so, with fewer than 50 trees existing in the wild worldwide.
“Many species are on the verge of extinction, some still counting only one living individual”, warns Jean-Christophe Vié, director general of the Franklinia foundation based in Switzerland, in the presentation of the report.
He finds “shocking” the still high levels of deforestation, as trees play a vital role in nature, providing habitat for many animal and plant species, absorbing CO2 and providing ingredients for some medicines.
Brazil, which is home to a large part of the Amazon rainforest, has the largest number of tree species (8,847) including those threatened (1,788), a consequence of intensive agriculture.
But the highest proportion of threatened species is found in tropical regions of Africa, in particular in Madagascar and Mauritius where 59% and 57% respectively of the species are endangered.
In Madagascar, the cultural importance of the Grandidier baobab, which can live around 2,000 years, has not protected it from fires, slash-and-burn agriculture or overexploitation for its bark and fruits.
“Tree species that have evolved over millions of years, adapting to climate change, cannot survive the avalanche of human threats,” warns Jean-Christophe Vié.
“How lacking in foresight do we have to allow the loss of tree species on which societies around the world are ecologically and economically dependent,” he asks.
The report also points to the cascading consequences caused by this destruction. For example, he cites the disappearance of one million hectares of spruce trees in Alaska and about 10 million hectares of lodgepole pines in British Columbia.
Forest ecosystems can collapse when subjected to several threats, such as fires, logging and habitat fragmentation that can “lead to abrupt ecological change,” the report explains.
“Climate change has the potential to become the leading cause of collapse in most, if not all, forest ecosystems,” said Adrian Newton of Bournemouth University in the report.
Global warming thus directly threatens more than a thousand species, by modifying their habitat, by increasing the risks of storms, floods, fires or even diseases.
For Jean-Christophe Vié, the restoration of forests to fight against climate change is “a great opportunity to change this terrible image”. But you have to make sure that the right trees are planted in the right place, he emphasizes.
“If we could only learn to respect trees, many environmental challenges would undoubtedly benefit,” he notes.