Trees are the foundation of our entire ecosystem. Trees also provide a wide range of ecological services, such as water filtration, erosion prevention, flood protection, carbon sequestration, and temperature regulation. Not to mention the economic wealth that wood and renewable resources provide.
Agriculture, logging, urbanization, disease, and invasive species threaten a third of all tree species. And it’s not just exotic trees that are affected: half of the magnolia species are threatened with extinction.
A third of the world’s tree species are threatened with extinction, according to the State of the World’s Trees 2021 report. Coordinated by Botanical Gardens Conservation International (BGCI) and experts from the International Union for Conservation of Nature (IUCN), the report covers 58,497 tree species on four continents.
Some 17,510 tree species are classified as threatened with extinction, meaning that their numbers are declining globally or their areas are shrinking. “That’s ten times the number of all threatened mammal, bird, amphibian, and reptile species combined,” warns Paul Smith, BGCI Secretary-General. 440 species are “critically endangered”: less than 50 species still live in the wild, and 142 species have even disappeared altogether. For example, only 10 specimens remain of Diospyros egrettarum, a tree endemic to Mauritius that once dominated the island’s dry coastal forests.
Latin America, which has the world’s largest tree biodiversity with 23 631 species, is particularly threatened: 30% of tree species are classified as endangered. In Indonesia and Malaysia, among the five countries with the highest tree biodiversity in the world, 25% of species are threatened.
Agriculture is responsible for 29% of the extinction risk
Over 300 years, 40% of the 29 countries surveyed have lost more than 90% of their forest cover. This massive deforestation is due to conversion to agricultural land or plantations (coffee, tea, palm oil, soy, rubber, etc.). According to the World Resources Institute, seven major crops alone are responsible for half of the deforestation. Rapid urbanization also tends to accelerate the fragmentation of vegetation, which is thus cut off from its ecosystem. But new factors are increasing pressure on the ecosystem, such as insect pests, invasive species, and climate change. Climate change poses a direct threat to more than a thousand species by altering their habitats and increasing the risk of storms, floods, fires, and disease.
The experts call for a series of measures to protect what can still be protected. The priority, of course, is to preserve existing forests by increasing the number of protected areas. Reforestation, on the other hand, must be done with caution, as it can exacerbate the problem by increasing monoculture or introducing species that crowd out native trees. For critically endangered species, botanical gardens should ensure the survival of the species through seed banks or arboretums.