A five-year study of 60 thousand tree species growing on the globe showed that 30% of them are currently under threat of extinction.
"That means there are twice the number of threatened tree species globally than threatened mammals, birds, amphibians and reptiles combined," said the Botanic Gardens Conservation International (BGCI), which published the State of the World's Trees report.
More than 440 tree species are generally on the verge of extinction - less than 50 of them remain outside parks and nurseries, and at least 142 species are registered as already extinct in the wild.
The country with the most endangered tree species is Brazil. In the Latin American country, there are 8847 of them - an absolute record in the world, but about a fifth (1788) is endangered. Indonesia and Malaysia are also among the five most biodiverse countries in the world with 5,716 and 5,422 tree species respectively, and nearly 25% of them are threatened.
The main problem is agriculture, land clearing for which affects 29% of tree species. It is followed by logging (27%), livestock (14%), urbanization and fires (both 13%).