We now know that 30% of tree species are threatened with extinction, and at least 142 tree species are recorded as extinct. The main threats to tree species are forest clearance and other forms of habitat loss, direct exploitation for timber and other products and the spread of invasive pests and diseases. Climate change is also having a clearly measurable impact.

Tree diversity is unevenly distributed across the globe. The largest number of tree species is in Central and South America, followed by the other tropical regions of Southeast Asia and Africa. The highest proportion of threatened species is found in Tropical Africa, which includes Madagascar which is one of the countries with the highest level of threatened trees.