The distribution and occurrence of plant species, including trees, in the nature show that living and splendor of them is constrained by climatic factors. They have their minimum, optimum and maximum for the temperatures they can survive in. The tree species, at least mostly are divided into different varieties in different areas of the world so that the species are most suitable for the climatic conditions of their site.
The article presents the main climatic zones with their tree species according L. Ilvessalo and they suitability to Finland. More accurate areas of suitable species are also listed.
The referred results show that alongside the climatic conditions, the conditions of soil and relief must be taken into account when using exotic tree species for forestry purposes.