Here is a neat map which shows the range of tree diversity across the entire earth, as compiled by a combination of ground surveys and satellite scans. You can see many areas where there are no trees at all (deserts, American central plains, Arctic) and other areas where the variety of trees is very diverse. The Southeast is an area with a lot of natural tree diversity. You can see the map in a larger format and read more at https://www.morningagclips.com/complete-world-map-of-tree-diversity/.