Biogeography of Fall Color

Essentially a phenomenon of the northern hemisphere with minor exceptions in some of the Nothofagus forests etc. in the southern Andes (and possibly S. New Zealand?, South Africa?, Tasmania?)

Within the northern hemisphere there are two large zones of fall color:

1. Eastern U.S. and adjacent Canada, mostly east of the Rocky Mountains and encompassing all deciduous forests/woodlands from north to south.  At its best and most diverse in the eastern third of the continent.
2. Deciduous forest/woodland belt of north Asia (Himalayas and north) and adjacent north Europe, at least northeast Europe. Possibly best and most diverse, as in North America, in the easternmost parts of Asia, e.g. Hokkaido and adjacent northeastern China etc.

Areas that seemingly should (or could) have fall color but don’t:

1. Deciduous species of western North America (other than northern parts), i.e. areas of Mediterranean climate, especially California, where only a few deciduous species color up.
2. Corresponding climate region(s) of the greater Mediterranean region of Europe and West Asia (the transition zones being to the north and east, just as in North America, and for the same reasons.