Compared to Western Europe (excluding Southern Europe), North America provides many more arbor species (more than 800 species and about 70 oaks, compared to 51 and three, respectively, in Western Europe)[24] which adds many more different colors to the spectacle. The main reason is the different effect of the Ice ages – while in North America, species were protected in more southern regions along north–south ranging mountains, this was not the case in much of Europe.[25]