Abstract
Classical and cryptic glacial refugia plant species' potential range (fundamental niche) is delineated by a climate space that they often occupy only partially (realized niche). Generally, temperate plant species tend to occupy a wider geographical range when climate is warm and wet, and retract when climate is cold and dry. During the last glacial period, cold-tolerant herbs dominated the mid-to high-latitude landscape in both hemispheres and the range of most temperate tree species was reduced to discrete populations until the climate became warmer and wetter during the Holocene, which allowed them to expand.