One boreal forest, but many tropical rainforests
Biogeographers divide up the terrestrial ecosystems of the
world in two fundamentally different ways: (i) into biomes,
defined by the dominance of particular plant functional
types; or (ii) into biogeographical regions, based on the
distribution of plant and animal taxa. In the northern
temperate zone, where most ecologists live and work,
these two classifications are confounded, because the
major temperate biomes occur within a single biogeographical
region, the Holarctic (divided for some purposes
into two, the Nearctic and Palearctic).