This atlas's own cited Wikipedia article and the WWF classification both describe the Pacific temperate rainforest as the world's largest temperate rainforest, but the region is mapped as several separate ecoregions (Northern Pacific coastal forests, British Columbia mainland coastal forests, Central Pacific coastal forests, Klamath-Siskiyou forests and others), each carrying its own area figure in reference sources. No live source found states one combined total for the whole region, and summing the separate ecoregion figures ourselves would be this atlas's own calculation rather than an attested figure taken from a source.
What would resolve this A single authoritative source (WWF or a peer-reviewed biogeography reference) that states one combined total area for the Pacific temperate rainforest as a single region, or that explicitly names which ecoregions such a total should sum.
OpenPhysical geography / biogeographyPacific Temperate Rainforests (Wikipedia)