A b s t r A c tNortheast Asia includes the mainly temperate-deciduous and boreal forest areas of the Russian Far East, Manchuria, northern China, Korea, and northern Japan. In terms of global zonation, the region includes parts of the boreal, cool-temperate and typical-temperate zones, plus polar and the respective mountain belts. Zonation in Russia also recognizes sectoral subdivisions that represent the gradient from the ultra-continental interior to the maritime Pacific areas. Northeast Asia is compared herein with other regions of the Northern Hemisphere, within this zonal framework, in terms of bioclimatic conditions and zonation, vegetation types, main tree taxa, limiting mechanisms and ranges of taxa, and taxon richness. Northeast Asia has greater climatic extremes and climatic diversity, and species richness is generally seen as higher than in comparable areas of eastern North America and Europe. To some extent this results from the separation of Japan, Kamchatka, Sakhalin, and Korea from the East Asian mainland by the large marginal seas. Cool-temperate mixed forests seem strikingly similar in Northeast Asia and northeastern North America, although the extent of the former is truncated in some areas by the sudden appearance of permafrost. Some vegetation types of Northeast Asia are seen as more unique. Several research needs are identified by this cross-continental comparison, especially the need for more complete information on taxon ranges (including full range maps), a common zonation vocabulary, and better climate data. Consideration of the region as a whole also focuses attention on questions of just what really are different species and what factors limit them.