Fig. 2.

Percentages of different groups of life on Earth that live in soil. Species that live in, on, or complete part of their life cycle in soil were classified as “species in soil”. The global percent of species in soil, including or excluding phage, summarized across all groups is also shown. Bars represent the mean and error bars are plus or minus one SE (where >1 prediction was available) of the lower, central, and upper estimates (e.g., for bacteria, we estimate 22.2, 43, and 88.8% for the lower, central, and upper estimates, respectively, for an average of 51 ± 20%). Note that some groups do not have a lower, central, and upper species richness estimate (e.g., Mammalia; see Table 1), and there are no error bars for these groups. See Table 1 for an estimate of the total number of taxa on Earth and those living in soil for each taxonomic group as well as our confidence in each prediction.