Table 1. Scaling parameters between body mass and metabolic rate among different groups of fungi and other microorganisms.

Taxon group	Log(a) (±s.e.)	Scaling factor (b) (±s.e.)	r2	P-value	Sample size (number of species)	Data source
Scaling to biomass accumulation
Ectomycorrhizal fungi (20º)	−2.7 (0.21)	0.58 (0.15)	0.39	0.001	24	(Wilkinson et al., 2012a,2012b)
Marine fungi (20º)	−1.6 (0.35)	0.53 (0.09)	0.92	0.009	5	(Fuentes et al., 2015)
Endogenous protists (20 °C)	−3.12 (0.30)	0.93 (0.04)	0.92	2.2 × 10−16	52	(DeLong et al., 2010)
Active protists (20 °C)	−2.53 (0.59)	0.90 (0.08)	0.69	3.35 × 10−14	51	(DeLong et al., 2010)
Endogenous prokaryotes (20 °C)	0.76 (1.29)	1.27 (0.10)	0.55	2.2 × 10−16	121	(DeLong et al., 2010)
Active prokaryotes (20 °C)	7.02 (1.83)	1.7 (0.15)	0.75	2.91 × 10−14	44	(DeLong et al., 2010)
Scaling to radial extension rate
Saprotrophic fungi (12º)	−2.01 (0.04)	0.62 (0.15)	0.67	0.087	5	(Crowther and Bradford, 2013)
Saprotrophic fungi (20º)	−1.91348 (0.04)	0.53 (0.07)	0.92	8.96 × 10−3	5	(Crowther and Bradford, 2013)
Saprotrophic fungi (28º)	−1.81469 (0.09)	0.85 (0.21)	0.14	0.52	5	(Crowther and Bradford, 2013)

The proportionality constant ‘a’ and the scaling factor ‘b’ were calculated as the slope of the log–log relationship between body mass and metabolic rate for ectomycorrhizal and marine fungi, bacteria and, protozoa; or corresponding to the log–log relationship between metabolic rate and colony extension rate for saprotrophic fungi (using ordinary least square regression). Standard errors for each parameter are given in parenthesis. Data on ectomycorrhizal fungi were standardized to 20°C following DeLong et al. (2010) (The sample size of the ectomycorrhizal data also include different genotypes of the same species, see Supplementary Information for further details on data, transformations and calculation of parameters).