9780521861724htl 1..2

There was an interaction between this effect and ‘experiment’ in analysis one:

there was no biomass increase due to species richness in the warming experi-

ment data.

Analysis two showed a significant three-way interaction between average mass,

species richness and environment, indicating that the slope of the relationship

depended on the interaction of species richness and environmental temperature.

In the warming experiment, the large and directional changes in average cell

mass that occurred when warmed communities lost their large top predator

Table 13.2Summary of analysis two of the population consequences of body size
on population density, the response variable. M¼body mass, T¼trophy,
TB¼bacterivores, TO¼omnivores.

ANOVA table

Df Sum sq Mean sq F value Pr(>F)

M 1 625.23 625.23 795.4230 <2e16**
T 2 5.25 2.62 3.3367 0.03775
Residuals 181 142.27 0.79

Coefficients
Estimate Std. error t value Pr(>|t|)
(Intercept) 1.38488 0.27125 5.105 8.3e07
M 0.94759 0.04251 22.291 <2e16
TB 0.26031 0.14711 1.769 0.0785
TO 0.24933 0.24332 1.025 0.3069

Table 13.3Summary of analysis three of the population consequences of body size

on population density, the response variable. M¼body mass.

ANOVA table

Df Sum sq Mean sq F value Pr(>F)

M 1 123.164 123.164 238.63 <2.2e16***

Residuals 173 89.290 0.516

Coefficients

Estimate Std. error t value Pr(>|t|)

(Intercept) 0.15208 0.16945 0.898 0.371

M 0.52241 0.03382 15.448 <2e16 ***

CONSEQUENCES OF BODY SIZE IN MODEL MICROBIAL ECOSYSTEMS 255