Plant Biomass
We did not detect an interaction between warming treatment and trophic
level (df = 6, Chisq = 7.98, p = 0.24) on above-ground plant biomass,
although there were main effects of warming treatment (df = 3, Chisq =
16.18, p = 0.001 ; Figure 1) and trophic level treatment (df = 2, Chisq
= 27.88, p < 0.001). In the absence of an herbivore and
predator, plant biomass was significantly larger in constant- (1.03 ±
0.05g, p = 0.048), day- (1.05 ± 0.06g, p = 0.029), and night-warming
treatments (1.09 ± 0.06g, p = 0.007) relative to the ambient treatment
(0.79 ± 0.05g). In the absence of a predator there was not a significant
effect of warming treatment on plant above-ground biomass (df = 3, Chisq
= 5.45, p = 0.14). When all three trophic levels were present, warming
treatment tended to have an effect on above-ground plant biomass (df =
3, Chisq = 6.57, p = 0.087), with an increase in the night-warming
treatment (0.92 ± 0.09g) compared to ambient (0.65 ± 0.04g), constant
(0.73 ± 0.11g), and day-warming treatments (0.66 ± 0.08g).