3.1 Biomass Production
Species biomass was best explained by the full model (𝛿AIC = 7.31) including site, species, an interaction between site and species, an interaction between climate and soil, and a three-way interaction between climate, species and soil (F35, 133 = 11.22, p < 0.001). Prevalence of interactions across all explanatory factors reveal highly contingent biomass dynamics. Lower species-specific biomass was observed at Bayreuth (350 m) than at Fendt (550 m) and Stubai (1850 m) (TukeyHSD, p < 0.001, p = 0.016 respectively). All species produced more biomass at Fendt (550 m) compared to Graswang (850 m), Esterberg (1300 m), Furka (2440 m) (TukeyHSD, all p < 0.001) and Stubai (1850 m) (TukeyHSD, p = 0.021). Lower species-specific biomass occurred at Furka (2440 m) than at Stubai (1850 m) (TukeyHSD, p = 0.006). Species differed in biomass production across all climates except Esterberg (1300 m), with no species consistently producing the most biomass across all sites (Fig. 3 ).
Individual biomass was best explained by the model including climate, soil, an interaction between climate and species, as well as an interaction between soil and species (F20, 148 = 11.22, p < 0.001). This contrasts with the best-performing model explaining community biomass, which was the full model. Interestingly, community biomass hierarchies were generally conserved when measured using individual-level biomass (unlike at the species level). Lower individual biomass was measured at Bayreuth (350 m) than at Fendt (550 m) and Esterberg (1300 m) (TukeyHSD, both p < 0.001), while higher individual biomass was recorded at Fendt (550 m) than Graswang (850 m), Stubai (1850 m), and Furka (2440 m) (TukeyHSD, p < 0.001, p = 0.006, p < 0.001 respectively). Higher individual biomass was measured at Esterberg (1300 m) than Graswang (850 m) and Furka (2440 m) (TukeyHSD, both p < 0.001), while Stubai (1850 m) had higher individual biomass than Furka (2440 m) (TukeyHSD, p = 0.001). Individual biomass production differed by species. Different dominance hierarchies were observed when the number of individuals was accounted for than when biomass was pooled at the species level in all sites but Esterberg (1300 m). While species-level biomass was not affected by soil type (F1, 167 = 0.34, p = 0.562), individual biomass was, with reference soil having a higher individual biomass across all climates than local soil (F1, 167 = 14.85, p < 0.001). Interestingly, the higher individual biomass corresponded to the reference soil also having a higher root biomass and lower survival when compared to the local soil (F1, 58 = 7.698, p = 0.007; F1, 58 = 15.68, p < 0.001 respectively). This revealed an interesting survival dependent positive relationship between the individual biomass and the species biomass in each community (Fig. 4 ).