Predicted and Observed Species Abundance
When present, A. elatius increased community biomass (Fig. 5; Supplementary Table 1). A. elatius represented more biomass (90 ± 10%) in the current than the pre-existing (74 ± 16%) experiments (Fig. 5). The second and third most abundant species both attained similar relative biomass in both experiments. D. glomerata represented 61 ± 6% in the current experiment and 58 ± 7% in the pre-existing experiment and this was greater than other species. Similarly, P. pratense represented 44 ± 7% in the current experiment and 40 ± 6% in the pre-existing experiment and that was more than other species (Fig. 5). Null and PSF models predicted A. elatius to be the dominant species (Supplementary Table 4, Fig. 5), contributing 62 % (± 17 %; Null) and 64 % (± 17 %; PSF), respectively, to community biomass. Because D. glomerata performed poorly in Phase 2, models underestimated its relative biomass with 23 % (± 18 %; Null) and 19 % (± 17 %; PSF) compared to observed communities. Thus, D. glomerata was replaced by P. pratense in simulated communities, contributing 56 % (± 21 %; Null) and 55 % (± 22 %; PSF) respectively, to community biomass compared to observations (current: 44 % ± 7 %; pre-existing: 40 % ± 6 %; Fig. 5).