Figure 3

Effects of species richness on root phosphatase (PME) activity, P and N uptake and biomass production of native and alien Cerrado plants in a mesocosm experiment. (a) Root phosphatase (PME) activity, (b) and (c) total P and N uptake from the soil (mg P in 49 days) and (d) plant biomass (shoot + root) at harvest (t = 7 weeks) of two alien grasses (Melinis minutiflora—orange circles) and Urochloa decumbens—orange triangles), two native Cerrado grasses (Saccharum asperum—blue circles and Setaria poiretiana—blue triangles) and a native leguminous forb (Stylosanthes guianensis—grey losanges) growing in monocultures or in mixtures of two or three species. P fertilization did not have a significant effect on these variables (Suppl. Table 2), therefore the two P treatments were pooled in the regressions. Orange, blue and grey regression lines show significant regressions per species. The dashed black line (ALL) shows the overall effect of the number of species on root PME activity, P and N uptake performed with species identity as random factor (nlme). The design of the experiment is shown in Suppl. Figure 1. Additional statistics are in Suppl. Table 2. To improve visibility of the results in the graphs we subtracted 0.1 or 0.2 from ‘species per mesocosm’ for the alien grasses and added 0.1 and 0.2 for the native grasses.