Resident biodiversity was affected unimodally by disturbance, whereas density linearly
Resident biodiversity (Simpson’s index) showed the same unimodal pattern across disturbance frequencies irrespective of invader type (SM invader: F1,86=10.3, p=0.002, WS: F1,79=7.87, p=0.006) with the least diverse communities at both high and low disturbance (Fig. 3). Resource abundance also altered resident biodiversity (SM invader: F2,86=3.84, p=0.025, WS: F2,79=33.1, p<0.001), with diversity being significantly lower in the low resource treatment than the medium when invaded by SM (p=0.025) and lower than both the medium and high resource treatments when invaded by WS (p=<0.001 for both).
Like biodiversity, resident density showed the same patterns irrespective of invader type (Fig. 4), with an interaction between disturbance frequency and resource abundance significantly affecting density (SM invader: F2,85=49.4, p<0.001, WS: F1,79=47.0, p<0.001; Fig. 4). Resident density increased with disturbance under high resources, but disturbance negatively impacted density at low and medium resources (Fig. 4).