Invasion success (invader proportional change) differed between invader types
Invader success was significantly affected by a 3-way interaction between disturbance frequency, resource abundance and invader morphotype (F2,163=10.2, p<0.001; Fig. 2). We therefore analysed treatment effects on each invading morphotype separately. The fast-growing smooth (SM) invaders were significantly affected by an interaction between disturbance frequency and resource abundance (F2,85=9.7, p<0.001, Fig. 2). Greater disturbance increased invasion success when resources were abundant (slope = 0.12, 95% CI [0.2, 0.050]), but decreased success when they were of low abundance (slope = -0.089, 95% CI [-0.020, -0.16]). Disturbance had no significant effect under medium resource abundance (slope = -0.048, 95% CI [0.021, -0.12]). This meant the highest levels of SM invasion occurred when both disturbance frequency and resource abundance was high.
Wrinkly spreader (WS) success was also affected by an interaction between disturbance frequency and resource abundance (F2,78=3.31, p=0.042; Fig. 2). Here we found disturbance to be negative for WS success when resources were high (slope = -0.24, 95% CI [-0.11, -0.37]), but to have no effect when they were at medium or low abundance (medium: slope = -0.033, 95% CI [0.069, -0.14]; low: slope = -0.076, 95% CI [0.026, -0.18]).