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]).