Herbivore pressure on native and non-native plant species
In the field survey of 28 sites, 396 individuals of 27 non-native plant
species and 678 individuals of 59 native plant species were evaluated.
There were large differences among non-native plant species (χ² = 3744,
P < 0.001, Figure 1A) and among native species (χ² = 3025, P
< 0.001, Figure 1B) in herbivore damage, with non-native plant
species damaged 46.2% less than natives (χ² = 22.63, P<0.001,
Figure 1C).
In the common garden experiment, herbivore damage varied by over an
order of magnitude among non-native species (χ² = 198.43, P <
0.001, Figure 1D) and among native species (χ² = 71.22, P <
0.001, Figure 1E). Herbivore damage on non-native species was 41.5%
less than on natives (χ² = 6.53, P = 0.011, Figure 1F).
Non-native plant species with higher herbivore biomass on them received
more leaf damage in the field survey (r = 0.97, P < 0.001,
Figure S3A) and in the common garden (r = 0.38, P < 0.001,
Figure S3B). Furthermore, there was a strong positive linear
relationship between herbivore damage on particular species in the field
survey and those species in the common garden experiment (r = 0.88, P
< 0.001, Figure S4).