Relationship between forest area and occupancy by the exotic plant Alliaria petiolata. (a) Correlation coefficient between forest area and occupancy by A. petiolata at each radius (range: 120–2020 m) among the study forests. (b) Relationship between forest area at 1320 m radius and occupancy by A. petiolatai. Data for the radius with the highest correlation coefficients regarding the effects of forest area are shown. Code numbers next to the circles indicate study site codes, which are provided in Table 1. Correlation coefficients in the shaded grey areas are statistically significant at p = 0.10 level. Line represents a linear regression: occupancy by A. petiolata (AP, proportion of maximum numbers of quadrates out of 234), arcsin= 0.6452 – 0.5800*log(FA), r2 = 0.56, F1,5 = 6.46, p = 0.052.