Figure 3.

Invasion timing affected invasion outcome and compositional effect: (A) mosaic plot representing the relative frequencies of invasion outcomes across the three invasion timing treatments for invasions by P. poae. Invasion outcome was defined as a “success” (bottom box) if the invader persisted over time or a “failure” (top box) if the invader was ultimately excluded. Chi-square test of independence demonstrates a significant association between invasion outcome and invasion timing (P value <6e⁻⁹), with the Pearson residuals indicating invasion success was significantly over-represented in the early-invasion treatment whereas invasion failure was significantly over-represented in the initial-invasion treatment (significantly over- or under-represented outcomes are highlighted). The late invasion results did not significantly deviate from the null expectations. Pearson residuals >2 or <−2 indicate a count value >2 SD from the expectation. (B) Bray–Curtis dissimilarity–based principal coordinate ordinations of communities from each invasion treatment alongside the uninvaded reference communities for comparison. Communities are identified by color; invasion status of the community (uninvaded/invaded) is represented by point shape.