Non-native plant species benefit from disturbance: a meta-analysis

Disturbances, such as fire and grazing, are often claimed to facilitate plant species richness and plant invasions in particular, although empirical evidence is contradictory. We conducted a meta-analysis to synthesize the literature on how non-native plant species are affected by disturbances. We explored whether the observed impact of disturbance on non-native plant communities is related to its type and frequency, to habitat type, study approach (observational or experimental), and to the temporal and spatial scales of the study. To put the results in a broader context, we also conducted a set of parallel analyses on a data set involving native plant species. The diversity and abundance of non-native plant species were significantly higher at disturbed sites than at undisturbed sites, while the diversity and abundance of native plant species did not differ between the two types of sites. The effect of disturbance on non-native plant species depended on the measure used to evaluate the impact (species diversity or abundance) and on disturbance type, with grazing and anthropogenic disturbances leading to higher diversity and abundance of non-native plant species than other disturbance types examined. The impact of disturbance on non-natives was also associated with study approach, habitat type and temporal scale, but these factors covaried with disturbance type, complicating the interpretation of the results. Overall, our results indicate that disturbance has a positive impact particularly on non-native plant species (at least when they are already present in the community), and that the strength of this impact depends primarily on the disturbance type. Synthesis Empirical evidence of the effect of disturbances on plant species richness is contradictory. Here we use a meta-analysis to synthesize the published literature on how different types of disturbances influence the diversity and abundance of plant species, focusing in particular on non-native plants. Our study supports the hypothesis that disturbances generally facilitate the diversity and abundance of non-native plant species, although the strength of this facilitation depends primarily on the disturbance type.