CONICET | Buscador de Institutos y Recursos Humanos

The ruderal strategy is widely shared among non-native plants, providing ageneral explanation for the commonly observed positive effects ofdisturbance on invasions. How native ruderals respond to disturbance andhow their abundance compares to that of non-native ruderals remains,however, poorly understood. Similarly, little is known about the role thatdisturbance type plays in the coexistence between native and non-nativeruderals. We proposed that natural disturbance favors native over non-nativeruderals, whereas novel anthropogenic disturbance favors non-natives overnatives. To assess our general hypothesis, we conducted extensive fieldsamplings in which we measured relative abundance, richness, and diversityof native and non-native ruderals in sites with natural and anthropogenicdisturbance in central Argentina, a system where the ruderal strategy iscommon to a large number of native and non-native species. We found thatnatives dominated ruderal communities growing in recently burnedgrasslands, whereas non-natives dominated in roadsides. Additionally, therichness and diversity of native ruderal species were much greater than thoseof non-natives in sites with fire and in sites with grazing, but species richnessand diversity did not differ between groups in roadsides. Because vegetationevolved with fire in our system and, in contrast, the construction andmaintenance of roads is recent in it, these results support our hypothesis.Our work indicates that the ruderal strategy does not seem to suffice toexplain why disturbance facilitates invasions. According to our data, speciesorigin interacts with disturbance type to determine dominance in communitieswith coexisting native and non-native ruderals.