Online herbaria databases allow testing the minimum residence time among invasive and non-invasive alien species

Abstract

In invasion ecology, the Residence Time (RT) hypothesis suggests that the longer a species has been introduced to a region, the likelier it is to become invasive. However, obtaining information about RT is challenging for many regions worldwide. Consequently, the time since the species was first recorded in the studied area (Minimum Residence Time, MRT) is commonly used. Nevertheless, the study of MRTs in invasive species is uneven across regions. In this study, we integrated online herbaria sources with literature records of both invasive and non-invasive alien species, along with native woody species, to assess whether invasive alien species in central Argentina exhibit longer MRT than non-invasives at two geographic scales. If RT proves to be a significant factor influencing the invasive potential of a species, one would expect invasive species to have extended RT in herbarium records compared to non-invasive ones, although shorter than those of natives that initially drew the attention of early botanists. We observed a higher MRT for native species compared to alien species, suggesting that the online herbaria data used are sensitive to the dynamics of plant communities over time. The patterns were consistent at both scales. Among alien species, invasives exhibited consistently higher average MRT compared to non-invasives at both scales, providing further evidence of the role of time in invasion dynamics. This study’s methodology is applicable to regions lacking information on the introduction history of alien species but having online herbaria, allowing the testing of the RT hypothesis in different world regions.