Effects of past landscape and habitat changes in plant invasion provide evidence of an invasion credit

Habitats differ in the invasion degree due to habitat properties and current spatial context. Historical context effects (i.e. land use change legacy) have been little studied and can be modulated by the invasion credit (the delayed increase in habitat invasion after changes in the land use). In this study we considered historical context to know if habitat changes affect the diverse components of plant invasion (introduction, establishment and spread) and to find evidence of invasion credit. The study is performed in the Barcelona province and consists in 531 sampling points distributed along 9 different habitats where we sampled the abundance (cover percentage) of each recorded alien plant species. Habitat and current and historical (past landscape and changes) spatial context variables were used to create the best model explaining introduction and establishment (presence and richness) and spread (mean abundance) of alien species in sampling points. The results show that alien species presence and richness are mostly influenced by habitat and topography but also by the number of changes, which suggests an effect of the land use legacy. The relationship between the historical landscape and alien species abundance provides evidence of an invasion credit. In conclusion, we have found evidence of an invasion credit in the spread stage while there is an effect of the historical legacy in the introduction and establishment. However, habitat invasion is a complex process affected by several factors such as species traits, the introduction event and residence time that should be considered in further studies.