Distance to suburban/wildland border interacts with habitat type for structuring exotic plant communities in a natural area surrounding a metropolitan area in central Chile

Abstract

Background: The explosive growth of urbanisation in Mediterranean ecosystems in Chile has favoured the rapid expansion of exotic plant species, yet factors driving these invasion patterns in adjacent natural areas remain poorly assessed. Aims: To assess how distance to a suburban/wildland border, habitat type, site-scale disturbance and woody plant cover of native species influences the diversity of exotic species in a natural area surrounding the city of Santiago, Chile. Methods: Three watersheds were chosen, and the diversity of exotic species was assessed in 36 100-m-long transects, equally distributed over two distance categories and three habitats. For each transect, we measured woody plant cover of native species and frequency of rabbit faeces as a measure of competitive exclusion and site-scale disturbance, respectively. Results: Species diversity decreased as the distance from the suburban/wildland border increased, and it was found to be higher in north-facing habitats compared to south-facing and alluvial habitats. Neither native woody plant cover nor frequency of rabbit faeces had an effect on species diversity. Conclusions: The current pattern of exotic plant species in this natural area is mainly influenced by the distance to suburban border and habitat type. An adequate management of conditions favouring exotic species in suburban/wildland border may prevent the spread of these into natural areas next to urban settings.