Classifying the effect of urbanisation on non-indigenous species using the stage-based approach

A case-study on Phragmites australis

Abstract

Urban environments are centres for human activity and environmental change, providing an ecosystem that is frequently disturbed and outside the evolutionary path of local species. The combination of these factors, along with other characteristics of the human dominated environment, create an environment which is ideal for non-indigenous species to out-compete indigenous ones, potentially becoming invasive. The process by which a non-indigenous species is transported to a novel environment and becomes invasive can be analyzed using the stage-based approach to invasion ecology. The four stages identified in this framework are transport, establishment, spread, and impact, with different pressures affecting the non-indigenous species at each stage of the process. In this review, we identify how urbanization has the potential to facilitate the invasion of non- indigenous species with respect to each of these stages. We then apply this framework to Phragmites australis, an invasive reed which is widespread and invasive in many urban environments in North America.

Key words: Phragmites australis, urbanisation, stage-based approach, non-indigenous species, transport, spread, establishment, impact