Novel ecosystems: a review of the concept in non-urban and urban contexts

Context Anthropogenic changes (e.g., climate change, land-use change, species introductions, etc.) are reshaping ecosystems processes and patterns and causing an intense reorganization of the Earth's biotic systems. As a result, unprecedented combinations of species are emerging, forming "novel ecosystems". Objectives The goals of this work are: (1) to examine the history and relevance of the novel ecosystems concept in non-urban and urban contexts, and (2) to evaluate what has been the focus of the research about the novel ecosystems concept in non-urban and urban contexts. Methods Through an extensive systematic review, we collected 548 records published between 1997 and 2018. After applying inclusion/exclusion criteria the final database comprised 255 relevant records that were further examined and classified according to the scope of this review. Results Our results demonstrated that research referring to the novel ecosystems concept has been mainly focused on non-urban areas. Still, there is a growing interest in exploring this concept in the urban domain. The definition and criteria used to describe novel ecosystems have been transforming over the years. Research has been mainly targeted on multiple taxonomic groups and plants, on terrestrial ecosystems, and conducted in North America. Overall, restoration ecology, conservation, biodiversity, ecosystem services, and climate change have been the most discussed topics in the novel ecosystems' literature. Conclusions Our review confirms that the application of the novel ecosystems concept to urban areas is pertinent and auspicious. Future research should seek to understand the limits and differences of novel ecosystems in non-urban and urban contexts.