Urban ecological novelty assessment: Implications for urban green infrastructure planning and management

Urban areas are continuously subjected to anthropogenic transformations that result in the emergence of novel urban ecosystems. To prepare for and respond to contemporary negative environmental impacts (e.g., climate change, land-use change, biological invasions), it is increasingly urgent to plan and adapt cities' green infrastructure. Accordingly, the inclusion of the novel ecosystems concept in urban planning and management is pertinent and necessary. Nevertheless, identification or measurement of ecological novelty has been challenging and can be problematic without the appropriate methods. The objectives of this study are to 1) develop and test a methodology to assess novelty in urban ecosystems grounded on the combination of both human and biotic dimensions of the novel ecosystems concept, and 2) discuss the implications that urban ecological novelty assessment can have for future urban green infrastructure planning and management. In contrast to other proposed methods, this assessment considers the human dimension of the concept as equally important as the biotic dimension, once the human presence is pervasive and a fundamental component of urban landscapes. The proposed working methodology was tested in Porto, Portugal, in study sites with contrasting human-induced transformation pathways and plant species assemblages, thus theoretically representing different degrees of urban ecological novelty. The methodology developed in this work is straightforward and can be adjusted and replicated to other cities according to available data and tools. Above all, the assessment of urban ecological novelty can inform future urban planning and management and assist in investigating novel urban ecosystems.