Native or Exotic: A Bibliographical Review of the Debate on Ecological Science Methodologies: Valuable Lessons for Urban Green Space Design

Abstract

Knowledge from ecological sciences is an important reference for landscape design as Urban Green Spaces (UGS) play a critical role in the ecological protection of cities. There is an ongoing debate among ecologists on the value of exotic vegetation to ecosystem resilience and integrity, with authors arguing that in order for ecosystems to survive in future climates, exotic species with similar conditions in their current range must be considered. Others deem biodiversity vital for ecosystem functions and services, stating that most biodiversity losses are man-induced and should be addressed through the enhancement of native communities. Through a literature review, we confronted the arguments used in this debate, with the aim of conducting a comprehensive analysis of the potential of exotic and native vegetation in different aspects of the vegetation’s performance. The outcomes are important for the assessment of vegetation assemblages within UGS projects. Despite the strong arguments regarding their performative and adaptive capacity, we conclude that exotics pose significant ecological risks and have multiple negative impacts on ecosystem processes. Natives not only present high adaptive capacity, but also provide additional benefits for biodiversity, ecosystem integrity, and for people. In a broader framework, the literature demonstrates a preference for the use of native species in most situations.

Evaluation-perception of site attributes and plant species selection in the public urban green space of a compact city

“…Across all cluster groups, people valued the species attribute "provide food and habitats for wildlife" much more important than "native plant species," with a mean score difference ranging from 0.7 to 1. A recent review study by de Carvalho et al (2022) indicated general views that native plant species favor and support native fauna, and exotic plant species negatively affect native fauna and also support exotic fauna. Over the decades, various studies showed that exotic plants could decrease the food availability for insects that feed on plant tissues (Sjöman et al 2016), and native plants were more likely to provide resources for urban animals and increase biodiversity in UGS (Mohamad et al 2013, Berthon et al 2021.…”

Different Jargon, Same Goals: Collaborations between Landscape Architects and Ecologists to Maximize Biodiversity in Urban Lawn Conversions

“…There is an ongoing debate among factions of landscape architects and, to a lesser extent, ecologists, on the role of exotic vegetation within managed landscapes [34]. One side argues that, in the face of climate change, a plant's adaptability and the ecosystem services they provide are more important than their geographic place of origin (for example, [35][36][37] The other side argues that a massive loss of biodiversity is underway due to the effects of climate change, biological invasion, and human disturbance and that the introduction of exotic vegetation (including lawns) further contributes to the losses [38][39][40][41].…”

New Alien Plant Taxa for Italy and Europe: An Update

“…Although not all introduced plants become invasive [ 17 , 18 ], the ability to become invasive should not be underestimated, both for casual and naturalized alien taxa [ 19 ]. Alien taxa are often introduced into urban green spaces, having more advantages than disadvantages compared to native species [ 20 ].…”