Native versus exotic Plant species in the vacant land of four Portuguese cities: urban ecology and landscape architecture

Abstract

The contemporary city has been growing discontinuously, leaving abandoned structures and vacant land in its wake. The current situation has been caused by economic uncertainty, real estate speculation, and continuous suburban development. The existence and relevance of this issue is well-established in the literature, and recent publications have shifted focus toward how to “reuse” vacant land and abandoned structures. In the scope of the research NoVOID Project – “Ruins and vacant lands in the Portuguese cities: exploring hidden life in urban derelicts and alternative planning proposals for the perforated city”, funded by the FCT (PTDC/ATP-EUR/1180/2014) were identified and classified the main vacant and derelict urban spaces in four Portuguese cities: Lisbon, Barreiro, Guimarães, and Vizela. The research starts from the idea that vegetation is a fundamental structuring element in landscapes. Not only does it dominate most land ecosystems through its biomass, but it also constitutes the habitat for animal populations and is at the heart of the majority of human productive and cultural activities. It is also the element that best integrates a landscape’s biological response to environmental factors (physical, biological and anthropic). A botanical research was performed to a sample of twenty sites located in the four cities under study, to the different types selected (ruins, ruins, and yard and vacant lands), including the following phases: construct a floristic inventory with all the taxa found; establish the ratio of native and exotic species and identify the invasive species; identify the presence of RELAPPE species (in Portuguese: rare, endemic, localized, protected (e.g., species in the Habitats Directive), threatened or endangered). In total, 339 different species of plants were identified, 73% of which are native [32% represent synanthropic ruderals species, 1% (4 species) Iberian endemism, and only 1 specie is protected in Portugal] and 27% exotic (being 14% invasive or potentially invasive). This study furthers the discussion on the ecological, functional, and aesthetic potential that vacant land and ruined spaces have in contemporary cities. Repurposing these spaces through innovative landscape architecture, for either temporary or permanent uses, represents a crucial step toward enriching urban life.