Traditional construction systems based on biomass from invasive alien species: the case of Arundo Donax in the Mediterranean region

Nowadays, Invasive Alien Species represent one of the major threats to biodiversity, often contributing to the extinction of native species and to the reduction of ecosystem resilience. Among the most widespread and problematic species, Arundo donax, commonly known as giant reed, has extensively spread throughout the European continent, generating significant ecological impacts. Despite its negative environmental impact, Arundo donax has historically played a significant role in the Mediterranean societies, being a widely available raw material for a broad range of applications, from everyday artifacts to construction purposes. Beyond the manufacture of common objects, this paper investigates its use in traditional construction systems, with particular reference to the Mediterranean context. Its application as a building material is documented through several case studies, while its use persists in certain rural contextes still today. Its extensive exploitation derives from its wide availability, linked to its invasive nature and rapid growth and from its ease of harvesting and workability, its mechanical properties. and its low procurement costs. These characteristics made Arundo donax a highly common construction material in the Mediterranean vernacular architecture, whose culms were extensively employed both as primary construction components and as integrated elements within traditional building systems, fulfilling from structural to finishing functions. Representative examples include the Sardinian baraccas, the traditional settlements of Chebika in Egypt, and the al-mudhif structures of the marshlands of southern Iraq. It was also used to construct individual building elements such as vertical partitions, wall systems, horizontal structures including floors and vaults, suspended ceilings, and roofing systems. The analyzed case studies demonstrate that this plant has historically been employed not merely as a finishing material, but as an actual structural component deeply embedded within local architectural traditions. The examined cases reveal how Arundo donax played a central role in traditional construction systems, effectively integrating environmental, economic, and cultural conditions specific to each territory. The considered examples demonstrate that Arundo donax constituted, throughout the Mediterranean region, the material basis for the development of a shared architectural language. At the same time, this study highlights the contemporary potential of reinterpreting traditional knowledge related to invasive alien species within current debates on sustainable construction, circular material practices, and ecological landscape management.