Epsilon Archive for Student Projects

Abstract

As urbanization and climate change intensify the Urban Heat Island (UHI) effect, extensive green roofs have become crucial nature-based solutions for urban climate adaptation. However, contemporary thin-substrate green roofs predominantly rely on low-diversity succulent monocultures (e.g. Sedum spp.). While these systems survive in shallow substrates, their limited structural and functional diversity constrains their ecological potential and long-term resilience under increasingly extreme weather events. This thesis investigates an alternative approach: the integration of Mediterranean garrigue vegetation into thin-substrate green roofs to enhance climatic resilience and ecosystem multifunctionality.
Employing a mixed-methods approach, this research combines a review of climate analogue modelling studies, microclimate aspects, a literature study and qualitative evaluations of both a built case study and natural reference landscapes. This process informs a trait-based plant selection framework grounded in the habitat template approach. The findings demonstrate that both long-term regional climate shifts and the immediate, extreme abiotic stressors of the rooftop microclimate justify the use of drought-adapted Mediterranean xerophytes in temperate urban contexts.
To successfully operationalize the garrigue biome on a roof, the design translates its physical and functional complexity rather than relying on simple taxonomic replication. A conceptual design framework is proposed, e.g. combining variable substrate depths and microtopography. By integrating physical facilitators and maximizing phylogenetic and life-form diversity, the framework supports a resilient, rhythmic matrix of subshrubs, succulents, grasses and forbs.
The plant selection process utilized a systematic, trait-based screening framework to filter a comprehensive pool of ecosystem-associated species against criteria of functional and ecological traits. The design process then translated this curated vegetation palette into a modular green roof prototype that mimics the structural complexity of the natural reference habitat. By grounding these findings in a physical layout, this prototype proves that theoretical ecological concepts can be successfully translated into a functional spatial reality. Ultimately, this research provides landscape architects with an actionable, transferable design methodology, demonstrating how extensive green roofs could evolve into complex, multi-layered ‘rooftop garrigues’ capable of sustaining vital ecosystem services in a changing climate.