title: Plant performance on Mediterranean green roofs: interaction of species-specific hydraulic strategies and substrate water relations.
abstract: Recent studies have highlighted the ecological, economic and social benefits assured by green roof technology to urban areas. However, green roofs are very hostile environments for plant growth because of shallow substrate depths, high temperatures and irradiance and wind exposure. This study provides experimental evidence for the importance of accurate selection of plant species and substrates for implementing green roofs in hot and arid regions, like the Mediterranean area. Experiments were performed on two shrub species (Arbutus unedo L. and Salvia officinalis L.) grown in green roof experimental modules with two substrates slightly differing in their water retention properties, as derived from moisture release curves. Physiological measurements were performed on both well-watered and drought-stressed plants. Gas exchange, leaf and xylem water potential and also plant hydraulic conductance were measured at different time intervals following the last irrigation. The substrate type significantly affected water status. Arbutus unedo and S. officinalis showed different hydraulic responses to drought stress, with the former species being substantially isohydric and the latter one anisohydric. Both A. unedo and S. officinalis were found to be suitable species for green roofs in the Mediterranean area. However, our data suggest that appropriate choice of substrate is key to the success of green roof installations in arid environments, especially if anisohydric species are employed.
authors.affiliation: Dipartimento di Scienze Biologiche ed Ambientali, Università di Messina, via F. Stagno D'Alcontres 31, 98166 Messina, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Raimondo
authors.affiliation: Dipartimento di Scienze Biologiche ed Ambientali, Università di Messina, via F. Stagno D'Alcontres 31, 98166 Messina, Italy ptrifilo@unime.it.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Trifilò
authors.affiliation: Dipartimento di Scienze Biologiche ed Ambientali, Università di Messina, via F. Stagno D'Alcontres 31, 98166 Messina, Italy.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Lo Gullo
authors.affiliation: Harpo seic verdepensile, Via Torino 34, 34123 Trieste, Italy.
authors.forename: Sergio
authors.initials: S
authors.lastname: Andri
authors.affiliation: Dipartimento di Scienze della Vita, Università di Trieste, via L. Giorgieri 10, 34127 Trieste, Italy.
authors.forename: Tadeja
authors.initials: T
authors.lastname: Savi
authors.affiliation: Dipartimento di Scienze della Vita, Università di Trieste, via L. Giorgieri 10, 34127 Trieste, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Nardini
keywords: Anisohydric; Mediterranean region; arbutus; drought stress; green roof; isohydric; sage