Response of Spontaneous Plant Communities to Sedum mexicanum Cover and Water Availability in Green Roof Microcosms

Lack of maintenance can lead to ‘weedy’ spontaneous vegetation on green roofs. Aspects roof design, including substrate depth and height, have been shown influence the composition vegetation. In drier climates, Sedum species are often planted shallow ‘extensive’ roofs irrigated during summer maintain cover. However, response cover water availability is unclear. Understanding this relationship could help minimise We hypothesised that increasing (Sedum mexicanum) reduced would reduce abundance, biomass, functional richness, community weighted mean specific leaf area (SLA; CWM by abundance) plant communities. conducted a 10-month experiment in microcosms with S. mexicanum (0%, 25%, 50%, 75% 100% total cover), subjected well-watered or water-deficit irrigation treatment, sown mix 14 commonly occur as measured traits (specific area, dry matter content, relative growth rate), calculated richness. Increasing abundance richness but did not affect biomass. Species was affected interaction watering treatment greatest 0% Increased increased biomass The SLA communities significantly greater treatments where <100%. Therefore, maximising limiting will likely limit diversity Conversely, for left be naturally colonised, encourage establishment increase