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Organized Oral Session

Session: : Green Roof Plant Community Function and Associated Drivers

OOS 15-4 - Trait-Environment Responses of Spontaneous Vegetation on Green Roofs: A Global Study

Tuesday, August 8, 2023
8:45 AM – 9:00 AM PDT
Location: 256
This study investigates the impact of green roof characteristics on the assembly of spontaneous vegetation communities, accounting for the influence of species traits and phylogenetic relationships. The research data was collected from 192 green roofs in 11 countries globally, including surveys of vegetation and assessments of environmental, maintenance, and design characteristics. To focus on spontaneous species, surveys that could differentiate between spontaneous and planted species were selected, resulting in the identification of 117 spontaneous species. To understand the relationship between green roof characteristics and spontaneous plant community assembly, the study extracted trait data representative of plant ecological strategies from the TRY database for identified spontaneous species. Traits that were easy to measure and available for most species identified in surveys were the focus of analysis.

A Hierarchical Modelling of Species Communities (HMSC) approach was used to examine the connection between spontaneous species traits and environmental factors that influence community assembly. The model demonstrated strong explanatory power with an AUC value of 0.92. In addition, its predictive power was assessed through a fourfold cross-validation, resulting in an AUC value of 0.76. These results suggest that the model is effective at explaining the data and can make reasonably accurate predictions.

The study revealed negative associations between the intercept of green roof environmental characteristics and biennial and perennial lifecycles, while a positive relationship was observed with specific leaf area (SLA). Low maintenance green roofs had a negative association with SLA, but a positive correlation with the intercept of spontaneous species traits. Aridity was positively linked with biennial and perennial lifecycles and negatively associated with seed mass. By providing insights into the factors that influence spontaneous plant communities on green roofs, this research can help guide resilient green roof design and trait-based plant selection. The findings of this study are relevant to professionals involved in green roof design and management, as well as those interested in understanding the drivers of plant community assembly more broadly.