Climate and plant traits as influences on green roof performance

Abstract

Green roofs are being introduced and installed in varying climates worldwide to benefit from green roof services. Services of thermal cooling and stormwater capture reduce building energy consumption and strain on infrastucture. Across North America, green roofs often make use of a limited set of plants, but the effects of different climates on survival and growth are unknown while survival often outranks optimization of services. To identify the impact of climate on plant performance, I installed an identical green roof system in three Canadian cities. To investigate the relationship between plant traits and green roof services, I measured service provision and analyzed for correlation. A moderate climate supported the best growth and performance, but in all climates, mixture plantings performed well over the two growing seasons. Plant traits of specific leaf area and plant height were predictive, through vegetation characteristics, of stormwater capture and green roof surface cooling.