Grant: Research Tools and Instruments - Category 1 (<$150,000)

Green roofs represent an engineered ecosystem that provides many benefits to human society. Green roofs reduce roof temperatures in summer, and reduce storm runoff into sewer systems. Despite recent interest in constructing green roofs across Canada, there is little understanding of how different plant species contribute to the benefits of rooftop ecosystems. My students and I have established a green roof research facility that allows us to quantify the benefits of green roofs compared to conventional roofs, and to evaluate the relative performance of different types of plants. We are requesting a portable photosynthesis unit to measure water vapor released by plant leaves and the rate of carbon uptake. These measures will allow us to understand how plants are responding to the growing conditions on the roof at different times of the year. Water uptake and release by plants drive roof cooling and the roof's ability to retain water after storms. Plants that use little water may survive better in the shallow soils on green roofs, but do not perform cooling and water capture functions as well as other species. The portable photosynthesis unit will allow us to evaluate this trade-off between drought tolerance and performance of green roof ecosystem services. The data collected with the portable photosynthesis unit will allow me and my students to make informed choices about plants for green roof applications, to create mixtures of species that perform well at different times of the year to maximize year-round benefits, and to discover the links between plant physiology and the useful functions of green roof ecosystems. While each plant species is unique, they can be put into groups with similar functions. While we have already tested over 30 species native to Atlantic Canada on our experimental roofs, quantifying basic physiological performance of these species using the photosynthesis unit will allow us to group species by function. Understanding how general plant traits relate to green roof functioning will allow us to predict the performance of other plants we have not yet tested for application across Canada.