Landscape and Irrigation is read by decision makers throughout the landscape and irrigation markets — including contractors, landscape architects, professional grounds managers, and irrigation and water mgmt companies and reaches the entire spetrum.
Issue link: http://read.dmtmag.com/i/626548
www.landscapeirrigation.com Landscape and Irrigation January/February 2016 13 CASE STUDY associates worked closely with faculty at SUNY ESF, including Distinguished Teaching Professor of Environmental and Forest Biology, Don Leopold (author of Native Plants of the Northeast: A Guide for Gardening and Conservation and Trees of New York: Native and Naturalized) and Associate Professor of Landscape Architecture, Timothy Toland, who specializes in sustainability and holistic systems design. In thinking about the conditions that are typical for a rooftop garden, and in their case a west-facing one, the Andropogon/ SUNY ESF team recognized that it needed plants that would endure extremes of temperature, wind and moisture. To minimize future maintenance, the team sought plants that can tolerate low soil fertility/low organic matter and shallow soils. Drought tolerance was also key, as the intent was to have the plants function as they would in their native environment, without any supplemental irrigation. The team chose two natural plant communities adapted to these very conditions: the Eastern Ontario Dune community, a windy and dry habitat extending 17 miles along Lake Ontario, and the Alvar Pavement Barren community, found in limited pockets north of the Great Lake Dunes, to the northwest of Watertown, N.Y. Alvar community plants grow in low-fertility soil with a high pH and, despite the shallow soils they inhabit, tolerate the drought of summer but also the seasonal wetness of spring. With these communities, the team found an ideal match for the rooftop conditions. It would be no small feat to responsibly source these plants — some of which grow natively only in the Eastern Ontario Dune and Alvar Pavement Barren ecosystems. Motherplants Ltd., a green roof plants specialty grower now based out of Princeton, Ontario (then based out of Ithaca, N.Y.) was contracted to propagate and procure the plants. But first, the design team and SUNY ESF faculty developed a set of rigorous plant trial protocols, and constructed a series of test frames on an adjacent building roof to mimic growing conditions. (Carlisle SynTec donated materials for the initial test frames.) "The group as a whole was fairly confident that the plants would perform well, but the design team needed to validate that we could deliver a successful and sustainable design solution to the client," said Damone. In 2010, Leopold and colleagues obtained cuttings, seeds and plugs, and involved students in research involving planting each species at varying soil depth, media and spacing. They collected three seasons of data, which gave evidence that plants from these specific plant communities did well in this specific unirrigated, rooftop environment. The Andropogon Associates planting plan called for the Eastern Ontario Dune plant community to be sited on three sides of the green roof perimeter. Dune plants that are thriving there include American beach grass (Ammophila breviligulata), Canada wild rye (Elymus Canadensis) and the heartleaf willow (Salix cordata). The internal, more protected beds are populated with the Alvar community plants, which include hairy beardtongue (Penstemon hirsutus), golden alexanders (Zizia aurea), northern prairie dropseed (Sporobolus heterolepis), smooth rose (Rosa blanda) and various sedges (Carex spp.). Left: Bringing in the growing medium for the new green roof. Photo courtesy Recover Green Roofs (recovergreenroofs.com). Right: Planting the new SUNY ESF Gateway Center green roof, using jute to prevent the planting medium from eroding. Photo courtesy Recover Green Roofs