Green roof invertebrate biodiversity

Green roofs were designed by civil engineers to insulate buildings, protect buildings from ultraviolet light, and slow stormwater runoff. However, from a biologist’s perspective they are an untapped resource for growing crops and native plants that support pollinators. Two basic assumptions about green roofs are (1) that they provide more habitat for invertebrates than normal roofs, and (2) that approach the same level of biodiversity as ground level sites. The first assumption is so basic that it has rarely been tested. We compared biodiversity on a green roof composed of plants from a commonly used genus in the green roof industry, sedums, with biodiversity on an asphalt tile roof. To test the second assumption we compared biodiversity on a green roof of plants that contained a mix of native and nonnative plants to ground level sites in the immediate vicinity. Surprisingly, invertebrate biodiversity on a sedum roof was not different from that of an asphalt tile roof containing no vegetation. Biodiversity on the mixed native plant green roof did, however, approach similar levels of biodiversity to nearby ground level sites. We conclude that for green roofs to be functional from both engineering and biological perspectives, they must include a diverse array of plants. We are now testing a variety of native plants from Utah to determine their suitability for green roof installations. The data are limited to 2014 and include two separate sites: the greenroof-asphalt roof paired sites at Southern Utah University in Cedar City, Iron County, Utah, and the greenroof-ground level paired sites at the University of Utah, Salt Lake City, Salt Lake County, Utah. https://www.hydroshare.org/resource/a7821bceca9e42159790d5e1d1441c8c