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.

绿色屋顶（green roof）由土木工程师设计，旨在为建筑隔热、抵御紫外线辐射，并延缓雨水径流。然而从生物学家的视角来看，绿色屋顶是一片未被充分开发的资源，可用于种植助力传粉者的农作物与本土植物。针对绿色屋顶存在两项核心假设：其一，绿色屋顶可为无脊椎动物（invertebrate）提供比普通屋顶更多的栖息空间；其二，绿色屋顶的生物多样性（biodiversity）水平可与地面生境持平。第一项假设过于基础，因此极少得到实证检验。我们以绿色屋顶产业中常用的景天属（sedum）植物构建试验绿色屋顶，并将其生物多样性水平与沥青瓦屋顶进行了对比。为验证第二项假设，我们将搭配本土与外来植物混合种植的绿色屋顶的生物多样性，与周边紧邻的地面生境进行了对比。令人意外的是，景天属植物绿色屋顶的无脊椎动物生物多样性，与无植被覆盖的沥青瓦屋顶并无显著差异。但搭配本土与外来植物混合种植的绿色屋顶，其生物多样性水平与周边地面生境已趋于一致。综上，若要让绿色屋顶同时满足工程与生物学层面的功能需求，必须配置种类丰富的植物群落。目前我们正针对犹他州本土的多种植物开展试验，以评估其适配绿色屋顶安装的可行性。本数据集仅涵盖2014年的数据，包含两处独立采样点：一处位于犹他州艾恩县锡达城的南犹他大学，为绿色屋顶-沥青瓦屋顶配对采样点；另一处位于犹他州盐湖县盐湖城的犹他大学，为绿色屋顶-地面生境配对采样点。