Green roofs are urban design elements providing ecosystem services in cities, yet little is understood about how to plan for their biodiversity and conservation outcomes. Using both green roof practitioner and ecological knowledge as a guide, this study examined how well we can predict the relationships between plant species richness and the characteristics of green roofs. Forty-two roofs in three U.S. cities (Chicago, Cleveland, and Minneapolis) were surveyed for plant species richness, soil characteristics, plant cover, maintenance, age, and area. Results indicate practitioner and ecological assumptions were approximately equally accurate in predicting relationships, but neither set of assumptions was particularly reliable. Diversity differed between cities, and plant communities on intensive roofs were more diverse than on extensive roofs. Plant diversity on intensive roofs was also more responsive to soil texture, area, and fertilizer use, when compared to extensive roofs. Intensive roofs may be more responsive to variables due to substrate depth increasing potential plant diversity, coupled with a wider variability in design intentions than is typical for extensive roofs. While the two knowledge bases influencing green roof understanding are a good starting point to explain green roof dynamics, new classifications (beyond extensive and intensive roofs) could help bridge the gap between practitioner and ecological knowledge and aid in predicting patterns by emphasizing green roof design intent rather than substrate depth. Our study indicates that using scientific research to further examine green roof landscapes is necessary for improving the accuracy and generalizability of predictions derived from both applied practitioner knowledge and ecological theory.

绿化屋顶是在城市中提供生态系统服务的城市设计元素，但对于如何规划其生物多样性和保护成果知之甚少。本研究以绿色屋顶实践者和生态知识为指导，研究了我们如何很好地预测植物物种丰富度与绿色屋顶特征之间的关系。调查了美国三个城市（芝加哥，克利夫兰和明尼阿波利斯）的42个屋顶的植物物种丰富度，土壤特性，植物覆盖率，维护，年龄和面积。结果表明，从业人员和生态学假设在预测关系方面大致相同，但是这两组假设都不是特别可靠。城市之间的多样性不同，密集屋顶上的植物群落比广阔屋顶上的植物群落更加多样化。与宽阔的屋顶相比，高强度屋顶上的植物多样性对土壤质地，面积和肥料的使用也有更强的响应能力。由于底物深度增加潜在的植物多样性，并且集约化设计的可变性比大集聚型屋顶的典型变化更大，因此集约化屋顶可能对变量更敏感。虽然影响绿色屋顶理解的两个知识库是解释绿色屋顶动态的一个很好的起点，但新的分类（除了广泛和密集的屋顶之外）可以帮助从业者和生态知识之间架起桥梁，并通过强调绿色屋顶的设计意图来帮助预测模式。而不是基板深度。