Cities are human dominated ecosystems providing novel conditions for organisms. Research on urban biodiversity is rapidly increasing, yet it is still hampered by the partial spatial coverage of cities and because of existing taxonomic biases. Predictive models have proved to be a key tool to solve this shortfall. However, predictive models have rarely been used in urban ecosystems due to either the lack of sufficient species records or high-quality predictors (e.g. meaningful ecological maps). Here, we assemble a large cross-taxa inventory of 1446 species from 12 taxonomic groups, including several understudied invertebrate groups, sampled in 251 sites in Zürich, Switzerland. We investigate the species diversity distributions and the structure of species assemblages along artificial urban ecological gradients by applying predictive models. We find that the general species diversity distribution law, where assemblages are dominated by a few very abundant and frequent species, applied consistently across all taxonomic groups (3% of the species accounting for approximately 50% of abundance). Furthermore, only species of intermediate abundance and frequency are spatially structured along urban intensity gradients, with rare species numbers keeping constant even in the most urbanised parts of the city. In addition, we show that green areas with low mowing regimes are associated with higher species diversity in the majority of taxonomic groups. Hence, this suggests management relaxation as a low-cost solution to promote species richness. Our study demonstrates the potential of predictive modelling for addressing ecological questions in urban environments and to inform management and planning.

城市是人类主导的生态系统，为生物提供了新条件。关于城市生物多样性的研究正在迅速增加，但由于部分空间覆盖城市以及现有的分类学偏见，仍然受到阻碍。事实证明，预测模型是解决这一不足的关键工具。然而，由于缺乏足够的物种记录或高质量的预测因子（例如有意义的生态图），预测模型很少用于城市生态系统。在这里，我们收集了来自12个生物分类群的1446种大型跨类群清单，其中包括几个未被充分研究的无脊椎动物群，它们在瑞士的苏黎世251个地点进行了采样。我们通过应用预测模型调查沿人工城市生态梯度的物种多样性分布和物种集合的结构。我们发现，一般的物种多样性分布定律在几个分类学组中始终如一地适用（其中3％的物种约占50％的丰度），该组合由少数几个非常丰富和频繁的物种主导。此外，只有中等丰度和频率的物种才沿着城市强度梯度在空间上结构化，即使在城市中城市化程度最高的地区，稀有物种的数量也保持不变。此外，我们显示，在大多数分类学类别中，低割草制度的绿地与较高的物种多样性有关。因此，这表明管理放松是促进物种丰富度的低成本解决方案。