Preventing invasion of exotic species into urban forests is important for sustaining native species diversity. In Japan, Ligustrum lucidum, an invasive tree, has become widespread in urban areas. Here, we investigated the spread of L. lucidum in a semi-natural, urban shrine forest to infer which native species’ preferred habitats may be affected. L. lucidum was most abundant near the artificially created forest edge where canopy trees are pruned regularly. Spatial distribution of L. lucidum overlapped with those of two native species (Cinnamomum japonicum, Quercus glauca), but was segregated from the other three native species. We also compared leaf functional traits between L. lucidum and the native species to infer functional niche overlap. L. lucidum exhibited greater plasticity of leaf functional traits compared to native species and its leaf functional traits were similar with Ci. japonicum, Ilex rotunda and Q. glauca, but not with Camelia japonica and Ternstroemia gymnanthera. Our results suggest that, currently, the preferred habitat and realized functional niche of L. lucidum overlaps with those of Ci. japonicum and Q. glauca. High plasticity of leaf functional traits contributing to shade tolerance may allow L. lucidum to expand its spatial distribution in this forest, affecting other native species in the future. Our results emphasize the importance of removing invasive species during early stages of invasion while their distribution is still relatively confined and negative effects on native species are limited.

防止外来物种入侵城市森林对于维持本地物种多样性非常重要。在日本，女贞是一种入侵树木，已在城市地区广泛传播。在这里，我们调查了灵芝在半天然的城市神社森林中的传播，以推断哪些本地物种的首选栖息地可能会受到影响。L. lucidum在人工创造的森林边缘附近最为丰富，在那里经常修剪树冠。灵芝的空间分布与两种本地物种（Cinnamomum japonicum、Quercus glauca）的空间分布重叠，但与其他三种本地物种分离。我们还比较了两者之间的叶功能性状L. lucidum和本地物种推断功能生态位重叠。灵芝叶片功能性状的可塑性比本地种大，叶片功能性状与Ci相似。japonicum、Ilex rotunda和Q. glauca，但不与Camelia japonica和Ternstroemia glauca 一起使用。我们的结果表明，目前，灵芝的首选栖息地和已实现的功能生态位与Ci重叠。japonicum和Q. glauca。有助于耐荫性的叶功能性状的高可塑性可能允许灵芝扩大其在这片森林中的空间分布，在未来影响其他本地物种。我们的结果强调了在入侵的早期阶段清除入侵物种的重要性，而它们的分布仍然相对有限，对本地物种的负面影响有限。