Cultural heritage sites such as historical or sacred areas provide suitable habitats for plants and play an important role in nature conservation, particularly in human-modified contexts such as urban environments. However, such sites also provide opportunities for the spread of invasive species, whose impact on monuments has been raising growing concerns. The aim of this study was to investigate the patterns of distribution and spread of invasive plants in heritage areas, taking the city of Rome as an example. We focused on woody species as they pose the greatest threat to the conservation of monuments, owing to the detrimental effects of their root system. We analysed changes in the diversity and traits of native and non-native flora growing on the walls of 26 ancient sites that have been surveyed repeatedly since the 1940s. We found that the diversity of the native flora has steadily decreased, while there has been an increase in non-native, larger and more damaging species. The introduced species that have expanded most are ornamental wind- or bird-dispersed trees, which represent a major management problem as their propagules can reach the upper sections of the monuments, where they become more difficult to control. The most widespread and damaging of such species is Ailanthus altissima, which has recently been included among the invasive species of European Union concern (EU Regulation 2019/1262). Our findings show that plant invasion is an emerging challenge for the conservation of heritage sites and needs to be prioritized for management to prevent future expansion.

历史或圣地等文化遗产遗址为植物提供了合适的栖息地，并在自然保护中发挥着重要作用，特别是在诸如城市环境等人类改造的环境中。但是，这些场所也为入侵物种的传播提供了机会，入侵物种对古迹的影响引起了越来越多的关注。这项研究的目的是，以罗马市为例，研究入侵植物在传统地区的分布和传播方式。我们重点研究木本物种，因为其根系的有害影响，它们对古迹保护构成最大的威胁。我们分析了自1940年代以来反复进行调查的26个古代遗址的墙壁上生长的本地和非本地植物区系多样性和特征的变化。我们发现，本地植物区系的多样性一直在下降，而非本地，更大和更具破坏性的物种却有所增加。引入最多的物种是观赏风或鸟类分散的树木，这是一个主要的管理问题，因为它们的繁殖体可以到达古迹的上部，在那里它们变得更加难以控制。这种物种最广泛和最具破坏力的是臭椿（Ailanthus altissima）最近已被纳入欧盟关注的入侵物种之列（欧盟法规2019/1262）。我们的研究结果表明，植物入侵是遗产保护的新兴挑战，需要优先进行管理以防止将来的扩展。