Rome has been invaded a fair few times in its long history. (The Gauls, Vandals and Normans, to name a few, led some of the most iconic raids on the Eternal City.) Today, another, more subtle type of invasion is under way — led by invasive species that are posing a threat to some of the city’s historic sites.
A study published last year in Biological Invasions tracked the growth of invasive plants in 26 of Rome's historic sites. The authors compared plant coverage in the 1950s with follow-up studies in 1990, 1995, 2005, and 2019. They found that over time, invasive species have been slowly muscling out the city's native plant life. Beyond that, the study authors also warned that invasive plants are an increasing challenge for the conservation of Rome’s historic sites. “This increase undoubtedly constitutes an alarming threat to the conservation of monuments and possibly even to the conservation of the city’s biodiversity,” the authors’ state.