Vegetation in Archaeological Areas: Risks, Opportunities, and Guidelines to Preserve or Remove: An Italian Case Study

In the context of research on climate, microclimate, and heritage buildings or museums, archaeological sites represent a unique type of cultural environment. In these settings, the outdoor microclimate is one of the primary factors to consider and manage, both for the preservation of the heritage assets and for the well-being of the visitors. As is well-known, archaeological sites are generally spaces of vegetation colonisation and significant reservoirs of biodiversity. Given that the longevity of a monument is closely tied to its surrounding environment, it is evident that its conservation is significantly influenced by the presence of spontaneous vegetation that colonises it or the designed vegetative structures that surround it. Furthermore, studies have documented that this vegetation is an important factor to consider for the thermal comfort of visitors. In this article, a research methodology is proposed, applied to an Italian case study, in which choices regarding the conservation/removal of the vegetation (roots, leafs, etc.) (Vegetation Hazard Impact Index—VHII) at an archaeological site are examined, along with their impacts on the outdoor microclimate and the thermal comfort of visitors. The findings demonstrate that an approach exclusively focused on removing vegetation deemed invasive risks exacerbating thermal discomfort and, consequently, diminishing the usability of the archaeological site.