Weeds in Non-Agricultural Areas: How to Evaluate the Impact? A Preliminary Case Study in Archaeological Sites

The term “weeds” refers to “plants suitable for habitats modified by man and that interfere with human activities”. It implies an anthropocentric rather than an ecological vision since the existence and the characteristic of the interference depends on men’s purposes. In the archaeological sites, the most important damage is the functional one and it ranges from hazards for the structures to the interference that weed flora can exert on the technical management and fruition of the site. In this particular type of environment, the diverse methods available to quantify the magnitude of the infestation are not sufficient to describe the potential or actual hazard to which a given infested site is subjected. Therefore, it is necessary to consider a greater degree of detail (including morphological, ecological, and physiological properties of the weeds) and to keep them all in consideration. The aim of the present work was to try to identify and propose a method for the assessment of the hazards and thus the damages that a weed community can lead in sites of historical and archaeological interest. The procedure quantifies the degree of the infestation, in terms of occurring species, quantifies the related hazard based on some traits of the weed species, and calculates indexes capable of providing synthetic and comparable information on the hazard to which the site is exposed. The proposed method was applied and tested in some sites of archaeological interest in the Apulia Region, in southern Italy. Applied to the surveyed archaeological sites, the proposed Indexes revealed the presence of weed infestations variously assorted in terms of potential damage, generating different hazard scores. This confirms the importance of understanding the type of infestation and not only its extent. In this study, a procedure was provided that can support decision-makers. Although studied for archaeological sites, the same principles adopted in this procedure could be proposed for other non-agricultural areas