Citation: Fracchiolla, M.; Lasorella, C.; Cazzato, E.; Vurro, M. Weeds in Non-Agricultural Areas: How to Evaluate the Impact? A Preliminary Case Study in Archaeological Sites. Agronomy 2022, 12, 1079. https:// doi.org/10.3390/agronomy12051079 Academic Editor: Anestis Karkanis Received: 28 March 2022 Accepted: 28 April 2022 Published: 29 April 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). agronomy Article Weeds in Non-Agricultural Areas: How to Evaluate the Impact? A Preliminary Case Study in Archaeological Sites Mariano Fracchiolla 1, * , Cesare Lasorella 1 , Eugenio Cazzato 1 and Maurizio Vurro 2 1 Department of Agricultural and Environmental Science, University of Bari, Via Orabona 4, 70126 Bari, Italy; cesare.lasorella@uniba.it (C.L.); eugenio.cazzato@uniba.it (E.C.) 2 Institute of Sciences of Food Production (ISPA), National Research Council (CNR), Via Amendola 122/O, 70125 Bari, Italy; maurizio.vurro@ispa.cnr.it * Correspondence: mariano.fracchiolla@uniba.it Abstract: 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. Keywords: weed management; Hazard Index; Hazard Value; weed survey 1. Introduction The term “weeds” refers to “plants suitable for habitats modified by man and that interfere with human activities” [1]. It implies an anthropocentric rather than an ecolog- ical vision [2], since the existence and the characteristic of the interference depend on men’s purposes. Interference leads to a hazard with associated damage, and it is rarely related to a single species or individual, but to a “weed community”, defined as “a set of individuals found in a survey at a given instant and in a physically delimited space” [3]. In agroecosystems, the main hazards related to the weeds are due to the competition with crops, mainly affected by the time of emergence, the density of plants, and the traits of the species [4]. The resulting damages are precisely quantifiable because they concern the yield, which is a quantitative variable. In non-agricultural areas, they involve general considerations, such as unsightliness, functional damage, and public health [5]. Agronomy 2022, 12, 1079. https://doi.org/10.3390/agronomy12051079 https://www.mdpi.com/journal/agronomy