FLORISTIC DIVERSITY AND ITS BIODETERIOGENIC EFFECT ON THE ARCHAEOLOGICAL SITE OF VOLUBILIS (MOROCCO)

The objective of this study is to list the plant species colonizing the archaeological site of Volubilis in Morocco, in order to determine their ecological importance and their impact of biodeterioration. The site is located about twenty kilometers north of Meknes on an area of ​​42 ha. We have inventoried 94 species belonging to 33 families of higher plants. The sampling was carried out across the site using 4 transects with 3 types of surveys each respectively on the walls, on the joints of the paving and on the outcrops of the bedrock. To compare the transects, we used the Sørensen similarity index. The transects taken in pairs show indices above 50% and, grouped together, an index of 78%. This great similarity between the transects is undoubtedly the result of the evolution of the vegetation under globally quite homogeneous conditions. However, some surveys show weak similarity: 34% between R1 and R2, 18% between R1 and R3 and 14% between R2 and R3. This means a change in the floristic procession and a different vegetation dynamic on the wall surface (R1), on the joints of the paving (R2) and on the bedrock outcrops (R3). The vascular flora of the Volubilis site presents an undeniable biodeteriogenic action, in particular through the phenomenon of cracking due to the action of the roots on the various supports. This mechanical action is further accentuated by combining with the chemical action of dissolution of the materials by the acids secreted by the roots.