Vascular plants census linked to the biodeterioration process of the Portuguese city of Mazagan in El Jadida, Morocco

Abstract

Built in the early XVIth century, Mazagan is one of the first fortifications constructed in North Africa by Portuguese explorers on their way to India. Among the factors of degradation facing the Portuguese city, we were particularly interested in the action of plants that develop there. The objective of our study is to establish a list of plant species that develop on materials and to analyze the potential effects of that vegetation on substrate and thus on monument deterioration. We carried out a systematic sampling in Mazagan. After sampling and identification of plants, we established a list of 57 species belonging to 25 families and 54 genera. The Asteraceae family is the richest in species. The therophytes are the most represented in Mazagan with a proportion of nearly 53% followed by Hemicryptophytes that contain nearly 26% of the listed species. These two biological types may have a fasciculated or pivotal rooting that sinks into the substrate leading to its crumbling. Other biological types such as phanerophytes, chamaephytes and geophytes are no less harmful even if they are represented only in a small proportion: their generally pivoting roots destroy the substrate more quickly. The study site is colonized mainly by spontaneous plants, which represent nearly 81%. Naturalized plants like Lycium europaeum have become so invasive that they even settle on the side of walls. Maintenance measures must be undertaken in the city to control the spread of such destructive vegetation.