Ecological types and bioindicator macrophyte species of pollution of riparian vegetation of Oued Lârbaa in Taza City of Morocco.

The object of our study is devoted to the Spermatophyta of the wetlands of Oued Lârbaa, the main river of the city of Taza, Morocco, and which is under strong anthropic pressure. Our work involved a floristic inventory, to define ecological types and groups of dominant plants in relation to seasonal factors and types of pollution, explaining the meaning of their presence. For this purpose, floristic sampling was carried out along the Oued during the dry periods (2017 and 2018) and the wet period (2018). A total of 66 plant species belonging to 54 genera and 30 families were identified, including 44 species during the wet period (2018) and 27 species during the dry periods (2017 and 2018). This difference is due to the favorable conditions for vegetation development during the period of precipitation and to the increase in pollution rates during the dry season. The inventoried flora shows the dominance of 10 ecological types characterized by the following plants: Cynodon dactylon, Arundo donax, Olea europaea, and Tamarix gallica (common between the two periods); Dittrichia viscosa, Visnaga daucoides, Typha angustifolia, and Ricinus communis (during the dry periods of 2017 and 2018); and Juncus maritimus and Populus nigra (during the wet period of 2018). The ecological types identified in this work decrease from the dry season to the rainy season, while specific richness increases. These dominant plants are all considered as bioindicators of the presence of heavy metals.