Do Wetland Vascular Plants Introduced in Morocco Also Become Invasive?

Abstract

The propagation of exotic species is a complex process influenced by taxa-specific factors, in addition to climate and anthropozoogenic activities. However, the introduction of plants outside their native range does not always lead to their naturalization and/or the invasion of native ecosystems. Once non-native species have become established, they become extremely difficult to eradicate or control. Moroccan wetlands are crucial to the conservation of biodiversity, but they are susceptible to invasive hygrophilous plants. The invasive potential of introduced hygrophytes in Morocco was assessed through an extensive documentation review on their distribution, biology, ecology, uses, considering both their updated scientific names and their synonymy. Three groups of hygrophytes with varying invasive potential have been identified, based on their bioclimatic distribution, intrinsic propagation ability and use. The high invasiveness group (species with high invasiveness in other countries) includes Populus nigra L., P. alba L., Cotula coronopifolia L., Gomphocarpus fruticosus (L.) W.T. Aiton, and Arundo donax L. With the exception of Cotula coronopifolia, which is naturalized in Morocco, none of other highly invasive in other countries species has reached naturalized and/or invasive status. The status of these introduced hygrophytes in Morocco, as well as those with moderate (Heliotropium curassavicum L., Cotula anthemoides L., Pistia stratiotes L., Cyperus eragrostis Lam., and Paspalum distichum L.) or low invasive potential [Azolla filiculoides Lam., Modiola caroliniana (L.) G. Don, Salix babylonica L., Asclepias curassavica L., Eclipta prostrata (L.) L., Triglochin striata Ruiz & Pav., and Eichhornia crassipes (Mart.) Solms], is compared with that of other regions of the world. Although Pistia stratiotes has invaded wetlands in several regions, its invasion is currently limited in Morocco due to environmental and management factors. As a result, more botanical studies of Moroccan wetlands are needed, as many introduced species are currently poorly known and their status may change, while new introduced hygrophytes may also be encountered. Assessing the invasive potential of introduced hygrophytes will enable in part the implementation of proactive measures to better protect local wetlands against invasive species.