Occurrence, distribution and potential ecological impact of invasive alien plants at Baixo Limpopo irrigation scheme, Mozambique

In Mozambique, the invasive alien plants (IAPs) have been introduced over the years most of them deliberately or accidentally. Studies that report the occurrence, distribution and ecological impact upon native plant diversity are very few. In order to contribute for this knowledge, a study was conducted to survey IAPs and to assess their associated impacts on native species. The samplings were taken along the Limpopo River, channels and drainage ditches, in every 2 km. The abundance and coverage of the species was determined using a quadrat of 1 m2. Species identification was performed by botanical and field guides. The ecological impact was evaluated by the generic impact scoring system. The data were analyzed using Excel and R. The ArcGIS 10.3 software was used to create IAPs location map. The results of this survey indicated that a total of 191 identified plant species, 71 IAPs (74.65% terrestrial and 25.35% aquatic) belonging to 29 families occur in this area. The Poaceae and Asteraceae families were the most represented in invasive species. The most abundant species were Phragmites australis, Phragmites mauritianus and Echinochloa pyramidalis. Our observations indicate that there is an increasing number of IAPs at study area, and most of them have a restricted distribution (40.28%). Our study findings suggest that in the agricultural production areas, especially in Xai-Xai, the enrichment of water courses with nutrients is contributing to both the increase and growth of IAPs. These results are emphasizing the need to start planning the action measures.