The Negative Effects Of Alien And Invasive Species

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Introduction
Alien and invasive plants (AIPs), classified as biological invaders, negatively affect water sources as (Ghahramanzadeh, 2013). The NEMBA Alien and Invasive Species Regulations (Notice number 864 of 29 July 2016 in Government Gazette 40166) aim to: Prevent the unauthorised introduction and spread of alien and invasive species to ecosystems and habitats where they do not naturally occur, Manage and control alien and invasive species, to prevent or minimise harm to the environment and biodiversity; and Eradicate alien and invasive species from ecosystems and habitats where they may harm such ecosystems or habitats.

The NEMBA Alien and Invasive Species Regulations further categorise the various invasive species, as listed in the National List of Invasive Species, as falling within Category 1a, 1b, 2 and 3.

AIPs in South Africa cover a vast area of the land surface and is continuing to spread at a rapid pace (Blanchard & Blignaut, 2011). Woody AIPs negatively and certain areas detrimentally affect biodiversity especially faunal and floral Species of Conservational Concern (SCC), water sources, land use and productivity (Mugido et al., 2014). Some of the woody species include but not limit to Acacia mearnsii (Black Wattle), Acacia saligna, Eucalyptus sp. These species have a total evaporation (TE) of 895 mm in the Western Cape. The native and indigenous vegetation, in contrast, have an TE of 520 mm (fynbos) and TE of 575 mm (thickets), this indicates that AIPs use more water than native vegetation to the area does (Meijninger & Jarmain, 2014). Van Wilgen, Cowling and Burgers (1996) estimated a 30% loss of water supply to the City of Cape because of the increased AIPs proliferation and the increase usage of water by these AIPs. Controlling of AIPs within the catchment area of the water supply could have lessened the water shortage that the City of Cape Town is experiencing currently. The invasion of AIPs is a severe threat to the sustainability of agricultural activities, which are water intensive. This is not limited to the agricultural sector, but also includes other industries using water as one of their key inputs. AIPs proliferation has both economic and environmental implications (Lenda,
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