Environmental studies commissioned to assist in the establishment of the Reserve confirmed that much of the Reserve´s 265 hectares had been severely overrun by alien vegetation. An intensive alien vegetation removal programme is now underway. New laws obligate property owners to remove invasive alien plants on one’s property. Alien vegetation tends to take over rapidly, making it difficult for indigenous vegetation to grow.
This has an impact on birds, animals and other wildlife, and can ultimately threaten the delicate balance of the natural ecosystem. At the same time as alien plants are being removed, indigenous trees and shrubs are being planted to replace them. A large number of indigenous trees (about 15 – 20 different species) have been planted on the Reserve, with more to come. Trees have been labelled and numbered, both for monitoring purposes and for visitor information.
Alien Vegetation – Threats
- Can cause a decline in biodiversity
- Cause changes in faunal composition of an area
- Outcompete indigenous species, often to the point of extinction
- Increase the threat of fire through larger fuel loads and flammable species e.g. Eucalyptus spp.
- Depletion of water resources
- Reduction in land value
- Reduction in tourism and conservation value
- Alteration of the natural soil composition
- Aquatic weeds can cause an oxygen deficiency
- Encourage other pests such as Mosquitoes and snails
- Block sunlight access for other plants, affecting the food chain as a whole
Alien Vegetation – Control
- Mechanical removal of the plants
- Physical removal
- Burning (controlled)
- Chemical control via the use of specific herbicides on various parts of plants and utilizing various methods such as spraying or painting.
- Biological control: The use of the plants´ own natural enemies to combat them
Current Control Programme
Pom pom Weed (Campuloclinium macrocephalum) Very aggressive weed causing severe veld degradation. Control requires foliar application (Herbicide is sprayed onto the leaves of the plant) using Access herbicide and yearly follow up to monitor regrowth.
Black Wattle (Acacia mearnsii) South Africa´s most prominent invader, listed no. 1 on the list of the World´s Worst Invasive Species. Control programme currently combining mechanical and chemical methods through popping trees out by the roots, cut-stump herbicide application and foliar spraying using Confront herbicide.
Legislation Regarding Removal
of Alien Vegetation
Three Categories of alien and invasive species (According to the Conservation of Agricultural Resources Act (CARA) Act 43 of 1983:
Category 1 – Declared weeds:
Prohibited plants, which must be controlled or eradicated (except in dedicated areas) that serve no economic purpose and are possibly harmful to humans, animals and the environment (Bromilow, 2012)1. E.g. Pompom weed (Campuloclinium macrocephalum)
Category 2 – Declared invader plants with a commercial or utility value:
Plants that possess certain useful properties, such as soil stabilisation, fodder etc. “Allowed in demarcated areas under controlled conditions and in biocontrol reserves”(Bromilow, 2012)1. E.g. Black Wattle (Acacie mearnsii)
Category 3 – Mostly ornamental plants:
Proven invaders, of which no further planting is allowed, except with special permission, and trade in propagative material is prohibited. “Existing plants may remain (except those within the flood line of watercourses or wetlands or as directed by the executive officer) but must be prevented from spreading” (Bromilow, 2012)1. E.g. Jacaranda (Jacaranda mimosifolia)