12 Mar Aliens and Invasives
With summer in full swing, the Conservation Team at Welgevonden Game Reserve has finished up with the control of the alien and invasive plant species. There is a short window from November to end January to control many of these plants as it needs to be completed before the plants go to seed.
The Conservation Team target small areas by spraying a selective herbicide on the plants in areas which are not too encroached and in heavily encroached areas a tractor is used to dispense herbicide.
You may be wondering why these plants are so bad that they require the use of herbicides? Let’s take a closer look.
Pompom weed, Campuloclinium macrocephalum, is an alien invasive plant from Argentina. It was originally introduced in South Africa as an ornamental flower. While the delicate pinky-purple flowers may be beautiful to look at, they can do striking damage to grasslands and are designed perfectly for the cause. The plant is perennial, dying down in the winter allowing it to escape the frost and fires we experience. In the spring it grows up to 1.5m high. The flowers, perched at the very top, when they turn to seed wind dispersed far and wide. Originating in South America, it has few natural enemies in South Africa. This means it can quickly invade an area and outcompete indigenous species. So, all in all, it is a beautiful nightmare to control.
Lemon bush or Lippia javanica, is actually indigenous to the Waterberg and is even used in traditional medicine. The fragrant leaves and bark can be brewed into a tea said to be effective against fever and as a prophylactic against lung infections. While the shrub is not alien, it is indeed invasive and encroaches heavily on the plains where grazing quality can be severely impacted.
Bankrotbos or Bankrupt bush is also an indigenous invader and the nemesis to game ranchers and livestock farmers throughout the country. Almost three quarters of South Africa’s surface is used for game ranching and livestock. It is estimated that an eighth of this has been infested with bankrupt bush. This woody shrub thrives in disturbed veld and unfortunately, the maintenance of our plains encourages the growth of this plant. Bankrotbos is particularly troublesome as it degrades the veld due to its allelopathic nature. This means the roots produce enzymes which prevent natural grass species from growing
properly! Grasslands are an economical way of feeding game and livestock, this bush directly endangers sustainable grassland production, animal production, food security and biodiversity. It has the power to bankrupt a nation… perhaps this is where the name originates?
Congratulations to the Conservation Team for finishing up the fight against their photosynthetic foe for the season! It is a long and difficult battle, perhaps one that cannot even be won, only mitigated. Whatever the case may be, it will be done to the best of their ability!