Bush Encroachment: Johan Joubert
Bush Encroachment:
Johan Joubert
Impact of Bush encroachment: The impact what it have on veld can be ilistrated as such:
In an area of 300ha there could be 23 head of catttle with 20 calfs, based on the asumption that there is a 20%
growth.
If Bush encroachment is not managed, the head of cattle would decrease to 22 the next year, together decreasing in calf numbers.
This routine would repead itself every year, resulting in a downwords trend in the amount of cattle.
The opposite would occour if bush encroachment have been managed from the start. The amount of cattle
would increase, and the amount of calves. (Siee Tabel 1).
Acacia mellifera ( Swarthaak ), rootsistem in the top soil layers, extracting water like a “windmill”
Impact of Bush encroachment:
Plant being controlled: Common Name:
Upright Tarbur Cape Pigweed Tassel Three – Awn Sweet Signal Grass Spider web Chloris Yellow Nutsedge Red Nutsedge Common Quick Grass Grabgrass African Goose Grass Common Thatching
Grass Sweet Buffalo Grass Kikuyu Grass Barr Bristle Grass Tall Khaki Weed Stalked Bristle Grass
Common Name: Brandy Bush Bastard Brandy Bush Black Wattle Silver Wattle Longleaf Wattle Golden Wattle Port Jackson Willow Red Eye Sand Olive Silky Hakea Guava Sesbania Camphor Bush SilverTerminalia Bluegums Lantana Cluster Pine American Bramble Bug Tree
Common Name: Candle Acacia Blue Thorn Buffalo Thorn Sweet Thorn Black Thorn Knob Thorn Scented Thorn Umbrella Thorn Three Thorn Bastard Umbrella
Thorn Camel Thorn False Camel Thorn Flaky Thorn “Fyndoring” Mopane Eupatorium Sickle Bush
Encroachment have an huge
impact on vegetation:
Impact of Bush encroachment:
Resolving Bush Encroachment: Chemical Treatment:
With chemical treatment of the invader species you can target the invaders selectively.
With enough knowledge and practice you can stay
away of non invasive plants. (Kamelthorn trees)
With the correct follow up time and procedures, the acceptable amount of bush encroachment can be
handled.
Chemical Treatment:
Only the invader species can be targeted.
Chemical Treatment:
Grass production much better after invader species have
been treated:
Chemical Treatment: Grass production
much better after invader species have been treated:
Before spraying August 2013
Same field , May 2014
Neighbouring camp 2 years after application:
Chemical Treatment:
Raise in grass production: From 120kg per hectare left, to
852kg per hectare right
Chemical Treatment:
Chemical treatment 18 years ago:
Followed up with numerous treatments, 4 years, 6 years
and 8 years:
Same treatment 18 years ago without any follow-up
treatments.
Chemical Treatment:
Small Sickle Bush showing signs of dying after 5mm rain.
Chemicals being sprayed with precision
5 Years after areal application
2 Years after hand application
Follow up treatment
Chemicals mixed:
Chemical Treatment:
After spraying an detailed listing of all the camps would be given to the client..
Chemical Treatment:
After spraying an detailed G.P.S map
would also be provided to the client:
Advantages of chemical treatment:
Treatment of individual plants is relatively fast
Application can be done selectively
It is labour intensive that creates job opportunities
The residue effect can oppress seedlings for some time.
The active ingredient can still be active for up to 3 years without any rain
Dead plant material can be harvested for wood, where the income be applied for further encroachment control
Follow up treatments is relatively cheaper than the first treatment, since most of the
invader species already have been targeted, only then would the regerminated plants be targeted.
Hand applied chemicals:
Disadvantages of chemical treatment:
Even with selective treatment of invader species, there is a possibility of damaging plants that have not been targeted, due to the presence of
their roots in an area, thus experience and correct application methods should be maintained.
The active ingredient can be slow working as it is depended on rain to
start working
The rate of application depends on the density of the invader plants
An field fire can break down the active ingredient, up to 50%, if rain have not been present after an application
Hand Applied chemicals:
After care procedures:
Most plants die in the first year of application, and the recovery of grass is relatively good
Follow-up treatment should be carried out 4 to 5 years after treatment, and then an further 8 years after that, it creates an ideal time frame
for dormant seeds to germinate.
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