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In fynbos-areas the water balance of mountain catchment areas have been upset by dense patches of alien plants, thus creating a far bigger fire hazard than the natural vegetation.
All seven of the most important biospheres are threatened by alien plants, with fynbos, savannah and wooded areas being affected most severely. Up to now efforts to kerb alien plants in the formal conservation areas of the sub-continent have met with varied success, when directed at alien trees and shrubs. Invasion by weeds and grasses are mostly ignored and little ecological information is available on this problem.
The eradication of alien species is a costly and time-consuming process.
1. Write short notes on one alien plant and one alien animal found in your area.
a) Alien plant
b) Alien animal
Some alien plants
Jointed cactus
Invasion by the jointed cactus hinder farming activities and cause the value of the land to depreciate. It diminishes the grazing potential of the veld.
Animals can become covered with sores and ulcerations as a result of the barbed thorns hooking into their flesh.
Oleander
Parts of the plant are poisonous for humans, birds and other animals.
Early signs of poisoning include sweating, loss of appetite, nausea, vomiting, dizziness, stomach cramps, etc. Serious cases can lead to death due to heart failure or paralysis of the respiratory system.
Port Jackson
The Port Jackson was originally planted to bind the sand on the Cape Flats.
The bark of the trees was initially used for the tanning of leather, but was later replaced by better types of bark.
The wood of the Port Jackson is softer en weaker than that of Rooikrans, which is a better sand-binder.
Lantana
This alien plant is so aggressive in the warmer regions of the Cape that it can choke trees of 10 metres in height.
Invasion in plantations hamper forestry activities. Animals eating the leaves may die.
Poisoning in humans may cause kidney failure, leading to death within three weeks.
Rooikrans
Rooikrans forms thick, impenetrable stretches of large shrubs or low trees with entangled crowns.
They cause a serious problem, as the germination suppresses the growth of indigenous plants, causing them to disappear.
Learning Outcomes (LOs)
LO 1
Geographical Enquiry
The learner will be able to use enquiry skills to investigate geographical and environmental concepts and processes.
Assessment Standards(ASs)
We know this when the learner:
1.1 identifies and selects a variety of geographical and environmental sources relevant to an
enquiry [uses fieldwork and other enquiry methods; finds sources];
1.2 interprets maps and atlas information, graphical and statistical sources [works with sources].
LO 3
Exploring Issues (social and environmental)
The learner will be able to make informed decisions about social and environmental issues and problems.
We know this when the learner:
3.3 investigates possible ways of reducing resource consumption [makes choices].
ACTIVITY 1
ENCOURAGED : Diversified (mixed) farming should be encouraged in areas with sufficient rainfall. This will prevent that farmers rely solely on one type of farming, and suffer financial losses when prices go down. It also helps to combat the exhaustion of the soil.
2. If these substances are used correctly (scientifically), it can help to increase production, which is to the advantage of the farmer and his land. Irresponsible and uncontrolled application of the said substances can result in the destruction of ecosystems and the poisoning of water resources, so that the land may become completely unproductive.
3. Urbanisation results in a rapid growth of the population in urban areas. This in turn causes a large demand for housing areas and commercial sites, the result of which is deforestation, or even the impingement on precious agricultural land, as urban areas expand towards the outskirts of towns and cities.
ACTIVITY 2
Rayon material: Natural fibres
Wooden planks: Hardened synthetic material – will be difficult
Wooden sawdust: Cottonwool and synthetic fibre or wool fibre
Paper: Impossible – recycling necessary
Sleepers: Concrete
Wooden boxes: Cardboard that can be recycled
Pencils: Plastic-covered graphite
Wetlands form a unique ecosystem and has to be protected.
Wetlands act as a “sponge” to absorb surplus water.
To maintain biodiversity.
Accommodates a large variety of plant and animal species.
Interest of the community.
2. Trees and woods play an essential role in the regulation of atmospheric and climatic processes.
It stores carbon and keeps local water cycles intact.
Stabilises soil (compact) against erosion.
Reduces the impact of floods.
Maintains species – ecosystem.
Tourism and recreation.
ACTIVITY 3
Answer will depend on area where you live.
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