Humans and the environment

04.13.2020
08:54:14
Biology/ grade 10- Today’s topic- Negative impacts of intensive livestock production and habitat destruction course book- pages295 and 296
Main points-
The negative impact of livestock production:

Intensive livestock production is also known as ‘factory farming’.
Chickens and calves are often reared in large sheds instead of in open fields.
Their urine and faeces are washed out of the sheds with water forming ‘slurry’.
If this slurry gets into streams and rivers it supplies an excess of nitrates and phosphates for the microscopic algae.
This starts a chain of events, which can lead to eutrophication of the water system.
Overgrazing can result if too many animals are kept in a pasture.
They eat the grass down almost to the roots, and their hooves trample the surface soil into a hard layer.
As a result, the rainwater will not penetrate the soil so it runs off the surface, carrying the soil with it.
The soil becomes eroded.


The problems of world food supplies:

There is not always enough food available in a country to feed the people living there.
A severe food shortage can lead to famine.
Food may have to be brought in (imported).
The redistribution of food from first world countries to a poorer one can have a detrimental effect on that country’s local economy by reducing the value of food grown by local farmers.
Some food grown by countries with large debts may be exported as cash crops, even though the local people desperately need the food.


Problems which contribute to famine:

Climate change and natural disasters such as flooding or drought; waterlogged soil can become infertile due to the activities of denitrifying bacteria, which break down nitrates.
Shortage of water through its use for other purposes, the diversion of rivers, building dams to provide hydroelectricity.
Eating next year’s seeds through desperation for food.
Poor soil, lack or inorganic ions of fertiliser.
Desertification due to soil erosion as a result of deforestation.
Lack of money to buy seeds, fertilizers, pesticides or machinery.
War, which can make it too dangerous to farm, or which removes labour.
Urbanisation (building on farmland); the development of towns and cities makes less and less land available for farmland.
An increasing population.
Pest damage or disease.
Poor education of farmers and outmoded farming practices.
The destruction of forests, so there is nothing to hunt and no food to collect.
Use of farmland to grow cash crops, or plants for biofuel.

Removal of habitats
Farmland is not natural habitat but, at one times, hedgerow, hay meadows and stubble fields were important habitats for plants and animals.
Intensive agriculture has destroyed many of these habitats; hedges have been grubbed out to make fields larger, a monoculture of solage grasses has replaced the mixed population of a hay meadow and planting of winter wheat has denied animals access to stubble fields in autumn.
As a result, populations of butterflies, flowers and birds have cashed.
The development of towns and cities (urbanisation) makes a great demand on land, destroying natural habitats.
The crowding of growing populations into town leads to problems of waste disposal.
The sewage and domestic waste from a town of several thousand people can cause disease and pollution in the absence of effective means of disposal, damaging surrounding habitats.


Extraction of natural resources:

An increasing population and greater demands on modern technology means we need more raw materials for the manufacturing industry and greater energy supplies.
Fossil fuels such as coal can be mined, but this can permanently damage habitats, partly due to the process of extraction, but also due to dumping of the rock extracted in spoil heaps.
Oil spillages around oil wells are extremely toxic.
Once the oil seeps into the soil and water systems, habitats are destroyed.
Mining for raw materials such as gold, iron, aluminium and silicon leaves huge scars in the landscape and destroys large areas of natural habitat.

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