Agricultural Exploitation + Overfishing

Why does agricultural exploitation take place?

The efficiency and the intensity of food production has to continually increase in order to meet the demand for food

What is a monoculture?

The agricultural practice of growing of a single crop, breed or variety over a large area

Why are monocultures damaging?

It fails to provide different microhabitats like mixed crops would, so these areas lack biodiversity

Give 2 reasons as to why growing the same crop on the same plot year on year is damaging

1. The roots are always the same length so they extract the same minerals from the same depth of soil (Increased use of inorganic fertiliser)
2. The same crop is always susceptible to the same pests (Increased use of insecticides, herbicides and fungicides)

What effect does overgrazing by cattle have?

It causes the grassland to become unsustainable, hooves compact the soil preventing water draining through. Roots cannot penetrate the soil so grass cannot grow

Give 3 reasons why deforestation happens

* Timber is widely used for building and fuel
* The land is cleared for farming
* New roads are built through the forest to provide transport infrastructure for these activities

What is soil erosion (happens due to deforestation)?

The removal of topsoil, which contains valuable nutrients. Deforestation on higher slopes leads to a loss of topsoil on these slops, meaning growth is unlikely to happen

What matter is described as being a sponge for heavy rainfall?

Plants, humus and leaf litter

If there is a lack of this matter what happens?

* Evaporation returns water more slowly to the atmosphere than transpiration, water fills the soil’s airspaces decreasing oxygen for the roots
* It takes longer of wet soil to heat up causing germination and root activity to be reduced
* Cold and damp soil favours the growth of denitrifying bacteria, decreasing nitrates and in turn fertility

Due to slower evaporation what happens to rainfall?

There’s less rainfall which speeds up the process of desertification

How many plants and animals go extinct a day due to rainforest deforestation? Why could this be damaging in medical development?

Around 25 a day, its possible that some plants may have valuable clinical properties but they’d never be discovered

What effect does deforestation have on the atmosphere?

Photosynthesis is decreased meaning that less CO2 is absorbed, meanwhile the process of deforestation increases CO2 levels

What is the process of ‘slash and burn’?

A small forest area is cut and burned, that ash is used as a fertiliser for crop. Once the soil is no longer fertile the area is left to regenerate

What is coppicing?

The cutting down of trees close to the ground and leaving them for several years to re-grow to be cut down the same way

What is selective cutting?

Felling only some tress and leaving others in place, to help maintain nutrients in to soil and minimise the amount of soil that’s washed into nearby waterways

Give 3 examples of good forestry practice

* Planting trees the optimum distance apart
* Controlling pests and diseases
* Cutting a similar number of trees each year allowing the forest ecosystem to be maintained

What types of trees are being grown?

Native trees are wanted as it allows native forests to regenerate and preserves biodiversity

What is overfishing?

The rate at which fish are harvested exceeds the rate at which they reproduce

What 2 damaging fishing practices are used?

Drift netting and Trawling

What are the effects of overfishing?

* The species being hunted decreases to possible levels of extinction
* Prey species can also be caught leading to a limited food supply for many species
* It damages the livelihood of fishermen

Name 5 different methods of regulating fishing

1. Mesh size increased so that young fish aren’t caught
2. Quotas set limiting the number of fish brought to land
3. Legislation controlling the number of days spent at sea
4. Exclusion zones to prohibit fishing in certain areas at certain times of year
5. Fish farming

What is fish farming?

Fish are bred and grown to maturity in ponds where predation is reduced and food supply is maintained

What are the advantages of raising fish rather than other meat?

* A greater proportion of fishes’ bodies are edible
* Fish convert their food into protein more efficiently
* Fish farming has a lower carbon footprint

Give 3 main disadvantages of fish farming

* The fish are very densely stocked so they easily transmit disease, farmers use more pesticides
* The farms create a lot of pollution, eutrophication can take place for example
* Escaped fish are a problem as they grow rapidly and can out-compete wild species, and can transmit diseases and parasities