Human interaction with ecosystems

Question 1

Draw and label the structure of a mollisol

Answer 1

Question 2

List the features of the A horizon

Answer 2

Crumb structure

Mull humus; black and nutrient rich

many earthworms live here and cause rapid organic decomposition

Question 3

List the features of the B horizon

Answer 3

There is no B horizon, as the low rainfall means there is little leaching which creates the B horizon

Question 4

List the features of the C horizon

Answer 4

In the summer capillary action causes CaCO3 nodules to be deposited

Lies on lime parent rock

Question 5

List the features of mid latitude grasslands

Answer 5

Climax vegetation reaches 2.5 metres in height

Grass roots extend 2 metres depth into the soil to reach the water table

Grazing and lack of rainfall mean trees do not grow

Annual average temps are high

Annual rainfall is around 500mm

There is a threat of drought

Rainfaill is lowest in the rainshadow of the rockies

Question 6

Describe how temperature, rainfall and plant growth vary from each season in the grasslands

Answer 6

Question 7

What is monoculture?

Answer 7

Monoculture is an agricultural system where the land is used to grow thje same crop year after year.

Question 8

Why do farmers use monoculture?

Question 9

What are the effects of monoculture?

Answer 9

After harvest soil is left bare, and is eroded by wind

Repeated ploughing breaks up the root system and ruins the humus layer

The cereals have few roots, so the soil is not as bound together

Removal of organic matter leads to leaching of nutrients in soil

Question 10

What was the big event in the grasslands during the 1920s

Answer 10

The Dust Bowl Problem

Question 11

What are shelter belts?

Answer 11

Lines of trees planted to act as wind breaks

It reduces erosion, provides habitats, but is slow at growing

The Canadian Permanent Cover Programme encourages this by $40/acre/year for 10 years, or $70/acre/year for 21 years

Question 12

What is crop rotation?

Answer 12

Crops rotate fields each year to allow soil to replenish

This provides a recovery period and improves soil structure

Question 13

What is contour ploughing?

Answer 13

Ploughing follows contour lines, preventing excessive erosion

Water is given time to soak in, and erosion is averted

The Soil Erosion Service pays farmers to do so e.g. Nebraska

Question 14

What is mulching?

Answer 14

Any material left on the field, like plant stubble, is covered in soil.

This protects the soil surface and increases infiltration and reduces soil loss

Minimum residue cover 1500kg/hectare is required however

Question 15

What are cover crops?

Answer 15

Crops are planted to protect the soil when the main crops don’t cover the ground

This adds organic matter, and legume crops add nitrogen to the soil and decrease wind and water erosion

Question 16

What is irrigation?

Answer 16

Boom sprinklers water crops regularly to mitigate the effects of being reliant on rare rainfall.

This is expensive; boom sprinkler arms require as much water as Belfast City.

Allows monoculture to continue and means the ground must be replenished with artificial fertiliser

Question 17

What are biotic components?

Answer 17

Living organisms

Question 18

What are abiotic components?

Answer 18

Non-living factors

Question 19

What is trophic structure?

Answer 19

A producer produces energy (autotroph), and is eaten by a heterotroph. This is a tropic level. The heterotroph can be eaten by another heterotroph; this is also a trophic level.

Question 20

Draw and label the nutrient cycle

Answer 20