Human interaction with ecosystems Flashcards
Draw and label the structure of a mollisol
List the features of the A horizon
Crumb structure
Mull humus; black and nutrient rich
many earthworms live here and cause rapid organic decomposition
List the features of the B horizon
There is no B horizon, as the low rainfall means there is little leaching which creates the B horizon
List the features of the C horizon
In the summer capillary action causes CaCO3 nodules to be deposited
Lies on lime parent rock
List the features of mid latitude grasslands
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
Describe how temperature, rainfall and plant growth vary from each season in the grasslands
What is monoculture?
Monoculture is an agricultural system where the land is used to grow thje same crop year after year.
Why do farmers use monoculture?
What are the effects of monoculture?
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
What was the big event in the grasslands during the 1920s
The Dust Bowl Problem
What are shelter belts?
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
What is crop rotation?
Crops rotate fields each year to allow soil to replenish
This provides a recovery period and improves soil structure
What is contour ploughing?
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
What is mulching?
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
What are cover crops?
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
What is irrigation?
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
What are biotic components?
Living organisms
What are abiotic components?
Non-living factors
What is trophic structure?
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.
Draw and label the nutrient cycle
