Agricultural exploitation Flashcards
How has farming practises degraded agricultural land
1) hedgerow removal
2) monocultures
3) overgrazing
What is a monoculture and why is it bad
the growth of large numbers of genetically identical crop plants in a defined area
- yield progressively declines
- roots are the same length so same minerals are absorbed causing decreased nutrients at certain soil depths
- genetically identical so susceptible to same pests so increased pesticides are used
How does over-grazing degrade land
causes grassland to become unsustainable
hooves compact soil, decreasing aeration preventing infiltration of water into soil so roots can penetrate
What are the reasons for deforestation
- building material
- fuel
- packaging
- farming needs clear land
- roads
- infrastructure
what are the consequences of deforestation
1) soil erosion
2) lowland flooding
3) land becomes wetter
4) reduced seed germination
5) habitat loss
6) increase CO2
why does the land become wetter after deforestation
evaporation is slower than transpiration so water returned to the atmosphere at a slower rate
water fills the soils airspace so oxygen available to roots decreases
why is it hard for seeds to germinate after deforestation
it takes longer for wetter soils to warm up so soil is cold
this reduces germination and root activity
List some forest management techniques
1) slash and burn
2) coppicing
3) selective cutting
describe slash and burn
a small area of forest is cut and burned
the soil increases in fertility due to the ashes of the burnt trees
people grow crops on this soil
after fertility decreases people allow the area to regenerate
Describe coppicing
1) a tree trunk is cut leaving a stool
2) new shoots emerge from the stool over time which grows into poles and thicken
3) poles can be cut on rotation to produce timber of different widths
4) long rotation times increase sustainability allowing a variety of habitats to develop increasing biodiversity
Describe selective cutting
felling only some trees and leaving others in place
good for steep slopes allowing roots to help bind soil and decrease erosion
How can land be used efficiently with good forestry practise
1) planting trees optimum distance apart- reduces intra-specific competition increasing quality of timber
2) control of pests and disease- fewer trees would need to be felled as timber is of better quality reducing total land needed
3) cutting a similar number of trees each year- allows the ecosystem to be maintained and habitats left intact
Define overfishing
The rate at which fih are harvested exceeds the rate at wich they reproduce
what is the difference between drift netting and trawling
1) nets suspended near the surface of the water to catch pelagic fish which swim into the net
2) a large net dragged across sea floor to catch deep living fish
what are the effects of overfishing
1) food chain impacts- bycatch of prey species not eaten by humans causes food declines for predator species to cause decreased populations
2) reduction of fish populations damages livelihoods of fishermen
