A2C1 - Chapter 6 - Human impact on the environment Flashcards
(21 cards)
Describe what is meant by an endangered species.
A species that due to a loss of habitat or rapid decrease of population numbers is at risk of extinction.
When is a species describes as extinct?
When all members of the species are dead.
Outline the potential causes for the extinction of a species.
Natural selection due to selection pressures.
Loss of habitat (eg deforestation)
Pollution (eg oil or PCBs)
Overhunting by humans
Introduction of new competitors
Non-contiguous populations
What is conservation?
The maintenance of ecosystems and biodiversity through human action in order to preserve the Earth’s resources.
Describe how conservation can be achieved. (6)
- Protection of habitats. eg nature reserve
- Protection of endangered species. eg making hunting illegal
- International cooperation. eg restricting trade of endangered species and their parts.
- Species reintroduction
- Gene and sperm banks
- Seed banks
Why is the conservation of gene pools important?
Many plant species are yet to be discovered and may contain chemicals that could be used in future medicine.
Protection of potential future food sources.
Some alleles may provide selection advantages, preventing extinction.
Each species and its genes are precious.
What is agricultural exploitation?
The increase in efficiency and intensity of food production in order to meet growing demands.
What is deforestation?
The removal of trees from land which is subsequently used to grow crops or provide space for cattle.
Outline the consequences of deforestation.
Loss of biodiversity.
Climate change
Habitat loss
Soil erosion
Desertification
Lowland flooding
What do managed forests involve?
Sustainable replanting and regeneration. Eg:
Coppicing
Selective cutting
Long rotation time
What is overfishing?
The excessive fishing of an area at a rate which exceeds potential replenishment of the species.
Outline the methods employed to regulate fishing.
Using lines rather than nets.
Regulating net size
Fishing quotas and exclusion zones
Avoiding overfished species
Limiting fishing fleet sizes
Marine stewardship and council certification
Fish farming
What is fish farming?
The breeding of fish commercially in enclosures for food to combat overfishing.
Describe the problems of fish farming.
Rapid spread of disease.
Escape of farmed fish = spread disease to wild populations and could outcompete wild populations too.
Bioaccumulation of pesticides
Farmed fish contain high concentrations of toxic chemicals (eg: dioxins, PCBs)
Define sustainability?
Using resources in a way that also maintains them for future generations.
Environmental monitoring is required for conservation. Give some examples of factors that can be monitored.
Air quality
Water quality
Soil quality
What are planetary boundaries?
A set of nine limits proposed by a group of environmental and earth system sciences within which human activity can operate without risk of irreversible damage to the planet.
Which four planetary boundaries have been crossed?
Climate change
Biosphere integrity
Land system change
Biogeochemical flows
Which two planetary boundaries are avoidable?
Ocean acidification
Fresh water use
Whcih planetary boundary has been avoided?
Ozone depletion in the stratosphere
Which planetary boundaries are not quantified?
Atomospheric aerosols.
Introduction of novel entities.
