3.6 Human Impact on the Environment 3 Flashcards
Endangered species
A species that due to a loss of habitat or rapid decrease in population numbers is at risk of extinction
When is a species described as extinct
When all the 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 (e.g. deforestation, removal of hedegrows)
Pollution (e.g. oil, PCBs)
Overhunting by humans
Introduction of new competitors (e.g. domesticated animals)
Non-contiguous populations
What is conservation?
The maintenance of ecosystems and biodiversity by humans in order to preserve the Earth’s resources
Describe how conservation can be achieved
Protection of habitats - e.g. nature reserves, national parks, SSSIs(is)
Protection of endangered species e.g. making hunting illegal, breeding programmes increase population size
International cooperation e.gg restricting trade of endangered species and their parts
Species reintriduction
Gene and sperm banks
Seed banks
Why is the conservation of genes pools important?
Many plant species are yet to be discovered and may contain chemicals that could be used in future medicines.
Protection of potential future food sources.
Some alleles may provide selective 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 e.g. coppicing, selective cutting, long rotation time
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 bigger net mesh sizes
using lines rather than nets
fishing quotas and exclusion zones
avoiding overfished species, fishing non-traditional species
limiting fishing fleet sizes
marine stewardship council certification
fish farming
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, larger, outcompete wild populations
Bioaccumulation of pesticides
Farmed fish contain high concentrations of toxic chemicals (e.g. dioxins, PCBs)
Sustainability??
Using resources in a way that also maintains them for future generations
