human impact Flashcards
(17 cards)
define extinction
the total loss of a species
define endangered
species at risk of becoming extinct because
there are few breeding pairs left
what are some conservation methods?
- Nature reserves and SSSIs are protected by law.
- Trade in endangered species and products derived from them are restricted or banned
- Captive breeding programmes in zoos and botanic gardens
- Sperm and seed banks preserve gene pools for the future
- Reintroduction programmes enhance
the numbers of endangered species
define agricultural exploitation
the need to increase efficiency and intensity of food production to meet increasing demands by
a rapidly increasing human population
what are the reasons for extinction?
- Natural selection.
- Habitat destruction
- Pollution
- Hunting and collecting
- Competition from domestic animals
define conservation
the planned management of ecosystems to enhance biodiversity and protect gene pools
what does algricultural exploitation involve?
- Removal of hedgerows – destroying habitats
- Monocultures – reducing available niches.
- The use of insecticides, herbicides and fertilisers
- Ecosystem destruction to provide additional agricultural land
Why is conserving gene pools important?
- Plants may provide new medicines for the future
- Many wild crop plants may have useful genes
that could be bred back into crops to increase productivity - It is unethical to drive species to extinction and reduce biodiversity
- Reduced gene pools make species more vulnerable to extinction
as there is less variation
define deforestation
the mass removal of trees to use as timber or fuel or to repurpose the land use for agriculture or building
define overfishing
where fish are caught at a higher rate than they
reproduce and grow
define fish farming
where fish are intensively reared in ponds/tanks
or nets
what are the consequences of deforestation?
- Soil erosion – soil is no longer protected from rain by the canopy, as roots decompose, they no longer hold the soil together so it is eroded by wind and rain
- Flooding - evaporation from soil removes less water than transpiration, waterlogging encourages denitrification and soil
loses nitrates. - Habitat loss reduces biodiversity.
- Less photosynthesis means that less CO2
is removed leading to
global warming and climate change
what are the solutions to deforestation?
- Selective felling
- Replanting the correct mix of species and allowing them to regenerate
- Protecting areas
what are the consequences of overfishing?
- Fish populations may be reduced in size to the extent that they lose genetic diversity.
- Size of fish caught is reduced as they don’t have time to grow.
- Fish population has fewer individuals and cannot replace harvested fish
what are the solutions to overfishing?
- Quotas
- Restricted fishing seasons.
- Exclusion zones
- Increased mesh sizes
- Limiting the size of fishing fleets
what are the benefits of fish farming?
- Less fish need to be harvested from the wild, allowing fish stocks to replenish.
- Fish have been selected for high growth rates and therefore large size and increased yield
what are the consequences of fish farming?
- Excess fish food, egesta and excreta fall out of the nets and can cause eutrophication
- Parasites and diseases spread quickly through the
overcrowded fish. - Prophylactic antibiotic use may lead to antibiotic resistance
- If farmed fish escape they could outcompete wild fish or interbreed with them,
pushing wild fish to extinction - The feed is often made from harvested wild fish
