3.6 human impact on the environment Flashcards
1
Q
what are some examples of human activity that have resulted in widespread habitat destruction, resulting in a biodiversity crisis as species compete for resources?
A
- deforestation
- agriculture
- overfishing
- pollution
- forestry
- mining
- urban expansion
2
Q
what can species extinction be caused by?
A
- changes in climate which reduce vegetation and decrease atmospheric oxygen levels
- human activity e.g the dodo bird
3
Q
what is an endangered species?
A
- one that is at risk of extinction in either all or a significant part of its range (where it is found)
4
Q
species are classified according to their vulnerability to extinction. what are the names of these categories?
A
- critically endangered
- endangered
- vulnerable
5
Q
what are some examples of threatened species today?
A
- mountain gorillas
- giant pandas
- polar bears
6
Q
what are some reasons why species are at risk?
A
- natural selectrion
- habitat destruction
- pollution
- overhunting and collecting
- overfishing and agriculture exploitation
- competition from introduced species
7
Q
how does natural selection mean species are at risk?
A
- requires mutations in the gene pool to confer a selective advantage
- where species cannot adapt to changes in their habitats fast enough due to insufficient mutations they can become threatened or extinct
8
Q
what is an example of habitat destruction meaning species are at risk?
A
- deforestation and hedgerow removal
- hedgerows contain many different plant species supporting a wide variety of animal life, but their removal to allow for larger fields to accommodate agricultural machinery and the subsequent loss of wildlife corridors has reduced species numbers and affected food chains
9
Q
what are examples of pollution that mean species are at risk?
A
- PCBs (polychlorinated biphenyls) were manufactured as coolants and have since been banned due to their toxicity and carcinogenic nature. they are still found in the environment close to manufacturing sites
- oil is shipped worldwide to meet our energy needs, but accidents at sea have led to the discharge of millions of gallons of crude oil
10
Q
what are examples of overhunting and collecting, causing species to be at risk?
A
- for food (meat)
- as exotic pets
- fashion
- traditional medicine (tiger bone and rhino horn)
- souvenirs and ornaments (turtle shell, ivory)
11
Q
what does conservation involve?
A
- the management of habitat to enhance biodiversity
- the protection, preservation management and restoration of natural habitats and their ecological communities to enhance biodiversity
12
Q
why is conservation important?
A
- ethical reasons : we have a responsibility to preserve the environment, not damage it
- possible medical uses : many drugs have been extracted from plants e.g quinine from Cinchona bark used to treat malaria, some chemotherapy drugs have a plant origin + more
- maintaining a healthy gene pool helps future-proof populations against environmental changes
- agriculture has selectively bred crops from wild varieties. in future, we may need to look at wild varieties to select suitable alleles to grow crops in harsher environments
13
Q
what are some conservation methods?
A
- legislation:
• CITES (the convention on international trade in endangered species) but difficult to enforce bc not all countries have signed up, and its v. difficult for police to catch the smugglers involved
• the EU Habitats Directive prevents collection of some birds’ eggs, and reduces the picking of wild flowers and overfishing
• established protected areas SSSIs (sites of special scientific interest), and nature reserves - captive breeding programmes in zoos and botanical gardens gardens involve:
• seed banks hold seeds from rare and traditional varieties in controlled environments, to protect against extinction of species
• sperm banks store sperm from threatened species and are used in captive breeding to ensure genetic variety within populations
• rare breed societies maintain older less commercial varieties
• species reintroduction has been used successfully following captive breeding programmes to reintroduce species back into the wild
• education through WWF (world-wide fund for nature) and the Countryside Commission, which are responsible for raising awareness + establishing nature reserves
• ecotourism e.g safaris, provide education and raises money to fund local conservation efforts
14
Q
ecotourism definition
A
- responsible travel to natural area that conserves the environment and improves the well-being of local people
15
Q
monoculture definition
A
the cultivation of a single species of crop
16
Q
what does agricultural exploitation refer to?
A
- the way in which food production has had to increase in efficiency and intensity to maximise crop yields in order to feed a growing population
17
Q
what is an issue in agricultural exploitation?
A
- causes conflict between conservation and the need to mass produce food
18
Q
what are examples of how issues in agriculture exploitation have led to problems?
A
- following WW2, larger field were created by removing hedgerows to allow for larger machinery, which led to the loss of habitat for many organisms and reduced biodiversity
- farmers employed monoculture by growing a single species of crops to further increase yields, as all plants require the same nutrients, and harvesting was easier
19
Q
what are some disadvantages of monoculture?
A
- it reduces biodiversity as there is only one habitat
- provides an ideal environment for pests, so pesticides and herbicides have to be used
- farming reduces the flow of recycling of nutrients as when plants die and decompose their constituent elements are returned to the soil, but farmers often remove crop residue and ∴ minerals from the soil. farmers have to add inorganic fertilisers to their fields to increase nutrient content. this can cause eutrophication
