A Level Biology - Human Impact

A Level Biology - Human Impact
Covers:
Important definitions,
Conservation,
Agriculture,
Overfishing,
Fish farming,
Planetary boundaries

Transcript

1. Human impact
2. Important definitions • Agricultural exploitation – the increase in efficiency ad intensity of food production • Biodiversity – number of species and the number of individuals in each species in a given area • Biofuel – fuel made by biological processes (anaerobic respiration) instead of geological processes (long term heat and combustion of fossil fuels) • Conservation – protection, preservation, management and restoration of natural habitats and their ecological communities, aims to maintain species and genetic biodiversity while allowing human activity to continue • Coppicing – cutting down trees close to the ground and leaving them to re-grow over several years • Core boundary – crossing these boundaries would drive the Earth into a new and unpredictable state with severe consequences for the biosphere • Deforestation – the complete loss of trees in a specific area due o human activity • Ecotourism – responsible travel to natural areas that conserve the environment and improves the well being of local people
3. Important definitions - continued • Freshwater – water with a low concentration of dissolved salts, AKA sweet water to contrast with more salty seawater • Long rotation time – many years left between harvesting adjacent areas of forest, variety of habitats develop, favouring diverse wildlife • Monoculture – the growth of large numbers of genetically identical crop plants in an area • Overfishing – rate at which fish are being harvested exceeds the rate of which they are reproducing • Planetary boundary – a threshold value for a global process that is affected by human activity, crossing these will could generate abrupt and irreversible environmental changes • Selective cutting – felling only some trees, leaving others
4. Why species are becoming extinct • Natural selection – survival of the fittest, evolution and mutation • Non-contiguous (non touching) – individuals cannot touch/interbreed so there is insufficient genetic diversity • Loss of habitat – deforestation, natural disasters, draining wetlands, different farming techniques and loss of hedgerows • Overhunting by humans – poachers, trophy hunting and killing for medicine • Competition from introduced species – more competition for resources • Pollution – plastic in the sea and oil leaks/spills
5. Conservation • Protecting habitats (national parks, SAC’s, SSSI’s and nature reserves) • International cooperation restricting trade (ivory and whaling) • Zoos and breeding programs • Sperm banks store genes of economically important animals and threatened species, sperm samples can be sent around the world instead of animals • Seed banks maintain stocks of seeds of traditional varieties and of valuable species in highly controlled conditions • Rare breed societies maintain older, less commercial varieties for special characteristics (hardiness and wool production) • Species reintroduction • Education • Legislations preventing overfishing, overgrazing, hunting of game, collection of bird eggs, picking wild flowers and plant collecting • Ecotourism
6. Conservation - continued • Maintains species and genetic biodiversity • Essential for protecting potential sources of new crops for agriculture and new pharmaceuticals for medicine • Diversity of alleles is essential in combating climate change • Some alleles provide selective advantages to individuals, preventing extinction • Ethical issue • Each species and their genes is/are unique and precious
7. Agriculture exploitation • Intensive farming has led to increase in chemical fertilisers, herbicides and pesticides • Mechanisation requires larger fields • Reduction in hedgerows which are an important habitat and losses reduce biodiversity • Large field are used to grow monocrops, one single cop grown on a massive scale
8. Deforestation and overgrazing • Soil erosion • Lowland flooding • Desertification • Habitat loss decrease in biodiversity • Climate change • Soil compaction reduces air spaces and inhibits nitrogen fixing and nitrifying bacteria • Loss of soil fertility • Water is unable to penetrate and grass growth is inhibited Management techniques > Coppicing Selective cutting Crop rotation
9. Overfishing management • Regulating mesh size • Quotas and landing size regulations (leads to fines) • Exclusion zones • Marine stewardship council certification • Legislation limiting size of fishing fleets or controlling amount of days spent at sea • Fishing alternative and non traditional species • Using lines and not nets
10. Fish farming problems • Densely stocked fish – more ease for disease to spread so huge amounts of antibiotics are needed to keep the fish relatively healthy • Pesticides used to control fish parasites can also harm marine invertebrates • Interbreeding with wild fish can occur if farmed fish escape which ca potentially weaken wild stocks • Pollution • Eutrophication when fish excretion, waste food and fertiliser are carried into surrounding water • Wild and farmed salmon can contain high levels of dioxins and polychlorinated biphenyls (highly toxic environmental persistent organic pollutants)
11. Planetary boundaries
12. 1. Climate change boundary – core boundary that has been crossed, release of CO2 on a massive scale has lead to an enhanced global warming effect 2. Biosphere integrity boundary (biodiversity loss and species extinction boundary) – core boundary that has been crossed, balance between protection/conservation of habitats and human needs (agriculture exploitation) 3. Land use boundary – misuse of land resulting in too little food being produced, balance between protection/conservation of habitats and human needs (agriculture exploitation) 4. Biogeochemical flows boundary – cycling of minerals through the abiotic and biotic components of an ecosystem, disruption to nitrogen cycle 5. Stratospheric ozone boundary – the only boundary to be avoided, UV light cause CFC’s to release chlorine as free radicals which break down the ozone layer, aerosols and refrigerators with CFC’s has been reduced and as a result had reversed the depletion of the ozone layer 6. Ocean acidification boundary – pH of oceans has decreased as CO2 in the atmosphere has increased, oceans are increasing in acidity and as carbon carbonate leaches from shells, exoskeletons of molluscs become softer increasing their vulnerability 7. Freshwater use boundary – includes ice sheets, ice caps, glaciers, icebergs, ponds, lakes, rivers, streams and groundwater, climate change and pollution will deplete sources 8. Atmospheric aerosol loading boundary – not possible to suggest boundaries 9. Novel entities boundary – not possible to suggest boundaries