10- human effects on ecosystem Flashcards
(13 cards)
human influences on ecosystems
• Ecosystem diversity is reduced by deforestation, mining and building.
• Species diversity is reduced by farming, fishing, hunting, habitat destruction, and alien species.
• Genetic diversity is reduced by selective breeding, and competition with humans.
climate change evidence
Records of CO2 level:
• Increasing levels of CO2 contribute towards climate change, as CO2 is a greenhouse gas and is involved in the greenhouse effect.
Tree rings:
• They tell us about the climate while the tree is growing.
• Narrow annual rings mean growth was slow so temperature was colder.
• Wider annual rings mean growth was faster so temperature was
warmer.
causes of climate change
• Burning fossil fuels, which releases CO2 removed by plants.
• Deforestation, which reduces photosynthesis and releases CO2 by combustion.
• Agriculture, as methanogenic bacteria in cows produce methane.
• Landfills, as methanogenic bacteria are found in landfill sites.
impacts of climate change on abiotic changes
• Ice is melting - the arctic ice sheet is shrinking by 10% per decade.
• Glaciers are retreating - this can cause temporary flooding.
• Sea levels are rising due to melting and thermal expansion of water.
• Ocean currents are changing due meltwater and decreased salinity.
• Weather patterns are changing.
impacts of climate change on biotic changes
• Species move to cooler areas - this can lead to extinction of some species due to competition.
• Seasonal cycles start earlier.
• Farming is affected.
• Disease spreads as microorganisms now survive in areas they couldn’t before, as it is warmer.
depletion of biological resources- overfishing
• Large factory ships → trawl deeper water with larger nets, and use sonar to find shoals.
Fish are removed faster than they can breed, so fish stocks decline.
• Fine-meshed nets → catch many species that cannot be sold (bycatch), and young fish.
Bycatch is dumped into the sea, forming detritus. Young fish cannot breed to replace the fish stocks the next season.
• Bottom trawling → physically disturbs organisms and habitats, and destroys food webs. This results in very small population sizes, and increases the chances of inbreeding.
treaties
There are many international agreements to support conservation, encourage the sustainable use of resources, and protect endangered species.
CITES
• Convention on international trade in endangered species of wild fauna / flora.
• It regulates trade of living organisms and their products by classifying them into 3 appendices depending on the level of threat to the organism.
• CITES has had some success at conserving biodiversity (e.g. stopping ivory trade; bringing shark and turtle species back from the brink of extinction).
limitations of CITES
• It deals exclusively with trade.
• Many countries haven’t signed up.
• There is no legal obligation to abide by the rules - only trade sanctions are used.
• Commercial interests often override scientific evidence.
preservation
Preservation serves to maintain the biodiversity and leave a habitat intact by minimising the effects of human activities on the particular habitat.
reducing possible causes of climate change
• Growing plants to use as biofuel, which are carbon neutral - CO2 is released when fuel is burnt, but it is also removed from the atmosphere by the plants it is made from.
• Reforestation to increase the rate at which CO2 is produced.
conservation
Conservation serves to maintain or increase the biodiversity within a particular habitat through the sustainable use of natural resources.
conserving fish stocks
• Enforcing quotas to limit the number of each species that can be caught each year.
• Limiting certain types of fishing (e.g. bottom trawling).
• Limiting the size of mesh in fishing nets, so small young fish are not caught.
• Limiting fishing seasons to avoid fish breeding seasons.
• Banning the fishing of specific species altogether.
• Setting up marine reserves (areas where there are no fishing, boats or diving).
• Using fish farms.
