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b6 (human impacts (when earth's population was much smaller, impacts…
b6
human impacts
when earth's population was much smaller, impacts of human activity were usually small and local, now, actions can have more widespread effects
increasing population puts pressure on environment, take land and resources to survive
people demanding higher standard of living, eg cars, smartphones, so we use more raw materials eg oil to plastics, and use more energy for manufacturing process, taking more resources from the environment more quickly
raw materials are being used up quicker than they're being replaced, one day will run out
producing and consuming creates waste eg waste chemicals, if not handled properly causes harmful pollution like sewage and toxic gases
negative impact on local biodiversity (number of species in the local area) and global biodiversity (number of species on the planet)
organism habitats
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abundance can be estimated by counting the number of individuals or percentage cover in samples, then scaling up
distribution can be studied by measuring how common an organism is in 2 sample areas, and comparing
or studying how distribution changed across and area eg by placing quadrats along a transect
quadrat
place 1m2 quadrat on the ground at random point, eg divide the area into a grid and use random number generator for coordinates
if it's at one spot and everywhere else is different, results won't be valid, count all important organisms
repeat many times, work out mean number of orgainims within the first sample area, number of organisms/number of quadrats
repeat in second sample area, compare two means
transects
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sample along the length using a quadrat, called a belt transect
mark out a line in the area, place quadrat at start and count and record organisms, take sample by moving quadrat down the line
difficult to count all individual organisms eg if grass, can calculate percentage cover by estimating percentage area of the quadrat covered by counting small squares
impact of waste on land
pollution that results from waste produced by humans kills plants and animals, reduicing biodiversity
toxic chemicals used for farming (pesticides and herbicides), bury nuclear waste underground, dump household waste in landfill sites
sewage and toxic chemicals from industry can pollute lakes, rivers and oceans, affects plants and animals that rely on them, chemicals used on land can be washed into water
smoke and gases released into the atmosphere can pollute the air, eg sulfur dioxide can cause acid rain
pooters
jars with rubber bungs sealing the top, and two tubes stuck through the bung
suck on the shorter tube, put end of the longer tube over an insect, sucked into jar
spend the same amount of time sampling two areas of similar size and compare the number of insects collected
pitfall traps
steep sided containers that are sunk in a hole in the ground, top partly open
leave the trap overnight in first sample area, insects fall into the container, can't get out, can be counted
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sweep net
net lined with strong cloth for insects, spiders from long grass
stand still in first area and sweep once left to right, quickly sweep up and turn the insects into a container to count
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pond net
used for collecting insects, water snails from ponds and rivers
stand in sample area, sweep along the bottom of pond or river, turn into white tray with water to count, repeat in second area and compare
population size
work out mean number of organisms be meter squared, then multiply the mean by the total area of the habitat
population size = number in first sample x number in second sample/number in second sample previously marked
abiotic factors
temperature, moisture level, light intensity, soil pH
thermometer for temp, light sensor for light intensity, soil moisture meter for level of moisture in soil, measure soil pH using indicator liquid
land use
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four main human activities : building, farming, dumping waste and quarrying for metal ores
habitat destruction
woodland clearance : done to increase area of farmland and can result in reduction in number of tree species, reduces biodiversity, destroys habitats, species will die or be forced to migrate elsewhere, reduces biodiversity
monoculture : areas of land used to grow a single crop, eg palm oil plantations, efficient way to grow but can lead to reduction in biodiversity, habitats are cleared to make way for large fields
biotic factors
availability of food, number of predators