B2.1 human problems, sampling strategies Flashcards
For most of human history our global carrying capacity was around…
600 million people
what meant we were able to overcome limiting factors
our mental capacity
what stopped food being a limiting factor
Agriculture was invented in around 8500 BC in Syria. Basic herdsmanship and cultivation was improved by the invention of the plough in Egypt.
what key moment stopped disease being a limiting factor
Germ theory started scientists looking at causes and cures for disease particularly spurred by the
Bubonic Plague.
the industrial revolution helped humans…
overcome all limiting factors technocentrically
in the industrial revolution, what inventions stopped disease (2), food and space, predators
- Sewer systems to eradicate disease
- Transports systems to use all space and attain food
- Weapons systems to eradicate predators
- Medicine to cure even more disease.
what percentage of land surface remains unaffected by humans?
3%
what is the carrying capacity or niche for humans?
there isn’t one! we have no definable niche as we have been able to overcome every limiting factor. our cc estimate can only be ‘now’
what are the 3 approaches to sampling?
random sampling, transects, systematic sampling
what are random quadrats used to do
determine the species in an area
method for random quadrats
- place random quadrats in an area (generated mathematically to remove bias)
- estimate population using either % cover or % frequency
- multiply up
whats the minimum amount of intervals you can have in a transect
7
an alternative to transects could be…
splitting an area into arbitrary zones, eg: low tide, high tide, foredunes, white dunes, grey dunes etc. and then take a quadrat from each of these areas.
what is an example of opportunistic sampling
looking at organisms in a rock pool
how to do percentage cover
place quadrats in an area and make broad estimates about the percentage cover of each plant in each square. so for example, 20% dandy lions, 70% grass and 10% daisies.
disadvantage of percentage cover
it is affected by the size of the plant/leaves and so larger species will be over represented.
how to calculate percentage frequency
- note how many squares in the quadrat each species appeared in
- divide it by the total number of squares.
- Average this out across your quadrats and multiply up.
what is the ACFOR scale?
Abundant (30%+)
Common (20 to 20%)
Frequent (10 to 19%)
Occasional (5 to 9%)
Rare (1 to 4%)
methods for sampling animals:
- visual counting
- aerial photographs
- non lethal traps
main method of sampling for capture recapture:
- pooters
- nets
- pitfall traps
lincoln index use
used to estimate population size. aka capture recapture. not a sampling technique
what is the lincoln index method?
- safely capture organisms using pooters, nets or pitfall traps
- mark them in a way that does not cause harm or predation bias
- release them
- repeat the sample the following day/week
- calculate population size
how to calculate population size with lincoln index?
(n1 x n2) / m2
n1 = number collected in first capture
n2 = number collected in second capture
m2 = number of marked in second capture
limitations of lincoln index
- can only be used on mobile organisms
- based on assumptions that there was no immigration, emigration, hibernation, births or deaths