Distribution of Organisms Flashcards
What are biotic factors?
Factors in the ecosystem that are related to biological, living things
What are abiotic factors?
Non-living factors within the ecosystem that can be measured
What are some examples of biotic factors?
Predation, grazing, food availability, disease and competition for resources
How can predation affect biodiversity?
Through predator-prey interactions
What are some examples of abiotic factors?
Light intensity, moisture, temperature and pH
How do you measure light intensity?
By using a light meter
How do you measure temperature?
By using a thermometer
How do you measure soil moisture?
By using a moisture meter
How do you measure pH?
By using a soil pH meter
What are the sources of error in measuring abiotic factors?
- getting the wrong temperature reading
- causing a shadow over the light meter
- getting the pH and moisture readings to all be the same
What is the solution to getting the wrong temperature reading?
Give the thermometer time to reach the correct temperature
What is the solution to causing a shadow over the light meter?
Do not shadow the light meter
What is the solution to getting the pH and moisture to all be the same?
Clean and dry the probe before and after each use
How could we measure plant population sizes in a field?
By using quadrats and transect lines
What are quadrats used for?
To sample low growing plants (e.g. clover) by marking off an exact area of ground so that the organisms can be identified and counted
How do you use a quadrat?
- Throw the quadrat randomly
- Count the number of each species in the quadrat
- Record the results
- Repeat several times to get an average
Why would you throw the quadrat randomly?
To ensure the experiment is valid by eliminating any chance of bias by aiming for areas with lots of the species that you are measuring
Why would you repeat the experiment?
To ensure that the results taken are reliable so that any result that may not be what is expected is realised
What are the limitations of quadrats?
Quadrat Size and Species Sampled
How could you measure the number of invertebrate species in a field?
By using pitfall traps
What are pitfall traps used for?
To sample small invertebrate species living on the soil surface because species fall in and are unable to climb back out again, so they can be measured after a period of time
How do you use a pitfall trap?
- Dig a hole and place a cup in it so that the top of the cup is level with the ground
- Make sure there are drainage holes at the bottom of the cup
- Cover the top of the cup with leaves
- Repeat 5 times
- Leave for 24 hours
- Identify the species in the cup
Why are drainage holes put in the cup?
To allow water to drain out so that the invertebrate species are not harmed and that the cup doesn’t overflow with water
Why must the cup be level with the ground?
So invertebrate species can fall in which means that the species identified at the end are a better representation of the species found in the sampling area
