Sampling Techniques Flashcards
Name the abiotic factors
Moisture
Light intensity
pH
Temperature
Name the biotic factors
Grazing Predation Disease Competition for resources Food availability
How do you measure moisture?
What are the possible sources of error?
Precaution to reduce errors?
Moisture meter
Moisture from a previous reading may be left on the probe and effect the next reading.
How do you measure light intensity?
What are the possible sources of error?
Precaution to reduce errors?
Light meter
The observer may cast a shadow on the light meter.
Stand well back form meter.
Light intensity may change depending on cloud cover.
Take all readings as near to the same time as possible.
How do you measure pH?
What are the possible sources of error?
Precaution to reduce errors?
pH meter
Soil from a previous reading may be left on the probe and give a false result.
How do you measure temperature?
What are the possible sources of error?
Precaution to reduce errors?
Thermometer
Probe may remain at the previous temperature.
Allow probe to return to air temperature between readings.
What does tree beating measure and how do you use it?
The number of organisms in a tree.
Beat a tree with a stick and catch the organisms that fall out in a tray.
What does a pitfall trap measure and how do you use it?
The number of small invertebrate animals living on the soil surface. Dig a hole in the ground and place a cup in it making sure you don’t have space down the sides for organisms to fall down.
What does a tullgren funnel measure and how do you use it?
The number of organisms in a soil sample.
Place soil sample on a sieve that lets the organisms through so they fall into a tub and a bright light above to attract them out.
What does a water net measure and how do you use it?
Number of organisms living in a fresh water pond.
Place water net in fresh water pond and capture organisms that swim into it.
What does a quadrat measure and how do you use it?
Number of low growing plants in a field and very sow moving animals.
Throw the quadrat into an area of field and count the number of squares that contain the certain plant you are measuring.
How do you minimise errors when using a quadrat?
Throw randomly and several time to increase reliability.
How do you minimise errors when using a pitfall trap?
Disguise opening
Place pitfall trap deep in ground level with the surface.
How do you minimise errors when using tree beating?
Use a large tray with raised edges
Collect remaining organisms by hand.
How do you minimise errors when using a tullgren funnel?
Use a mesh with larger sized holes.
Make a thin layer of soil.
