Investigating Ecosystems Flashcards
How do you place a quadrat?
Map out study area
Draw grid on area, smaller squares for smaller organisms
Number each square
Use random number generator to choose which squares to sample
Gather all biomass in area
Dry until weight doesnt change
What is a quadrat?
Frame of a specific size (depending on what is being studied) which may be divided into subsections.
When do you use random and when do you use stratified?
You use stratified when there is an obvious difference within an area to be sampled and two sets of samples are taken.
How do you take a stratified sample?
Deal with each area separately
Draw a grid for each area
Number the squares in each area
Use random number generator to decide which squares to sample in each area
What is a transect?
A sample path along which you record the occurrence and/or distribution of plants and animals in a particular study area.
When do you use systematic sampling?
When you are looking at changes along an economic gradient.
What is a line transect?
Consists of string or measuring tape which is laid out in the direction of the environmental gradient and species touching the tape or string are recorded.
What is a belt transect?
A strip of chosen width running through an ecosystem. It is made by laying two parallel line transects. The organisms between are recorded.
What is a continuous transect?
The whole line or belt is sampled
What is an interrupted transect?
Samples are taken at points along the line or belt. Quadrats are placed at intervals along the belt.
Outline a method for measuring an abiotic factor along an environmental gradient:
Abiotic factor: turbidity
Environmental gradient: along a slope in a pond so ranging shallowness
Method:
Measure the depth of that area of pond
Lower secchi disc until it disappears from view
Read the depth of the graduated rope.
Repeat.
Average results.
Repeat at areas of the pond that are deeper and shallower.
