Transects & Quadrats - Conducting-A-Field-Trip-To

Report
Ecology Sampling Methods
What are they?
• Biologists need to collect data ‘in the field”
• This data needs to be collected in a
standardised way. (why?)
• Two methods of doing this are;
– Transect sampling
– Quadrat Sampling
Transects
• Transect sampling is using a
single line
• This line is stretched over
the area to be studied
• The line is positioned to
encompass the changes in a
site
• The line has regular
measurements marked on it
(like a tape measure).
• The line must be held
straight and stationary
Quadrats
• Quadrats enable
comparisons between
different areas of a
survey site
• A Quadrat is a framed
area
• The area within the
quadrat is sectioned
into a set number or
squares or intercepts
Quadrats (cont)
• Quadrats can be placed randomly, or at
regular intervals along a transect line
Types of Sampling
•
•
•
•
Point-intercept along a transect line
Visual estimate within a quadrat
Point intercept within a quadrat
Photoquadrats
Transect line
Quadrat
What to use when?
• The data collection method varies depending
on;
– The habitat
– The question of interest
– The researcher
– Providing the most accurate results
– Providing the most repeatable results
Pros and Cons
Data Type
Advantages
Disadvantages
Transect Data
•Easy
•Fast
•Good for large species
•Hard to generalise
results
•Difficult to compare
across groups
Quadrat Data
•Random placement is
fast
•Good for substrate and
large species
•Can cause biased
results
•Gives detailed
population & % cover
data
•Good for small & rare
species
•Time consuming
Point Intercept Data
References
•
•
•
•
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Association, F. M. (2007, December 13). Photo Quadrat Classroom Activity.
Retrieved October 18, 2010, from Farallones Marine Sanctuary Association:
http://www.farallones.org/education/documents/PhotoQuadActivity-legal.pdf
Authority, R. I. (2010). Experience Rottnest Island. Retrieved October 18, 2010,
from About Rottnest Island:
http://www.rottnestisland.com/en/About_Rottnest_Island/Flora_and_fauna/Page
s/Flora_and_fauna.aspx
Baumgartner, E. a. (2009). Measuring Abundance: Transects and Quadrats.
Retrieved October 18, 2010, from EECB Graduate Fellowships in K-12 Education:
http://www.hawaii.edu/gk-12/opihi/classroom/measuring.pdf
Maben, A. (n.d.). Coastal Shore Investigation. Retrieved October 18, 2010, from
Maine Intertidal Zone Investigation: http://www.bigelow.org/mitzi/CSI.html
Marine Discovery Centre, Q. (2010). Background Information. Retrieved October
18, 2010, from Intertidal Rocky Shores:
http://www.rockyshores.auz.info/back_info01.htm

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