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15 Cards in this Set
- Front
- Back
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What is abundance?
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The number of species in a given space
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What are the two sampling methods?
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Systematic (line transect) and random (frame/point quadrat)
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What are the three factors to consider when using quadrats? (Think)
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Size of quadrat to use
The number of sample quadrats to record within the study area The position of each quadrat within the study area |
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What factors affect the size of the quadrat?
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The size of the plan being counted and the distribution
Large species --> Large quadrat Uneven distribution --> Large number of small quadrats |
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What factors affect the number of samples taken?
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The number of different species in an area (more samples = more reliable results)
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How do you carry out random sampling?
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Two long tape measures at right angles along two sides of the study area
Obtain coords using a random number generator Place the quadrat at the intersection of each pair of coordinates and record the species |
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When is systematic sampling used?
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When there is a transition in communities of plants, e.g. tidal sea shore
ZONATION is present Use a line transect |
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What are the two ways to measure abundance?
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Frequency and percentage cover
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What is frequency?
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The likelihood of a particular species occurring in a quadrat
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What are the advantages and disadvantages of using frequency to measure abundance?
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Ad: Useful if species is hard to count (grass)
Quick Dis: No information on density and detailed distribution |
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What is percentage cover?
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An estimate of the area within a quadrat that a species covers
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What are the advantages and disadvantages of percentage cover?
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Ad: Useful if species is abundant/difficult to count
Rapid Individual plants do not need to be counted Dis: Less useful when plants overlap |
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What are the assumptions of Mark-Release-Recapture?
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Proportions of marked to unmarked in second sample is the same proportion to whole population
The marked individuals distribute themselves evenly and have sufficient time to do so No immigration or emigration out of the defined boundary Few deaths/births Marking method is non-toxic nor makes the animals more conspicuous and more likely to be preyed on Mark/label does not rub off |
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How should one go about collecting data in an ecological investigation?
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Study organisms in situ - minimum disruption if necessary
Return all organisms - even dead ones Allow time before future studies Avoid damage |
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IMPORTANT:
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When carrying out fieldwork, the important thing is that there is a BALANCE between the DAMAGE done and the VALUE of the information gained
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