BIOL 329 Lecture 3: BIOL 329 -Lect 3
6 May 2018
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Lect 3
Beginning to consider habitats as part of the species at risk. BUT why do we keep added species to the
red list? Habitat gets sacrificed over and over.
E.g. marbled diawep (?)
What is sampling?
A way of collecting observations. Random of systematic = representative Independent. Replicated –
more samples better than few. Extrapolate results to estimate total population size.
E.g. Red-nape sap suckers. Random sample should represent the population.
Random sampling: carried out when the area under the study is fairly uniform, very large, and/or there
is limited time available. Grid the area and randomly select which grids to sample. When using random
sampling, large numbers of samples/records are taken from different positions within the habitat. A
quadrat frame is most often used for this type of sampling quadrats aren’t great for mobile species
(e.g. birds).
Systematic sampling: samples are taken at fixed intervals, usually along a line. Involves transects, where
a sampling line is set up across areas where there are clear environmental gradients. Species touching
the line may be recorded along the whole length of the line (continuous sampling). Or, the presence,
absence of species at each marked point is recorded __________
Stratified sampling: to take into account different areas (or strata) which are identified within the main
body of a habitat.
Sampling error: the chance difference between an estimate and the population parameter being
estimated. Ideally, our estimate is accurate and precise (unbiased). If samples are not properly taken...
Sampling bias: systematic discrepancy between estimates and the true population characteristic and is a
result of a poor sampling plan.
Document Summary
Beginning to consider habitats as part of the species at risk. Random sampling: carried out when the area under the study is fairly uniform, very large, and/or there is limited time available. Grid the area and randomly select which grids to sample. When using random sampling, large numbers of samples/records are taken from different positions within the habitat. A quadrat frame is most often used for this type of sampling quadrats aren"t great for mobile species (e. g. birds). Systematic sampling: samples are taken at fixed intervals, usually along a line. Involves transects, where a sampling line is set up across areas where there are clear environmental gradients. Species touching the line may be recorded along the whole length of the line (continuous sampling). Or, the presence, absence of species at each marked point is recorded __________ Stratified sampling: to take into account different areas (or strata) which are identified within the main body of a habitat.
