Sampling
- Created by: elen roberts
- Created on: 27-04-14 12:50
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- Sampling
- Random
- Large sample (2% of area)
- allow for anomalies
- Tape measures on 2 sides of the area. Randomly generated numbers form coordinates
- Large sample (2% of area)
- Systematic
- Investigating a specific pattern
- Transect
- Line transect
- The organisms touching the string layer next to the transect are recorded
- More accurate but more time consuming
- Belt transect
- Quadrats are placed at intervals and organisms in each quadrat is measured
- Faster but not as representative
- Data shown in a kite diagram - biotic = kite. abiotic = line
- Biotic & abiotic measurements at each site
- Line transect
- Abiotic factors
- Measured digitally - quick, accurate, automatic
- Measurments should be repeated and averaged
- Measured over days months and years allows for daily & seasonal changes
- Biotic factor
- Quantitive measurements
- Abundance
- Number of the organisms using mark release recapture. Abundance /sampling area = density
- Growth
- Comparing growth/sizeof similar organisms in similar habitats
- Biomass
- Dry mass shows productivity and used to make pyramids of biomass. Organisms warmed to 80 degrees to remove water and weighed until the decrease in mass stops
- Abundance
- Quantitive measurements
- Sampling animals
- Mark-release-recapture
- A sample is captured and marked in some way that will not cause harm or increase predation.
- They are then given time to mix with the rest of the population before a second sample is captured without too much time for births, deaths or migration
- Count the number captured and the number recaptured then calc. the population. 1st sample x second sample/ recaptures
- Mark-release-recapture
- Sampling plants
- Quadrat, frame quadrat, frame quadrat with grid and point quadrat
- Preliminary experiment with different sized quadrats to form a species-area graph and find the most effective size
- Quantitive measurements of the abundance of plants.
- Percentage cover - difficult to identify individuals. Estimate and most accurate with a grid quadrat
- Species Frequency - number of quadrats or squares in a quadrat containing the species
- Quadrat, frame quadrat, frame quadrat with grid and point quadrat
- Analysing samples
- Stats test give a probability (P-value) which gives the probability the results are due to chance a low P value shows significance
- if P = 0.05 any correlation is due to chance
- Use the words chance and probability
- Null hypothesis (no difference) >0.05 accept null hypothesis
- Looking for a difference (bar chart)
- Can use SD or SE and the mean, if error bars overlap theres no difference
- Looking for correlation (scatter graph)
- Correlation doesn not always mean causation, there could be a 3rd factor, a control is needed.
- Using Qualitive (categoric) data (pie chart)
- Frequencies are recorded are compared to an expected ratio
- Random
- Sampling animals
- Mark-release-recapture
- A sample is captured and marked in some way that will not cause harm or increase predation.
- They are then given time to mix with the rest of the population before a second sample is captured without too much time for births, deaths or migration
- Count the number captured and the number recaptured then calc. the population. 1st sample x second sample/ recaptures
- Mark-release-recapture
- Analysing samples
- Stats test give a probability (P-value) which gives the probability the results are due to chance a low P value shows significance
- if P = 0.05 any correlation is due to chance
- Use the words chance and probability
- Null hypothesis (no difference) >0.05 accept null hypothesis
- Looking for a difference (bar chart)
- Can use SD or SE and the mean, if error bars overlap theres no difference
- Looking for correlation (scatter graph)
- Correlation doesn not always mean causation, there could be a 3rd factor, a control is needed.
- Using Qualitive (categoric) data (pie chart)
- Frequencies are recorded are compared to an expected ratio
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