Fieldwork
- Created by: elen roberts
- Created on: 23-01-14 16:32
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- Fieldwork
- Sampling
- Random sampling
- Representative sample around 2% of the area
- Measuring tapes placed around the area to create a grid and numbers are randomly generated to make coordinates
- Large no. of samples, at least 10 to minimise chance of skewed sample or anomalies
- Systematic sampling
- choose where to take samples to measure a pattern
- Transect
- Samples taken along a line to see what changes occur
- Line Transect - organisms touching the line along the transect are recorded
- Quickest
- Belt transect - quadrats placed at intervals along transect and animals in quadrate are counted
- Generates more complete data
- Presented in kite graph showing biotic an abiotic factors
- Both abiotic & biotic should be measured at each site for better understanding
- Random sampling
- Diffucluties
- Large number of organisms
- Confounding variables such as weather
- Organisms may be hard to find or identify
- Measuring Abiotic factors
- Measured with special digital electronic equipment which are quick, quantitive, accurate, calibrated and automatically recorded
- In a terrestrial habitat - air temp., light intensity, wind speed & direction.
- Each abiotic measurement should be repeated several times and averaged
- Measured over a day or a year to account for daily and seasonal variations
- Aim to correlate abiotic and biotic measurements at the same points to find a causal relationship
- Measuring Biotic factors
- Identification usising identification key
- Quantitive measurements
- Abundance
- Counting number of organisms.
- Richness
- Number of different species in the sample
- Diversity
- Divide abundance by sampling area better measure in Simpson Diversity Index - richness & abundance
- Growth
- Comparing growth or size of similar organisms in different habitats
- Biomass
- Dry Mass - organisms much be heated to 80o to evaporate water but not burn organic material. Sample is weighed at intervals until changes stop
- Productivity and pyramids come from measuring dry mass
- Abundance
- Sampling Plants
- Quadrats
- Preliminary experiment to find best size quadrat
- Species area graph
- Quantitive
- Preliminary experiment to find best size quadrat
- Density - individuals in each area/area of quadrat
- Cant be used on plants hard to identify.
- Species frequency - No. of quadrate species were found in.
- % cover - estimated and inaccurate due to layers of plants and easier if quadrat is sub decided. Used when plants are hard to identify
- Point Quadrat - % cover - species hit by needle are recorded and repeated. Hits/repeats give % cover
- Abundance scale - Quantative - ACFOR. Can be made quantative by corresponding %.
- Quadrats
- Sampling Animals
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- Sampling
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