Lesson 12 - Sampling techniques Flashcards
Ethics of collecting living animals:
- Handle for a short period of time
- Must be released back into habitat at the point they were collected.
Techniques to collect living animals:
- A pooter –> small insects.
- Sweep nets –> insects in areas of long grass
- Pitfall traps –> crawling invertebrates such as beetles, spiders and slugs.
- Tree beating –> Take samples lining in a tree or bush.
- Kick sampling –> study organisms living in a river.
Pooter:
- Small insects
- Suck into mouthpiece, insects drawn into the holding chamber via inlet tube. Filter before the mouthpiece prevents them from being sucked into the mouth.
Pitfall traps
- Small, crawling invertebrates (beetles, spiders and slugs)
- Hole is dug into ground, which insects fall into.
- Deep enough that they cannot crawl out, covered with a roof-structure propped above so that trap doesn’t fill with rainwater.
- Traps are left overnight, so nocturnal species also sampled.
Tree beating:
- Invertebrates living in tree / bush.
- Large white cloth stretched under tree. Tree is shaken / beaten to dislodge invertebrates. Animals will fall into the sheet where they can be collected and studied.
Kick sampling
- Organisms living in a river.
- River bank and bed is ‘kicked’ for a period of time to disturb substrate. Net held downstream for set period in order to capture organisms released into flowing water.
Sampling plants:
- Quadrat –> pinpoint an area in which the sample of plants should be collected.
- Samples can also be used to sample slow-moving animals.
Types of quadrat:
- Point quadrat –> frame containing horizontal bar. At set intervals, long pins can be pushed through bar to reach ground. Each species of plant the pin touches is recorded.
- Frame quadrat –> consists of a square frame divided into a grid of equal sections. Type and number of species within each section of quadrat is recorded.
Valid representative of an area (quadrats)
Random sampling technique
Presence and distribution of organisms across an area of land varies (quadrats)
line / belt transect.
Measuring species richness:
- Biodiversity species richness is a measure of the number of different species living in a specific area.
- Combination of techniques.
- List of species complied and identified. (Identification keys used - contain images / series of questions)
- Total no. species calculated.
Measuring species evenness:
- How close in numbers the populations of each species in an environment are.
Using frame quadrats:
- Density –> no. large plants in 1m by 1m quadrat square.
- Frequency –> Individual members of species hard to count. Use small grids within quadrat.
- Percentage cover –> Speed as lots of data collected quickly. Estimate by eye of area within quadrat that species of plan species covers.
The larger the number of sample taken…
the more reliable your results.
Estimating animal population size:
- Moving / hidden.
- Capture-mark-release-recapture.
- Compare number of marked individuals with the number of unmarked individuals in the second sample –> estimate population size.
- Greater the number of marked individuals recaptured, the smaller the population.
How is species evenness expressed:
As a ratio
Measuring abiotic factors:
- Range of sensors
Advantages of using sensors:
- Rapid changes can be detected.
- Human error in taking a reading reduced.
- High degree of precision can often be achieved.
- Data can be stored and tracked on a computer.
Wind speed sensor used and units?
Anemometer –> m s^-1
Light intensity sensor used and units?
light meter lx
Relative humidity sensor used and units?
Humidity sensor mg dm^-3
pH sensor used and units?
pH probe pH
temperature sensor used and units?
temperature probe (degrees Celcuis)
oxygen content in water sensor used and units?
dissolved oxygen probe mg dm^-3
