Environmental science Paper 1

• What are the general principles of scientific investigations


  identifying topic of interest

  finding out what has already been learnt

  formulating a hypothesis

  designing and carrying out new experiments

  designing an investigation

  analysing the results and drawing conclusions

  planning further research
• What should be considered when designing an investigation


  location of sampling sites

  number of sampling sites

  size of samples

  standardised technique

  timing of sampling

  statistical analysis
• When do you use random sampling

  if the study has a regular shape, a grid can be laid out and coordinates of sites are randomly selected
• What is systematic sampling

  involves samples taken from a chosen interval distance of spacing

  the choice of sampling sites is not based on choice made by observable differences
• Why do you use sample timing


  To ensure data variability is detected. Selection of time intervals between samples
• How do you know how big your sample should be


  Dependent on sample homogeneity.

  mainly the larger samples will be more representative
• What number of samples should you use


  a larger number will be more representative

  but Dependent on data variability.

  To enable analysis of statistical significance.
• Why should you standardise techniques


  To allow comparisons between different studies/ ensure consistent reliability
• How do you select quadrat size


  depends on the habitat and groups of species being studied

  e.g. lichens 10cmx10cm

  ground flora 0.5mx0.5m
• What are the different types of quadrat

  open frame quadrat

  grid quadrat

  point quadrats
• What are the limitations of quadrates

  subjective judgment may be involved

  the frame may latten or move plants
• What is the method of a pond net


  Swept through the water of aquatic vegetation to capture organisms

  using particular length of sweep and number of sweeps can be used to standardise results
• What are limitations of pond nets

  Mobile species may escape
• What is the method of kick sampling


  a net is help with is straight edge on river bed

  riverbed Infront of bed is disturbed by scarping boot and dislodged invertebrates are caught

  controlling number and length of kicks can standardise the results
• Limitations of kick sampling


  accurate standardisation is difficult

  buried organisms or those fixed on stones may not be dislodged

  some organisms can swim and avoid the net

  the water flow rate is variable and affects capture rate

  fragile organisms could be destroyed
• Method of using Surber samplers


  fixed areas is sampled with a box like frame

  the riverbed is disturbed using a trowel or similar tool and stones are inspected manually

  netting at the sides of the net opening reduces the number if organisms that escape
• Limitations of a Surber sampler


  can only be used where water flow is fast enough to flow into the net

  the size may make it difficult to set on rough ground
• Method of using sweep nets


  are sturdy nets used to sample invertebrates in ground vegetation, the net is swept through the vegetation so organisms dislodged are caught

  standardisation can be using the same amount of sweeps at the same length
• Limitations of sweep nets

  mobile species mat escape
• Method of using colonisation media


  some species can be monitored by providing suitable habitats that they may colonise
• Limitations of using colonisation media


  not all species can be monitored as they may not use the media

  accurate population estimates are bit possible as the proportion that colonise media is not known
• Method of using pitfall traps


  a container is placed in a whole in the ground with its open end making a close fit with the soil and the top being level with the ground surface

  a cover is supported over the opening to exclude predators that may eat animals that are caught and prevent flooding by rain

  the trap is checked after standard period of tie

  a preservative fluid may be used to kill captured animals for later study
• Limitations of using pitfall traps


  only mobile animals that living on grounds surface are caught

  more mobile species are more likely to be caught

  trapped carnivorous animals may kill other organisms that have been caught

  if preservative is used it may attract or repel certain species

  some species can avoid the trap or can escape
• Methods of using beating tray

  a sheet of tray is placed beneath the vegetation which is beaten several times with a stick, the invertebrates that are dislodged fall onto the sheet and are collected for identification and counting
• Limitations of beating trays


  difficult to standardise the method

  some species will not be dislodged

  thicker branches shake less

  some species fly away and are not caught

  higher branches cannot be reached
• Method of using light traps


  flying insects, especially moths that are attracted to the light fall into a container, the container is checked in the morning

  the insects caught are identified and counted
• Limitations of using light traps


  moths only fly during adult phase and activity is affected by the weather and seasons

  the brightness and wavelength of light can affect the attractiveness to insects
• Method of using Tullgren funnel


  a sample of leaf litter or soil is placed on a mesh beneath a light

  the light and heat repel some mobile invertebrates which move downwards, pass through the mesh and fall into the container

  the Tullgren funnel is left operating for a standard period of time

  the invertebrates are collected identified and counted
• Limitations of using a Tullgren funnel


  only species repelled by light or heat will be collected

  some organisms may die or stop moving due to heating or desiccation before they are collected

  some organism are too large to pas through the mesh
• Method of using suction samplers


  several differ t types for the ground, vegetation an atmosphere

  air suction samplers can capture flying insects

  motor driven suction samplers can be used to sample invertebrates on the ground

  a pooter is suction sampler used to pick up invertabrates that have been found
• Limitations of using suction samplers


  some invertebrates are not caught by air sampler

  they may sense the air sampler and fly away

  same insects may not be dislodged from vegetation by a suction sampler
• What are the two methods to remove earthworms from the soi,


  soil flooding

  soil pit extraction
• What is the method of soil flooding to remove earthworms from soil

  mark out area

  remove vegetation

  add irritant solution e.g. mustard solution

  keep adding until soil is saturated

  saturate the surrounding area

  add more as it infiltrates soil

  collect worms that come to the surface

  continue collecting until no more worms come to surface

  count/ identify worms
• What are the limitations of soil flooding to remove earthworms from soil


  irritant solution may not percolate through impermeable soils

  irritant solution may not reach deepest worms

  worms may move sideways or down

  worms may not move

  worms may die

  worms may move too slowly
• What is the method of soil pit extraction to remove earthworms from soil

  a pit of a chosen area and depth is dug

  the soil is hand sorted and worms collected
• What are the limitations of soil pit extraction to remove earthworms from soil

  smaller worms may be overlooked

  digging may disturb worms which move sideways or down
• What is the DAFOR scale

  Dominant, abundant, frequent, occasional, rare
• What is species richness/ diversity


  measure of the number of different species in a specific area,
• What is species frequency


  measure of the dispersal of a species by recording the proportion of all sample s in which it was found

  a high species frequency shows the species is generally distributed
• What does species density mean

  relates to a number of species found to a specific area and makes species richness results more comparable