RPQ 12 - investigate effect of environ factor on dist

• the distribution of species often changes within a particular area

  e.g. might find more shade-loving plants at the edge of a field where they are sheltered by a tree, than in the centre where they are exposed to full sunlight

  to find the effect of an environmental (abiotic) factor on the distribution of a species you need to carry out a carefully planned investigation
• could investigate the effect of soil pH on marram grass in a coastal ecosystem
• method:

  1. place a tape measure in a straight line from the shore, heading inland - this will be your transect
  2. take a 1 m2 quadrat divided into 100 squares (10 by 10)
  3. starting from the shore, place the quadrat next to the tape measure - doesn't matter where position quadrat relative to tape measure as long as do it the same way each time
  4. count the squares containing marram grass and record the result in a table as % cover. if have time take 2 repeat quadrat samples next to initial quadrat and take a mean of results - could take a mean of the data of your whole class
• 1. at each sample point, should also measure the pH and record the results in the table
  2. repeat observations every 10 m along the transect
• measuring pH:

  • could use a digital pH probe to take the pH readings of sand/ soil in the field
  • if not - take a sample - sieve to remove any debris, like twigs and leaves and place in a test tube
  • add some barium sulfate, distilled water and pH indicator
  • shake thoroughly and leave to settle
  • check colour against a pH chart and record the result
• pH should decrease as you move inland -

  • near the shore the sand/ soil contains a lot of shell fragments - made of calcium carbonate - alkaline compound
  • further inland - rotting vegetation adds organic matter to the soil - more acidic
• ethical issues:

  • all fieldwork affects the environ where it is carried out e.g. lots of people walking around may cause soil erosion and marram grass can be killed by people trampling all over it
  • investigations should be planned to have the smallest impact possible e.g. people should restrict where they walk to the area being studied and try to avoid treading on the plants themselves
• safety issues:

  • when carrying out fieldwork - expose yourself to risks
  • need to think about what risks you'll be exposed to so can plan ways to reduce the chance of them happening - risk assessment
  • e.g. in this investigation - use tide timetables so you know what the local tide times are - low tide is best to work on a beach
  • make sure to wash hands before eating - especially after handling soil
• falls and slips:

  • wear suitable footwear for the terrain e.g. wellies on wet or boggy ground and sturdy shoes on rough terrain to help stop you slipping
  • make sure the study area isn't near any cliffs or on steep ground
• weather:

  • check the weather forecast beforehand and take precautions
  • e.g. wear warm clothing on cold or wet days and on hot days wear a sun hat and apply sun cream
  • if the weather is too severe - do the fieldwork another day
• stings and bites:

  • wear insect repellent, or if you have an allergy - take medication with you
• a kite diagram shows the distribution and abundance of organisms along a transect:

  • the thickness of the kite shape shows the abundance - the thicker the kite shape, the more organisms there are