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 ECOLOGY : FIELD TRIP TO CORREZE

COMPARING THE RELATIONSHIP BETWEEN TWO ABIOTIC FACTORS

In ecology it is important to collect information on the various abiotic factors that will influence the living organisms being studied.

First you must decide on which factors are the most significant. There is no point in measuring everything. You may also be limited by the instruments at your disposal.

You may wish to determine how one abiotic factor influences another at the sites where you are sampling. (e.g. light verses temperature).

Materials

Tape measure or string marked in metres

TI Graphing Calculator with DataMate program installed
CBL2 interface

Any two of the following probes:

  • Temperature probe
  • Light probe
  • Humidity probe
  • Conductivity probe
  • Flow rate probe

Starting the DataMate Program and setting up

  1. Use the following steps to start the DataMate program on your calculator:
    Press , then press the calculator key for the number that precedes DATAMATE. Press . An introductory screen will appear, followed by the main screen.
     
  2. Plug one of the probes into channel CH 1 and the other in channel CH 2 on the CBL2 interface.
     
  3. Start the DataMate program. Press to reset the program. DataMate will detect the probe and display the current sensor reading.

  1. Press 1: SETUP and using the cursor buttons, or (be patient it’s a bit sluggish!)
    select MODE press (scroll up to get to the last item on the menu).

 

  1. In the SELECT MODE menu press 5: SELECTED EVENTS.
  2. Press 1: OK to return to the main screen.

Collecting data
  1. Set the probe in position for measurement, take care that you are not influencing the measurement.

  2. Select : START to begin data collection. Press to record your measurement. Then move to the next sampling site. Press again.

    You should aim to collect at least 10 data points then press key to stop sampling

Analysing the data
  1. Return to 1: MAIN SCREEN. Then select 3: GRAPH.
    For a scatter graph of the two variables select CH2 VS. CH1 using the cursor and press .

Describe the overall shape of the line set out by the scattered points on the graph. (Is it linear or curved? Which way does the trend go?)
  1. You may even analyse the scattergram by plotting a linear regression line. Return to 1: MAIN SCREEN. Press 4: ANALYSE, then 2: CURVE FIT, then select 6: LINEAR (CH2 VS CH1).

  1. To store your data, if you are satisfied with it, return to the main screen by pressing .
    Press 5: TOOLS, then select 1: STORE LATEST DATA RUN. This stores the data in lists. In this case CH1 in L1 and CH2 will be in L2 with a copy of it in L3.
    To check this press 6: QUIT, then , then and then select 1:EDIT…You will see a spread sheet with your data in it in L1, L2 (and L3).
MOST IMPORTANT Storing your data in the calculator’s archive

If you do not do this your data will be lost. The next time you use a spread sheet the data in L1, L2 etc. will get compressed.

Archiving frees up RAM memory so that you can continue recording more data. Archiving data will remove it from the RAM memory but it will not stop it from being over-written when new data is recorded. It needs to be renamed.

To rename a list of data (e.g. L1)

  1. Select the list to be stored by pressing then then
  2. Open the LIST menu by pressing then LIST and select OPS using the cursor
     
  3. Descend the menu using the cursor to B: L press and type in a code name for the list. It must start with a letter so press the green key and chose a letter. Your list name can consist of one letter and four figures (try today’s date)

To archive or un-archive a list variable (L1) using a Memory Management editor:
  1. Press then MEM to display the MEMORY menu.
  2. Select 2:Mem Mgmt/Del... to display the MEMORY MANAGEMENT/DELETE menu.
  3. Select 4:List... to display the LIST menu.
  4. Press to archive L1. An asterisk (*) will appear to the left of L1 to indicate it is an archived variable.
    To unarchive a variable in this screen, put the cursor next to the archived variable and press     . The asterisk will disappear.
  5. Press then QUIT to leave the LIST menu.

© Paul Billiet 2004