New Page 0

Troubleshoot

Some suggestions to avoid mistakes and to make it easier to get accurate data...

As a suggestion for the 1/2 x 1/2 m² plots in which centipede tests need to be conducted (see Procedure), PVC pipe constructed in squares works very well to lay down on the ground and dig within.
Always wear gloves when dealing with centipedes, they can bite.
Make sure each centipede is not counted multiple times, this can be avoided by putting dirt in a bucket as it is taken out of the ground.
Make sure centipedes are being counted and not millipedes, as they can look similar. (Millipedes have a more rounded body and legs tucked under their body as well as two pairs of legs per body segment, not one.)

http://www.enchantedlearning.com/subjects/invertebrates/arthropod/Centipede.shtml

http://www.enchantedlearning.com/subjects/invertebrates/arthropod/Millipede.shtml

If you find that your p-values as a result of T-testing are high, a Densiometer can be used to corroborate your data
- To create: take a tube of diameter, 4 cm and length 7.5 cm. Attach 2 strings to cross perpendicularly over the top and on the other end attach an 18 cm piece of string with a metal nut hanging from it (shown below)
http://www.globe.gov/globe_flash.html
- look up through the densiometer making sure the metal nut is below the intersection of the perpendicular strings, and calculate the percentage of the circle in which the canopy cover is seen
- holding the densiometer at waist level look down into it, making sure the metal nut is directly below the intersection point of the 2 strings, calculate the percentage of the circle in which ground cover is seen
  - Use the 4 divided sections to estimate the percent covered by plants
- This can help to determine whether plant density is a determining factor in centipede populations
Make sure if a densiometer is made that the string with the metal nut is secured very tightly, ours fell off

Densiometer Before	Densiometer After