Ground-dwelling arthropods

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ARTHROPOD PROJECT

Contents

Introduction

We will sample leaf litter to test the hypothesis that there are more ground-dwelling arthropods in closed canopy rain forest than in gaps. Leaf litter under a forest canopy is less likely to be affected by environmental disturbance and temperature extremes, thereby providing a more stable habitat.

  • H0: There are no differences in the diversity of ground dwelling arthropods found in the rainforest compared with those found in gaps.


Methods

Sample arthropods using pitfall traps and leaf litter samples under the canopy and in tree-fall gaps in primary rain forest at Lambir.

  • Location of sample sites:
    • Treatment 1 – Gap - random walk within a gap identified by Sylvester.
    • Treatment 2 – Rainforest – select a site that is a fixed distance and fixed direction from the randomly selected gap.
  • Leaf litter:
    • Mark a 0.5 x 0.5 m2 leaf litter sample quadrat.
    • Measure litter depth from the top litter layer to the soil surface in the middle of the sample quadrat with a ruler.
    • Using your gloved hands and a trowel, collect all litter and the top 1 cm of soil into a plastic bag.
    • Label the sample!
  • Sorting in the lab:
    • Empty a sample into a Winkler sifter to a depth of no more that 6”
    • Shake/twist the sifter for 60 seconds
    • Repeat until all litter in the sample has been sifted
    • Empty the pre-sorted sample into a new plastic bag
    • Label the sample!
    • Pour the sifted litter into a white tray so that the tray can be faintly seen through the litter.
    • Two people should attempt to remove all arthropods with tweezers/pooter/hand (gloves) and place in petri dish with ethanol, taking no more than 3 minutes/tray.
    • Label the Petri dish!
  • Pitfall traps:
    • Mark out an ‘X’ with 5 points 50 cm apart.
    • Use auger/post-hole digger/trowel/crow bar to dig hole.
    • Embed plastic cup in ground so that rim is level with surface (do not have any part of the cup protruding above ground level!).
    • Fill half of the cup with soapy water.
    • Place a hat over top of trap (hat made from cardboard and 4 nails).
    • Demarcate pitfall area with flagging tape.
    • Record sample site number.
  • Morning of day 2:
    • Empty pitfall traps from each site into plastic container - six containers in total.
    • Remove pitfalls, fill in holes and scatter leaf litter; remove flagging tape.
    • Label sample number/site on container.
  • Identification of arthropods:
    • Decant contents of the pitfall samples into petri dish for sorting.
    • Under microscopes, identify arthropods to order. For ants, Dave will help identify to genus using key to ants of Borneo.
    • Tally numbers for each order.
    • Enter data from sample into spreadsheet for each sample.
    • All take turns at sorting/identification.


Equipment list

  • Pitfall sampling
    • Post-hole digger, crowbar
    • Hand trowels, secateurs (pruning shears)
    • Two containers filled with water-detergent mix
    • 30 plastic cups
    • 30 cardboard hats
    • 120 x 4” nails
    • Flagging tape
    • Tape measure
    • Sealed containers for carrying back insects
  • Litter sampling
    • 50 cm2 PVC pipe quadrat marker
    • Six plastic bags for litter
    • Two rulers
    • Two pairs of gloves
  • Lab
    • Five field microscopes, one binocular microscope
    • Bench lamps
    • Hand lens
    • Gloves
    • Squirt bottles
    • Forceps
    • Pooter
    • Petri dishes
    • Ethanol
    • Plastic pipettes
    • Tally sheets, pencils, etc.

Results

Download the data here (right click, `Save as').