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COSMOS Summer 2009:

Global Change Chemistry & Biology


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In this activity, we will study the organisms and environment along a gradient from the edge of a marsh to the top of the hill.


  • Evaluate small scale gradients in biological and environmental conditions along a transect.
  • Create graphical summaries of the findings
  • Enter data into class database [link to google doc]


The UCI Arboretum map of UCI Arboretum


  • GPS device
  • TDR probe for measuring soil moisture
  • Meter stick
  • LICOR LI-800 gashound, with chamber for measuring soil respiration, 12V battery, and pump
  • Clippers for harvesting aboveground plant biomass
  • Trowel for harvesting roots
  • Water bath for rinsing roots
  • Portable scale for measuring plant biomass


Class will survey a 100m transect at 20m intervals. Five groups of four will take turns conducting the following measurements:

  1. Soil CO2 efflux
  2. Aboveground plant biomass
  3. Root biomass
  4. Soil Moisture and insect biomass
  5. Plant diversity


  • Measure soil moisture with TDR probe
  • Measure soil temperature using thermometer


Insect Biomass

  1. take a soil core and place it in a bin
  2. mix the core well
  3. pairs of students should place a portion of the soil and count the number insects in each group
  4. after counting an insect, place it in a pre-weighed tube
  5. weigh tubes with insects from each group and record
  6. subtract original tube weight from weight of tube plus insects, this is the insect biomass



  1. Clip plants along a 150 cm by 10 cm strip at ground level.
  2. weigh plants and record mass


  1. Create a spreadsheet based on this template:
  2. Fill in data for each sample site
  3. Calculate biomass of plants and insects in units of g or mg per m2

Graphical summary

Graph plant and insect biomass, soil temperature, and soil moisture on a chart. Here is an example; example transect results


  1. Look at your graph and describe the patterns that you see
  2. Are plant and insect biomass correlated along the gradient?
  3. How are soil temperature and soil moisture related to plant and insect biomass?
  4. What other patterns did you see?
  5. Why do you think that these patterns exist?


Write a one paragraph summary of your analysis.