18 June, 2001
Today we will be taking diurnal measurements, the first for all of us except Glen who has been taking diurnals at his site for the last two years. A diurnal is a 24-hour time period of continuous measurements. There are 4 of us here now so Glen divided the time into four, 6-hour shifts starting at 4PM this afternoon. Michelle- 4 to 10 pm, Spring- 10pm to 4am, me- 4 to 10 am and Glen takes the last one, 10am to 4pm. The ITEX (International Tundra Experiment) group from University of Michigan is also doing a diurnal at the same time.
We hauled all the instruments, batteries and the cuvette out after lunch and went over the possible things that could happen and then all practiced with the LiCor (the portable photosynthesis system). What we will be doing is covering each circular plot with the cuvette, making sure there is a tight seal so no surrounding air can get in, turning on the LiCor and having the chamber air pass through the instrument. The instrument registers and records the amount of CO2 in the air sample. We do this 3xs. The second step is to darken the cuvette totally (we have a light proof cover) to simulate nighttime when respiration occurs and the plants give off CO2. Once again we have the chamber air pass through the LiCor and it measures CO2 in the air sample but this time we should see more CO2 being recorded. The time consuming part of this is knowing when to log in numbers. Because numbers appear on the readout panel does not mean they are significant so until we become familiar with a range of expected values we are hesitant. The difference between these two measurements, CO2 amounts from light and dark, is the flux, the measure we are looking for. Every few hours the instrument has to be zeroed out also. This insures that the LiCor has not drifted and taking measurements that are off.
If you remember the diagram of the site from 06/06 there are 3 sections and each of those sections have 6 plots that are testing a different variable: temperature (elevated or normal), soil moisture (high, low, normal) and a control. Each plot has to have the LiCor measurements record readings for light and dark three times, ideally. We each should make it around the entire site 1 and 1/2xs.
At 4pm we left Michelle at the site so we could go back and catch a nap or early bedtime. A radio is left so who ever is on site is in constant contact with Glen plus the CMDL observation dome is open (and heated) if one gets too cold. Being light 24 hours also makes being out for 6 hours easier.
Glen, Spring and I returned to NARL, our home away from home, ate dinner and caught up on sleep in preparation for our individual shifts.
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