Field Notes

<--2017-07-12 12:30:00 | 2017-08-02 11:36:00-->
Other sites visited today: Mayberry | East End | Sherman Wetland
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West Pond: 2017-07-19 09:45:00 (DOY 200)
Author: Daphne Szutu
Others: Elke Eichelmann, Ada Chang

Summary: Regular data collection and cleaning, trimmed vegetation by tower/boardwalk, eosense CO2 sensor maxing out at 5V, took Li-6400 photosynthesis measurements

2017-07-19
West Pond

We arrived at 9:45. Elke and Ada stayed here during the day taking 6400 measurements. It was sunny and clear with a light breeze. The water level at WP seems generally low. I trimmed some of the cattail and tule by the tower and boardwalk.

I collected met, camera, and USB GHG data. The 7700 wash reservoir was 3/4 full and I refilled it.

The CO2 sensor has been around 1200 mV, but starting around Jul 13 it began consistently maxing out at 5000 mV (the top of its range). It was about 1/2 submerged in the water, so I did not lower it farther. It is one of the lightly refurbished sensors eosense had sent us and we had just deployed it .

LI7500 readings:
CO2 = 401.7 umol/mol
H2O = 641.2 mmol/m3
T = 24.0 C
P = 101.1 kPa
SS = 96.5 --> 98.1 after cleaning

LI7700 readings:
CH4 = 1.94
RSSI = 50.3 --> 81.2 after cleaning

I cleaned the EC and radiation sensors. There were many spiderwebs around the EC sensors.

NDVI in: sn 1066703780
NDVI out: sn 2046503378

I left at 10:55.

------ LI-6400 photosynthesis measurements ----------
We used the borrowed LI-6400 from Whendee Silver's lab with our slightly modified clear conifer chamber head for leaf level photosynthesis and water exchange measurements.

Sophie Taddeo from Iryna Dronova's lab arrived at West Pond with a few helpers around 10am. They were doing a survey of West Pond looking at standing biomass, species composition, LAI, etc.

We matched the IRGAs at start at 10:27 at a CO2 concentration in the reference cell IRGA of 235.9.

We took 21 measurements in total, although one of these was an accidental double measurement. We started measurements at 10:30 and took 5 tule measurements at first, then 5 cattail. Then we took a 30 min lunch break. After lunch at 12:15 we started again with 5 cattail and finished with 5 tule. We worked off the boardwalk next to the EC tower. Since the boardwalk at West Pond is close to water level and fairly small, we couldn't do measurements at top of the canopy light conditions. We tried to have the measurement area in full sunlight as much as we could. Also, since we were working further down in the canopy, the measurements might have been taken lower on the plants than at East End, but they were generally within the top half of the plants.

We used full bypass for both CO2 scrub and desiccant on all measurements. For all measurements we held the leafs horizontally, regardless of how they were oriented in the field. This led to some leafs being bent so far that they would show a fold. We did not take any measurements on plants that already had a fold in them before we started.

We finished the last measurement at 13:45 and left around 14:30.

Veg Height (cm): Tape measure from ground to top of plant - Green plants from 30cm x 30cm plots 7m to 10m apart along a transect upwind from the tower. From Sophie
350, 280, 270, 290, 350, 360, 320, 360, 370, 360, 180, 230, 310, 260, avg = 238.6, stdev = 82.76

0 photos found

8 sets found

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1 WP_DO graphs found