Field Notes

When: Apr 26, 2002, Friday
Where: Tonzi/Vaira Ranches
Who: Liukang Xu & Jianwu Tang

Weather: 9:50 arrived at Tonzi Ranch, heavy cloud, light rain but stop shortly after, air temperature around 15-17^oC. Oak leaves are much green than last week.

Overall all the instruments were running smoothly, except the floor flux system which was not running from d1140630 to d1150500. The reason is not related to the battery power problem, since it was sunny on d113. The problem has to be caused by those unknown reasons as we experienced last summer.

Most of oak leaves looks like fully mature and grass are at the middle of senescence phase.

Trip Purpose: Check 3 flux systems, download data, soil moisture point sensor reading, grass height measurement, Dendrometer reading, A/Ci curve for oak leaf, soil and oak stem respiration measurement.

Soil moisture point sensor reading;

Soil moisture depleted very fast for the whole soil profile at Vaira and soil surface at Tonzi Ranch.

Dendrometer reading

From the Dendrometer reading, the trees are still expanding.

Grass height measurement at Tonzi Ranch (n=30, m=20.0 cm, std=7.9cm).

Tower flux system: Fence working, flux gillsonic was running,

Download data, PV reading, 13.8V, 9.7A and 2.3A, battery half full.

Floor flux system: Fence working, flux program was running, But from d1140630-d1150500, no flux data. Since it was sunny on d113, I assume that the flux program was frozen at that time not due to the power problem. PV reading 13.1V, 3.2A and 1.9 A, battery fully charged.

A/Ci Curves: Finished 3 A/Ci curves for oak leaf. Took some oak leaves samples for leaf development analysis. Oak leaves are much greener than last week.

Jianwu did soil and stem respiration measurement.

Vaira Ranch: Arrive at 1:45, heavy cloudy, clover purple flower, grass leaf color start turn to yellow.

Fence working, flux program was running good. Download data

Gillsonic output;

PV reading; 12.0V, 0.88A, and 2.9A; battery charge was low, red light flashing.

Soil moisture point sensor reading, see above for results.

Grass height measurement;(n=30, m=40.7cm and std=10.86).