Field Notes

When: May 2, 2002, d122 Thu
Where: Tonzi/Vaira Ranches
Who: Liukang Xu
Weather: 9:15 arrived at Tonzi Ranch, Sunny, temperature 16-20^oC,

Trip Purpose: Check 3 flux systems, download data, soil moisture point sensor reading, grass height measurement, Dendrometer reading, grass LAI sample at Varia and Tonzi ranch, A/Ci curve for grass at Tonzi Ranch.

Overall all flux systems were running smoothly. No power for electric fence at Vaira, fortunately no cow breaking in. It appears that the wire of electric fence was short circuited to the ground via fence poles by bird poop. Apparently bird poop mixed with enough rainfall water could be a conductible material, believe it or not! After I replaced a fully charged battery and replaced some of dirty yellow plastic connector, fence works fine.

It is a good idea always to have a fully charged battery at each site, in case we need it for fence or watchdog !!!

Tonzi Ranch: By judging from the dark green color, oak leaves are fully mature. The grass in the open space senesces early than those under oak tree. Finished 3 A/Ci curves for broad leaves at Tonzi ranch near floor met station.

Floor flux system: Fence and flux system were running continuously, gillsonic output are as follows;

PV reading, 13.4V, 1.0A (this number is jumping around 0.1 to 1.0, maybe the battery is fully charged, or something wrong with the PV controller?), and 1.9A. Battery fully charged.

Tower system: Fence and flux system were running. The flux system was stop from d121 1400 to d122 0430, presumably due to the heavy cloud. PV reading 14.2V, 7.03A and 2.7A, Battery fully charged.

Gillsonic outputs as;

Soil moisture point sensor reading;

Dendrometer reading

From the Dendrometer reading, the trees are still expanding, even though the oak leaves are fully mature and very active. But last week the weather was cold and lot of cloudy day as indicated by the slowdown of soil moisture depletion.

Took 3 LAI sample from Tonzi ranch. Took some oak leave samples.

A/Ci Curves: Finished 3 A/Ci curves for grass near the floor met station.

Vaira Ranch: Arrive at 10:30 sunny. Fence battery voltage was low, I barely can feel the electric pulse. I chopped those grass touching the fence wire, replaced fence battery, replaced dirty (by bird poop) yellow plastic connector, the electric fence was back to work, flux program was running good. Download data

Gillsonic output;

PV reading 12.8V, 11.1A and 3.3A, red light flashing. After I cut the grass that blocking the sunlight for the two bottom solar panels, current increased by 2.0A.

Soil moisture point sensor reading, see above for results.

Grass height measurement;(n=25, m=55.0cm and std=12.10).

Took three LAI samples.