Field Notes
<--2001-06-19 03:30:00 | 2001-06-21 07:00:00-->Other sites visited today: Vaira | Vaira
Tonzi: 2001-06-20 02:20:00 (DOY 171)
Author: Dennis Baldocchi
Others: Nancy Kiang, Jianwu Tang, Ted Hehn
Summary: Leaf water potentials measured; large nitrogen tank performing suboptimally.
| WHO: Nancy Kiang, Jianwu Tang (grad student in Ye Qi's lab) WHERE: Tonzi Ranch WHEN: Overnight at Jackson Gold Lodge, Thurs-Fri, 7/19-7/20/2001 WEATHER: Thurs 88°F, Fri 84°F, clear skies. WHAT: Measure pre-dawn and midday leaf water potentials and Leaf Area Index of transects. Fix heaters to Trees 248 and 252. Fix lower thermocouple needle to Tree 255. Jianwu Tang also measured soil respiration. 6/20/01. Arrived ~2:20 am Standard Time. 2:24-4:13 Standard Time. Measured pre-dawn leaf water potentials. 4:26-5:30 Standard Time. Measured LAI of transects T1, T2, T3. -Probably need to discard T3 data, because sun was already illuminating tops of trees, and there was sunlight and condensation on the open-area sensor by 5:30. -Clear sky. Sunrise at 5:31 am Std Time. 10:00-11:00 Standard Time. Jianwu Tang measured soil respiration. 12:04-13:40 Standard Time. Measured mid-day leaf water potentials. We measured at this time, because the previous diurnal curve showed that the minimum leaf water potential is reached during this period. 14:30-16:00 Standard Time. Jianwu Tang measured soil respiration. -Several leaves were drier than -40 bar, so we definitely need to get the -80 bar gauge by the next field visit. Comments: -Leaves on the blue oak trees are turning brown, evenly distributed throughout the tree canopy in a speckled pattern. Counted leaves on different trees to assess the percentage of senescing leaf area: Liu Kang's tree: 3/100 and 4/50 = 3-8% of leaves are brown. Tree 245 (dry tree): 14/57 and 16/59 = 25-27% Trees 71, 72, 79: less than 1% (mostly half-leaves that are brown) Tree 77: eye estimate ~20% brown Note that the brown leaves are dropping from the trees easily, so these are low estimates of the percentage of senesced leaves. The Set P trees (MD9-5, farthest from the understory flux system) are in a moister area, so they are not senescing as much. On the pine tree, the lower needles are brown, but it is not clear if this is due to water stress or simply due to the pine tree regular growth habits of senescing the lower branches as it grows. Ted: The large nitrogen tank needs to be re-filled, because it is re-filling the tanks to less than 1000 psi. Also, if we could buy another small tank (or two), this would save much time from re-filling tanks while measuring leaf water potentials (re-filling has to be done at least once, one tank lasts up to 4 trees). Lastly, could we please bring a ladder to the Tonzi Ranch to assist with clipping leaves. |
Field Data
No tank data
No TZ Well data found
No TZ Moisture Point data found
No VR Moisture Point data found
No TZ grass heigth found
No VR grass heigth found
Tree DBH
| Date | Tag# | Reading (mm) |
|---|
No water potential data found
No TZ Grass Biomass data found
No TZ OakLeaves Biomass data found
No TZ PineNeedles Biomass data found
0 photos found
16 sets found
No data found for TZ_Fenergy.
11 TZ_tmet graphs found
No data found for TZ_soilco2.
Can't check TZ_mixed
3 TZ_mixed graphs found
No data found for TZ_fflux.
8 TZ_fmet graphs found
No data found for TZ_tram.
No data found for TZ_co2prof.
No data found for TZ_irt.
No data found for TZ_windprof.
No data found for TZ_tflux.
2 TZ_sm graphs found
Can't check TZ_met
1 TZ_met graphs found
Can't check TZVR_mixed
No data found for TZ_osu.
No data found for TZ_fd.
Tonzi Z-cam data