Field Notes

Trip note On Sep. 18, 2003 (d261)
Who: Jianwu Tang, with Ted Hehn
Weather: clear

I measured soil CO2 efflux along the transect and checked and downloaded the soil CO2 profile measurements, and measured tree respiration. CO2 24cm sensor in the open areas was installed.

CO2 efflux averaged 0.7 mmol m^-2 s^-1 under trees, while 0.3 mmol m^-2 s^-1 in the open areas.

At 9:30 am I watered two small plots, one mimicking 10mm rain and the other 5mm rain. Soil respiration immediately increased from 0.17 to as high as 20 mmol m^-2 s^-1, and then gradually declined. Soil respiration after watering dropped to 5.2 mmol m^-2 s^-1 for the 10mm-rain plot and 3 mmol m^-2 s^-1 for the 5mm-rain plot. More measurements are needed.

On Sep. 23 after the Kearney workshop I went to the site again to check the watered plot, Soil respiration was 0.8 mmol m^-2 s^-1 or the 10mm-rain plot, and 0.2 mmol m^-2 s^-1 for the 5mm-rain plot.

Soil moisture probe reading: