On July 14-15, 1993, CO2 evolution rates were measured using soda lime jars in the same chamber that have been used for the gas-flux experiments. Sites were located approximately 0.5 km apart along HJA roads. Locations were fixed by their location relative to road intersections and clearcuts. Approximately every 10 sites, we put out a control to compensate for background CO2 concentrations and CO2 adsorbed during the drying process.
Predried and weighed jars were used in this experiment. After the jars were exposed to the atmosphere, they were dried and weighed at the HJA. The control jars were taken at approximately the same elevation and in the same vegetation type as the actual samples whenever possible. Soil and air temperatures were recorded when the jars were placed out and when they were retrieved (usually 24 hours later). Max-min thermometers were placed at each site where the controls were run, and recorded 24-hour max and min air temperatures. Soil cores were taken to a depth of 10 cm and dried at 100°C for 12 hours. The major vegetation at each site was also noted and a desription of those sites are also listed in the site description dataset. The positions of the sites were estimated by tracing distances along roads using a map generated by Hazel Hammond and the discriptive logs were made in the field.
Soil respiration values have been corrected for background CO2 and CO2 adsorbed in the drying process using the mean of the control weight differences for each of the two transects.
