Respiration in soils collected from the REU synoptic sample grid in the Andrews Experimental Forest, 1994-1995

CO 2 is measured over a period of 41 weeks in soils collected from all of the REU synoptic sample sites in the summer of 1994. Soils were weighted at the same time that respiration was assayed and moisture content was maintained at the same level throughout the series. In the initial stages, CO 2 concentrations were assayed every week, after 15 weeks, the incubation period was extended to 2 weeks. After the incubation vessels were assayed, the headspace was flushed with lab air and the moisture was adjusted with sterile deionized water. This is an extension of the 1994 REU study of the synoptic Andrews sampling grid study reported as SP06. As a part of that study, we conducted respiration rate studies on sieved soils using a 2-week incubation period. We have used this as an indicator of labile carbon in these soils. We wanted to determine how representative this procedure is in determining labile carbon over longer time periods (e.g. will the patterns of relative respiration remain the same) and to determine how long it would take for rates to diminish with time. The time period represented by this data is 15 September 1994 to 12 July 1995. The measurement frequency is weekly during the first 15 weeks of the study and then every two weeks for the balance of the study.