The BOREAS TGB-12 team made measurements of soil carbon inventories, carbon concentration in soil gases, and rates of soil respiration at several sites to estimate the rates of carbon accumulation and turnover in each of the major vegetation types. Sampling strategies for soils were designed to take advantage of local fire chronosequences, so that the accumulation of C in regrowing mosses could be determined. All the data are used to (1) calculate the inventory of C and N in moss and mineral soil layers at NSA sites (2) determine the rates of input and turnover (using both accumulation since the last stand-killing fire and radiocarbon data) and (3) link changes in soil respiration rate to shifts in the 14C content of soil CO2 to determine the average 'age' respired CO2. These 222Rn activity data were collected from 15-NOV-1993 to 16-AUG-1994 over the NSA sites.