Radiocarbon Measurements at Harvard Forest 1996-2010

Long-term datasets on soil C stocks, radiocarbon content, and CO2 efflux from the Harvard forest, MA were applied to the ForCent model to examine soil C dynamics over long term timescales and under warming and nitrogen amendments. The objective was to determine if manipulations of soil temperature and nitrogen supply affect the relative age of respired soil C substrates. Heating of the soil increased decomposition of all soil C pools, the absolute amount of increased decomposition from the older pools was not large enough to make a difference in 14C composition of respired C from model results. Further the high spatial variation observed in 14C from temperature and nitrogen amendments made it difficult to detect changes in respired C sources over this short a study period.