Sassafras albidum δ13C root data from trees labeled with 99% 13CO2.

Data showing the number of samples (n) analyzed as well as the average δ13C and associated standard error for each root age class, sampling date, and carbon pool from trees labeled with 99% 13CO2 in 2008 (n = 3) and 2009 (n = 1), where less negative values indicate greater isotopic enrichment. 13CO2 labeling significantly enriched the root structural δ13C in 2008 (n = 35, Pn = 38, P = 0.02). Additionally, both the root starch and root sugars were significantly enriched in 2009 (n = 38, PstarchPsugars = 0.001). The number of days sampling occurred post labeling did not significantly affect enrichment in root structural δ13C in 2008 (P = 0.19) nor root structural δ13C nor root starch δ13C in 2009 (Pstructural = 0.14, Pstarch = 0.26). In 2009 root sugars were significantly affected by the days post labeling (P = 0.005), with roots sampled later showing decreased enrichment. The age of the roots at the time of labeling did not significantly affect enrichment in any of the carbon pools in 2009 (Pstructural = 0.15, Pstarch = 0.26, Psugars = 0.09).