Root production
In contrast to the patterns observed with root-derived C inputs, root
production was strongly predicted by site and (to a lesser extent) ECM
dominance, with a significant site × ECM dominance interaction
(R2 = 0.72, P < 0.001).
Comparing the end-member plots only, root production varied
significantly both by plot mycorrhizal type (F1,24= 4.66, P = 0.041) and among sites (F5,24 =
15.19, P < 0.001; Fig. 2b). Overall, root production was
greater in ECM-dominated plots compared to AM-dominated plots. The
highest root production was observed in ECM plots at HF (107 ± 8.94 g C
m-2 yr-1) while the lowest root
production was observed in ECM plots at SCBI (16.4 ± 1.13 g C
m-2 yr-1). While there were no
significant pairwise differences between plot mycorrhizal types within a
given site, mean root production values were higher in ECM compared to
AM plots at four of the six sites: HF, LDW, SERC, and TRC.