Canopy and understory nitrogen addition have different effects on fine root dynamics in a temperate forest: implications for soil carbon storage

Here, we conducted a field experiment comparing the effects of canopy addition of N (CAN) with understory addition of N (UAN) at three N-addition rates (0, 25, and 50 kg N ha^–1 yr^–1) on fine root dynamics in a temperate deciduous forest. Fine root production and biomass were significantly higher with CAN than with UAN. At the same N-addition rate, increases in fine root production with CAN were at least 2-times greater than with UAN. At the high N-addition rate and relative to the Control, fine root biomass was significantly increased by 23.5% by CAN but was significantly decreased by 12.2% by UAN.