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.本研究开展了一项田间试验，对比了冠层施氮（Canopy Addition of N, CAN）与林下施氮（Understory Addition of N, UAN）在三种施氮梯度（0、25和50 kg N ha⁻¹ yr⁻¹）下对温带落叶林细根动态的影响。冠层施氮处理下的细根生产量与生物量均显著高于林下施氮处理。在相同施氮梯度下，冠层施氮对细根生产量的提升幅度至少为林下施氮的2倍。在高施氮梯度下，相较于对照组，冠层施氮使细根生物量显著提升23.5%，而林下施氮则使其显著降低12.2%。