Canopy and understory nitrogen addition have different effects on fine root dynamics in a temperate forest: implications for soil carbon storage
Canopy and understory nitrogen addition have different effects on fine root dynamics in a temperate forest: implications for soil carbon storage
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冠层和林下氮添加对温带森林细根动态有不同的影响：对土壤碳储存的影响
DOI：
10.1111/nph.17460
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发表时间：
2021-06-12
期刊：
影响因子：
9.4
通讯作者：
Fu, Shenglei
中科院分区：
文献类型：
--
作者：
Li, Xiaowei;Zhang, Chenlu;Fu, Shenglei
阐明大气氮（N）沉降对细根动态的影响及潜在的作用机制，对于理解地下和地上碳储量的变化至关重要。然而，森林中关于这些影响的研究大多是直接在林下添加氮，而忽略了树冠对氮的截留和处理。在此，我们开展了一项田间实验，对比了在温带落叶林中，以三种施氮速率（0、25和50千克氮·公顷⁻¹·年⁻¹）进行树冠施氮（CAN）和林下施氮（UAN）对细根动态的影响。与林下施氮相比，树冠施氮下细根的生产量和生物量显著更高。在相同的施氮速率下，树冠施氮使细根生产量的增加幅度至少是林下施氮的两倍。在高施氮速率下，与对照相比，树冠施氮使细根生物量显著增加（增加23.5%），而林下施氮则使细根生物量显著减少（减少12.2%）。我们的研究结果表明，传统的林下施氮方式可能低估了森林生态系统中细根动态对大气氮沉降的响应。为了更真实地评估大气氮沉降对森林的影响，应考虑树冠的氮处理过程。
Elucidating the effects of atmospheric nitrogen (N) deposition on fine root dynamics and the potential underlying mechanisms is required to understand the changes in belowground and aboveground carbon storage. However, research on these effects in forests has mostly involved direct understory addition of N and has ignored canopy interception and processing of N.Here, we conducted a field experiment comparing the effects of canopy addition of N (CAN) with those of 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 two-fold greater than with UAN. At the high N-addition rate and relative to the control, fine root biomass was significantly increased by CAN (by 23.5%) but was significantly decreased by UAN (by 12.2%).Our results indicate that traditional UAN may underestimate the responses of fine root dynamics to atmospheric N deposition in forest ecosystems. Canopy N processes should be considered for more realistic assessments of the effects of atmospheric N deposition in forests.