Potential contributions of root decomposition to the nitrogen cycle in arctic forest and tundra

1. Plant contributions to the nitrogen (N) cycle from decomposition are likely to be altered by vegetation shifts associated with climate change. Roots account for the majority of soil organic matter input from vegetation, but little is known about differences between vegetation types in their root contributions to nutrient cycling. Here, we examine the potential contribution of fine roots to the N cycle in forest and tundra to gain insight into belowground consequences of the widely-observed increase in woody vegetation that accompanies climate change in the Arctic. 2. We combined measurements of root production from minirhizotron images with tissue analysis of roots from differing root diameter and colour classes to obtain potential N input following decomposition. In addition, we tested for changes in N concentration of roots during early stages of decomposition, and investigated whether vegetation type (forest or tundra) affected changes in tissue N concentration during decompositio...1. 气候变化所引发的植被更替，可能会改变植物残体分解对氮（N）循环的贡献。植被向土壤输入的有机质中，根系占比最高，但目前对不同植被类型的根系在养分循环中的贡献差异仍知之甚少。本研究以森林与苔原生态系统的细根为研究对象，探究其对氮循环的潜在贡献，以期深入理解北极地区伴随气候变化出现的木本植被广泛扩张所带来的地下生态后果。 2. 我们将微根管（minirhizotron）图像测得的根系生产力数据，与不同直径、颜色分级的根系组织分析结果相结合，以获取分解后潜在的氮输入量。此外，我们还检测了分解初期根系的氮浓度变化，并探究植被类型（森林或苔原）是否会影响分解过程中组织氮浓度的改变……