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...