Humans are putting large amount of reactive nitrogen (N) into the Earth system, and understanding how these extra N inputs affect forest growth is an important and poorly-understood problem. In this study Wang et al. use a fertilization experiment to examine how extra N changes the structure and function of fine roots in a managed Korean pine forest. Such roots are difficult to observe but critical to forest growth and carbon dynamics. They observed strong increases in fine root turnover and biomass, implying a stimulation of the entire belowground carbon cycle. These results have implications for modeling and our understanding of how forests will respond to increased nutrient availability.
