Background/Question/Methods N deposition induces a complex series of alterations to soil and plant chemistry that affect productivity, competition, and microbial community structure in forest ecosystems. Fine roots are the direct interface between plant and soil nutrient pools; root production and turnover affects the amount of N uptake and C released to the atmosphere. Effects of N deposition on fine-root standing crop and turnover rates differ depending on edaphic conditions and duration of N deposition. To help unravel the various pathways by which N deposition affects root standing crop and turnover, we are examining root production and mortality, root allocation and root physiology. Here we summarize reports on the effects of N deposition on lifespan and standing crop across 12 studies. We also examined root N concentration, root electrolyte leakage and root oxidative stress at four long-term N fertilization sites in the northeastern U.S. and in China. Results/Conclusions Long-term whole-plot level N fertilization for 3-28 years generally decreases fine-root biomass standing crop across a wide range of site characteristics and forest types in Europe, China and N. America. Decreases in root standing crop could be a result of reduced root production or increased root mortality or both. Fine-root turnover determination is more complex due to methodological limitations. Results of minirhizotron studies indicate that fine-root turnover under whole-plot N fertilization does not necessarily increase with N addition. Different levels of root stress with N addition might be a possible explanation for the variation in root mortality response. Indicators of root oxidative stress and electrolyte leakage tended to be greater in N-fertilized plots for sites with more acidic soil, but not for sites with more buffered soil. The implications of these results will be discussed.