The article "Reduction of forest soil respiration in response to nitrogen deposition" by I. A. Janssens et al. examines the impact of increased atmospheric nitrogen deposition on forest soil respiration and carbon cycling. The study highlights that while nitrogen deposition has generally been shown to stimulate plant growth and carbon sequestration in temperate forests, it also reduces soil microbial activity and organic matter decomposition, leading to a decrease in heterotrophic respiration and soil carbon dioxide efflux (SCE). The meta-analysis of 36 nitrogen manipulation studies reveals a significant decline in heterotrophic respiration (15%) and SCE (-17%) in forests exposed to elevated nitrogen deposition. The reduction in soil respiration is attributed to decreased microbial biomass and altered microbial community structure, particularly in young forests and under elevated CO2 conditions. The study emphasizes the need to incorporate nitrogen cycling and deposition into terrestrial carbon-cycle models to better understand and predict the long-term effects of nitrogen deposition on forest ecosystems.The article "Reduction of forest soil respiration in response to nitrogen deposition" by I. A. Janssens et al. examines the impact of increased atmospheric nitrogen deposition on forest soil respiration and carbon cycling. The study highlights that while nitrogen deposition has generally been shown to stimulate plant growth and carbon sequestration in temperate forests, it also reduces soil microbial activity and organic matter decomposition, leading to a decrease in heterotrophic respiration and soil carbon dioxide efflux (SCE). The meta-analysis of 36 nitrogen manipulation studies reveals a significant decline in heterotrophic respiration (15%) and SCE (-17%) in forests exposed to elevated nitrogen deposition. The reduction in soil respiration is attributed to decreased microbial biomass and altered microbial community structure, particularly in young forests and under elevated CO2 conditions. The study emphasizes the need to incorporate nitrogen cycling and deposition into terrestrial carbon-cycle models to better understand and predict the long-term effects of nitrogen deposition on forest ecosystems.