Canopy nitrogen addition enhances fine root decomposition in a temperate forest: implications for soil carbon sink

Fine roots, comprising ~1/3 of terrestrial net primary production, are critical for ecosystem C cycling, yet the influence of atmospheric nitrogen (N) deposition on their decomposition, especially in forests, remains poorly understood. To determine how N deposition via canopy interception affects fine root decomposition, we conducted an eight-year field experiment comparing canopy N addition (CAN) with understory N addition (UAN) at 0, 25, and 50 kg N ha–1 yr–1 in a temperate deciduous forest.