Nitrogen Deposition and Mycorrhizal Network Disruption Synergistically Accelerate Woody Debris Decomposition

However, their interactive effects on woody debris decomposition remain poorly understood. We conducted a 730-day factorial field experiment in a temperate Korean pine mixed forest in northeastern China, combining N addition (50 kg N·ha-1·a-1) and root trenching to investigate their individual and synergistic effects on wood decomposition and fungal community dynamics.

Nitrogen addition significantly increased mass loss (15.97%) and carbon loss (15.17%) from birch wood while suppressing phosphorus enrichment (26.46%), indicating a stoichiometric shift in nutrient limitation. Root trenching exhibited context-dependent effects: under ambient N conditions, it initially inhibited decomposition at 365 days but promoted it at 730 days, challenging the universality of the Gadgil effect. However, under N-enriched conditions, trenching consistently accelerated decomposition, particularly in later stages, suggesting synergistic interaction between N availability and mycorrhizal disruption.