Intrinsic nutrients and defensive compounds drive coarse woody debris decay in five dominant subtropical tree species, China

Coarse woody debris (CWD) is crucial for carbon and nutrient cycling in forest ecosystems, with decomposition rates influenced by species-specific wood traits. This five-year study in a subtropical Chinese forest evaluated the CWD decomposition of five dominant species. Results showed that broadleaved species decomposed fastest (k = 0.230 years^-1), followed by moso bamboo (0.168 years^-1), and conifers slowest (0.022 years^-1). Fast-decaying species were characterized by high hemicellulose, cellulose, and phosphorus (P) content, with rapid P release within the first decay year and nitrogen (N) accumulation over time. Tannin initially inhibited decay in fast-decaying species, but defensive compounds (tannins and phenolics) showed no sustained effect on decomposition rates. These findings indicate active CWD decomposition in subtropical forests, where P limitation outweighs N for broadleaves and bamboo. Defensive compounds only weakly influenced early-stage decay. Our results enhance the understanding of deadwood decomposition and carbon sink dynamics in subtropical ecosystems.