Chinese fir litter decomposition and its response to global change: a metaanalysis across China’s forests

Abstract Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) monoculture plantations account for 17.4% of the total plantation area in China. The decomposition of Chinese fir litter plays a fundamental role in maintaining nutrient cycling and soil fertility in these plantations. Here, we conducted a continental synthesis based on 64 studies to estimate the mass loss and release rates of carbon (C) and nutrients (including nitrogen (N), phosphorous (P), potassium (K), calcium (Ca) and magnesium (Mg)) during the first year of Chinese fir litter decomposition. The average mass loss rates of needle, twig, root and cone litter were 0.503, 0.319, 0.551 and 0.372 year-1, respectively. The decomposition rates of C and cellulose for needle litter were 0.649 and 0.801 year-1, respectively, while those of K, Ca and Mg were 2.27, 0.852 and 0.551 year-1, respectively. Decomposition rates were strongly influenced by mean annual temperature, soil N concentration and the initial C/N ratio of the litter. Climate warming and elevated ultraviolet-B radiation accelerated mass loss of Chinese fir litter, while increased N deposition and acid rain reduced it. However, elevated N deposition facilitated nutrient release from decomposing Chinese fir litter. These results provided a comprehensive assessment of Chinese fir litter decomposition, which is crucial for understanding soil biogeochemical cycles and improving soil fertility in Chinese fir plantations under global change scenarios.