Effects of Enhanced UV-B Radiation on Decomposition and Nutrient Release Rates of Litter from Cunninghamia lanceolata (Lamb.) Hook

In order to explore the effects of enhanced UV-B radiation on the decomposition and nutrient cycling characteristics of Cunninghamia lanceolata (Lamb.) Hook litter, we collected material from C. lanceolata in a middle-aged forest (16 years) and over-mature forest (49 years). Four different UV-B radiation enhancement gradient treatments of CK, CK + 30 uw/cm2 (T1), CK + 45 uw/cm2 (T2), and CK + 60 uw/cm2 (T3), with natural light (CK) as the baseline, were conducted to determine the impact of UV-B radiation indoor simulation enhancement on the litter decomposition and nutrient release of C. lanceolata at various developmental stages. The results indicate that UV-B radiation increases the dry weight decomposition rate and the nutrient decomposition rate of C. lanceolata litter, and the decomposition rate of C. lanceolata litter in an over-mature forest is always greater than that in a middle-aged forest litter, with observable influences on its chemical composition. Such changes significantly alter the nutrient release pattern of N, P, and K in litter in middle-aged forests and N in litter from over-mature forests, and promote the release of C, which may affect the nutrient cycle and carbon sink function of C. lanceolata plantations.