[Responses of litter decomposition in two subalpine plantations to simulated nitrogen deposition in central Yunnan, China].

From February 2018 to January 2019, a field experiment of simulated nitrogen (N) depo-sition was conducted in and plantations in the subalpine region of central Yunnan, China. The litterbag method was used for litter (leaf and twig) decomposition experiment in both plantations. Four levels of N addition were applied, ., control (CK, 0 g N·m·a), low nitrogen (LN, 5 g N·m·a), medium nitrogen (MN, 15 g N·m·a), and high nitrogen (HN, 30 g N·m·a). The results showed that the annual decomposition rates of leaf and twig in were 34.8% and 18.0%, which were higher than the 32.2% (leaf) and 16.1% (twig) in Under N deposition, the LN treatment reduced the time of 95% mass loss of leaf and twig litter in by 0.202 and 1.624 years, the MN treatment reduced by 0.045 and 1.437 years, and the HN treatment increased by 0.840 and 2.112 years, respectively. In the plantation, the LN treatment reduced the time of 95% mass loss of leaf and twig litter by 0.766 and 4.053 years, while the MN treatment increased by 0.366 and 0.455 years, and the HN treatment increased by 0.826 and 0.906 years, respectively. Litter (leaf and twig) decomposition of both and were promoted by low N treatment and inhibited by high N treatment. The effects of N deposition on litter decomposition of two plantations were significantly correlated with the contents of cellulose and lignin in litter. In conclusion, the responses of litter decomposition to N deposition mainly depended on the litter substrate, especially cellulose and lignin contents.