Effects of simulated nitrogen deposition on lignin and cellulose degradation of foliar litter in natural evergreen broad-leaved forest in Rainy Area of Western China.

Abstract

In order to detect the effects of simulated nitrogen deposition on litter decomposition and degradation of lignin and cellulose, a one-year field experiment of simulated nitrogen deposition has been conducted using litter bag method from November 2013 to November 2014 in an evergreen broad-leaved forest, Rainy Area of West China. Four levels of nitrogen deposition were set, i.e., control (0 g N·m-2·a-1), low (5 g N·m-2·a-1), medium (15 g N·m-2·a-1) and high (30 g N·m-2·a-1) nitrogen deposition. The results indicated that foliar litter decomposed faster in summer, obviously faster than in the other seasons. N deposition significantly inhibited the decomposition of foliar litter in this evergreen broad-leaved forest. As N deposition increased, the inhibition effect was enhanced. The time of 95% mass loss (T95%) of foliar litter due to simulated N deposition was increased by 0.53-1.88 years compared with T95% of control (4.81 years). N deposition significantly inhibited the degradation of lignin and cellulose. The mass remaining after one year of decomposition of lignin and cellulose in the medium and high nitrogen deposition treatments were significantly higher than that in the control. There was a significant positive linear relationship among mass remaining rate and lignin and cellulose remaining rates. The inhibiting effects of inorga-nic N on degradation of lignin and cellulose explained the inhibitory effect of N on foliar litter decomposition.