Abstract: A field simulated experiment was conducted to research the effects of nitrogen deposition on the decomposition and nutrient release of leaf litter of Picea schrenkiana. Four treatments were designed,i.e. the CK (contrast,non-addition nitrogen),LN (low nitrogen,5 kg·hm^-2·a^-1),MN (mid nitrogen,10 kg·hm^-2·a^-1) and HN (high nitrogen,15 kg·hm^-2·a^-1). The results are as follows:① After a 24-month decomposition,the residual rate of leaf litter dry weight of P.schrenkiana in CK was 1.04,1.16 and 1.23 times of that in LN,MN and HN respectively,and the difference among the four treatments was significant (P<0.05). The required time for 50% decomposition of leaf litter in CK was 4.58 a,which was 0.46 a,0.75 a and 1.35 a longer than that in LN,MN and HN,and correspondingly,it was 2.01 a,3.24 a and 5.87 a longer for 95% decomposition,respectively. The results revealed that nitrogen deposition promoted the decomposition of leaf litter of P.schrenkiana,especially at latter stage of decomposition. Moreover,the promotion was more obvious with the increase of nitrogen deposition; ② Monthly decomposition rate was in an order of HN>MN>LN>CK. Moreover,the difference among the four treatments was gradually reduced with the time of decomposition; ③ Nitrogen deposition promoted the release of lignin,cellulose and carbon in leaf litter of P.schrenkiana,and increased the accumulated nitrogen,and decreased the C/N.

Key words: nitrogen decomposition, leaf litter decomposition, nutrient release, Picea schrenkiana, mountain forest, arid area