关键词: 氮沉降, 杉木人工林, 凋落物

Abstract: A field simulated experiment was conducted in a Chinese fir plantation to study the effects of nitrogen deposition on the literfall production. Treatments were designed as N0 (0 kg·hm^-2·a^-1), N1 (60 kg·hm^-2·a^-1), N2 (120 kg·hm^-2·a^-1) and N3 (240 kg·hm^-2·a^-1). According to three years’ collection, the annual litterfall production for the four treatments was estimated, respectively, at 2 427.50, 2 238.10, 2 286.66 and 2 599.50 kg·hm^-2in the year 2005, 1 008.83, 1 164.10, 1 147.30 and 976.47 kg·hm-2 in 2006, 1 557.85, 1 445.60, 1 595.85 and 1 555.85 kg·hm^-2 in 2007, suggesting that litterfall production firstly showed a decline then an increase. Compared with N0, N3 treatment increased the litterfall production significantly in 2005, but showed some inhibitive effects in the following years. N2 treatment promoted litterfall production after the first year, but N1 had no consistent effects.. The various components of litterfall revealed different response to nitrogen deposition, with the annual flux for leaffall responding positively to N2 treatments but negatively to N1 and N3. The treatments decreased the litterfall amount for braches and barks but increased the fractions of fruits and miscellancous materials.

Key words: nitrogen deposition, Chinese fir plantation, litterfall