Responses Of The Chinese Fir Plantation Litter And Its Decomposition Course To Simulated N Deposition

Cunning hamia lanceolata (lamb.) Hook is a kind of important timber tree. Chinese fir plantation is a quarter of area in total artificial forest. With constructions increasing, the Chinese fir plantation increases than before. In nature the N deposition is mainly inputting in forest system. Nitrogen deposition researches mostly in European and North America's temperate zone forest regions, little comes from the tropics and the subtropics regions. This experiment locates in sub-tropic regions, the study offer the theory base of sustainable development.The subject is Chinese fir plantation, trough the manual simulation nitrogen deposition (N0, N1, N2, N3) to understand the effects of nitrogen deposition on forest litter and its decomposition process. The results show:[1.] The effect variety of nitrogen deposition on litter-fall dynamics is small. The total of litter and leaf litter have the same peak in February, May, July, September in different treatments, All display the leaf >branch >debris. The total litter of N0, N1, N2, N3 are 27.50 kg.hm^-2, 2238.17 kg.hm^-2, 2287.94 kg.hm^-2 and 2429.50 kg.hm^-2, respectively, the order is N3>N0>N2>N1 and in all dealings the different is not significant. The leaf range of variation is 1577.70～1788.07 kg.hm^-2, the branch range variation is 434.30～484.30 kg.hm^-2, The skin variation range is 7.30～8.57 kg.hm^-2, the fruit variation range is 26.87～556.07 kg.hm^-2, the debris range variation is 120.80～172.23 kg. hm^-2. The leaf and branch hold the absolute content. The range from 68.86 to 73.66%.[2.] N3 is 1.82 g.kg^-1 heavier than the N0 processing in average leave litter. The leave's N content increasing with N deposition. P content different greatly in 1-3 month among difference dealings. The P content in N0 processing is much less than other processing, but not significant. The N dealing has little effect on Ca content, but can increase the Mg content.[3.] Total litter nutrition returns: N0 is 21.87kg.hm^-2, N1 is 22.48 kg.hm^-2, N2 is 23.22 kg.hm^-2 and N3 is 26.88 kg.hm^-2, the order is N3>N2>N1>N0, which increases with the processing level increasing.[4.] The time of decomposing 50% and 95% litter is no different. The t_0.5 variety range is 4.2813～5.165 a; t_0.95 rang is 18.5036～22.3229a.