中文摘要：

通过野外模拟试验，研究氮沉降增加对杉木人工林土壤有机碳、全氮及C／N比的影响。试验设计为4种处理，分别为NO（0kg·hm^-2·a^-1）、N1（60kg·hm^-1·a^-1）、N2（120kg·hm^-2·a^-1）、N3（240kg·hm^-2·a^-1），每处理重复3次。以尿素[CO（NH2）2]作为氮源，每月以溶液方式对林地进行喷施。通过2a的处理后发现，随着氮沉降水平的增加，土壤有机碳呈下降趋势，而全氨含量则不断上升，致使土壤C／N比降低。

英文摘要：

A field experiment was set to study effects of increased nitrogen deposition on soil organic carbon, total nitrogen, and C/N ratios in the soils of Chinese fir plantations. Treatments were designed as NO（ 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 ）, with three replicates in each treatment. Urea was used as the source of nitrogen and its solutions were sprayed on the forest ground each month for two years. The results showed that soil organic carbon decreased, but total nitrogen increased with the increasing nitrogen deposition, leading to decreased C/N ratios.