中文摘要：

通过野外模拟试验,研究了杉木人工林（Cunninghamia lanceolata）凋落物养分归还对氮沉降增加的响应。试验设计为4种处理,分N0（对照）、N1、N2、N3共4种处理,N沉降量分别为0,60,120,240kg N/（hm2.a）。每处理重复3次。通过3a监测发现,经N0、N1、N2、N3处理,N元素平均年归还量分别为8.49,8.51,9.57,9.37kg/hm2,P分别为0.74,0.68,0.73,0.72kg/hm2,K分别为3.57,3.93,4.02,3.98kg/hm2,Ca分别为6.81,6.96,6.76,7.12kg/hm2,Mg分别为2.12,2.22,2.08,2.30kg/hm2,相对于N0处理,各水平的氮沉降处理在3a时间里表现为提高凋落物N归还量的作用,但是增长幅度有下降的趋势,对P元素归还有抑制作用,对K、Ca、Mg元素先期表现为促进其归还量的作用,但在后期逐渐有呈抑制的趋势。各处理凋落物5种元素归还量均在2,4,7月出现3个明显的归还高峰期,最大值均出现在7月份。

英文摘要：

A field experiment was conducted to study the effect of simulated nitrogen on nutrient flux of litterfall in a Chinese fir plantation.Urea（CO（NH2）2） was added at three doses,N1,N2 and N3,60,120,240 kg N/（hm2·a）,respectively.Based on litterfall collection during 3 years,through litterfall production,the annual N flux to the forest floor under the four treatments（N0,N1,N2 and N3） was estimated,respectively,at 8.49,8.51,9.57,9.37 kg/hm2;P at 0.74,0.68,0.73,0.72 kg/hm2;K at 3.57,3.93,4.02,3.98 kg/hm2;Ca at 6.81,6.96,6.76,7.12 kg/hm2;Mg at 2.12,2.22,2.08,2.30 kg/hm2.The data suggested that the annual flux of N elements responded positively to N1,N2 and N3 treatments,compared with the control（N0）,but growth rate decreased with the increasing N additions,negatively to P flux.It showed increased flux of K,Ca,and Mg for N1,N2 and N3 treatments firstly,thereafter decreased with the time passing by.The macronutrient flux through litterfall exhibited three pronounced peaks,occurring consistently in February,April and July respectively,maximum occurred in July.