探讨了南亚热带季风常绿阔叶林两种优势树种荷木（Schima superba）和黄果厚壳桂（Cryptocarya concinna）幼苗的生物量及其分配对氮沉降增加的响应。实验分为对照（CK）、T5、T10、T15和T30 5个处理，每个处理设置3次重复。所施氮肥为NH4NO3，以溶液方式喷施，5个处理浓度分别为0、0.12、0.24、0.36、0.72 mol N·L-1。每月喷施2次，5个样方1年喷施的总氮量分别相当于氮沉降率0、5、10、15、30 g N·m-2·a-1。经过11个月的施氮处理，两种幼苗对氮沉降的响应存在差异，其中黄果厚壳桂幼苗的基径、株高、全株生物量和相对生长速率除最高处理T30外，均高于对照，但荷木幼苗的基径、全株生物量和相对生长速率除T10外，均小于对照。氮处理也对生物量的分配产生了明显的影响，两种幼苗的叶重比以T30最低，表明高氮处理不利于幼苗叶片的生长；枝重比均以T30最高，反映了高氮处理的幼苗生物量分配到枝干的比例最高；根重比和根冠比均以对照样方幼苗的最高，表明氮处理抑制根的生长，分配到根部分的生物量下降。总的来看，经过11个月的处理，除最高处理T30外，氮处理仍对黄果厚壳桂幼苗的生长有促进作用，而对荷木幼苗的生长则趋向于一定程度的抑制效应，表明黄果厚壳桂幼苗更能耐受高氮条件。
To better understand the effects of elevated nitrogen deposition on bio mass production and allocation in seedlings of Schima superba and Cryptoca rya concinna,the dominant species in subtropical monsoon evergreen broadleave d forest s in China, a simulated nitrogen deposition field experiment was conducted. S. superba and C. concinna seedlings were exposed to five nitrogen treat ments using NH4NO3 solutions of 0,0.12,0.24,0.36 and 0.72 mol N· L-1. Solutions were applied twice a month from January through November, 2003, equivalent to nitroge n deposition rates of 0, 5, 10, 15 and 30 g N·m-2·a-1. Each treatment was div ided into three subplots and 40 seedlings of each of the two species were transp lanted into each subplot. The two species responded differently to the different rates of nitrogen deposition. The stem base diameter, height, whole-plant bioma ss and relative growth rate of C. concinna seedlings grown in 5, 10, 15 g N ·m-2·a-1 treatments were all higher than those in the control plo t; however, the s tem base diameter, height, whole-plant biomass and relative growth rate of treat ed S. superba seedlings were lower than those in the control plot with the e xcep tion of the 10.0 treatment. The leaf-weight ratio of seedlings of the two specie s was the lowest in the highest treatment, implying that the high N deposition wa s harmful to the foliage. The branch-and-stem weight ratio of seedlings of both species was the highest in the highest treatment indicating that the biomass all ocated to branches and stems increased under high N deposition. The root-weight ratio and the root to shoot ratio of seedlings in the control plots were the hig hest, demonstrating that the ratio of biomass allocated to roots decreased under the conditions of elevated nitrogen deposition. Overall, except for the highest N treatment, nitrogen additions enhanced the growth of C. concinna but had the opposite effect on S. superba individuals, indicating that C. concinna seedlings were more resistant to high nitrogen loads.