Chin J Plant Ecol ›› 2005, Vol. 29 ›› Issue (4): 543-549.DOI: 10.17521/cjpe.2005.0073

• Research Articles • Previous Articles     Next Articles

EFFECTS OF SIMULATED NITROGEN DEPOSITION ON BIOMASS PRODUCTION AND ALLOCATION IN SCHIMA SUPERBA AND CRYPTOCARYA CONCINNA SEEDLINGS IN SUBTROPICAL CHINA

LI De-Jun1,2,3, MO Jiang-Ming1,*(), FANG Yun-Ting1, LI Zhi-An1   

  1. 1 Dinghushan Forest Ecosystem Research Station, South China Botanical Garden, Chinese Academy of Sciences, Zhaoqing, Guangdong 526070, China
    2 State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
    3 Graduate School of Chinese Academy of Sciences, Beijing 100039, China
  • Received:2004-01-05 Accepted:2004-12-20 Online:2005-01-05 Published:2005-07-31
  • Contact: MO Jiang-Ming
  • About author:* E-mail: mojm@scib.ac.cn

Abstract:

To better understand the effects of elevated nitrogen deposition on biomass production and allocation in seedlings of Schima superba and Cryptocarya concinna, the dominant species in subtropical monsoon evergreen broadleaved forests in China, a simulated nitrogen deposition field experiment was conducted. S. superba and C. concinna seedlings were exposed to five nitrogen treatments 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 nitrogen deposition rates of 0, 5, 10, 15 and 30 g N·m-2·a-1. Each treatment was divided into three subplots and 40 seedlings of each of the two species were transplanted into each subplot. The two species responded differently to the different rates of nitrogen deposition. The stem base diameter, height, whole-plant biomass 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 plot; however, the stem base diameter, height, whole-plant biomass and relative growth rate of treated S. superba seedlings were lower than those in the control plot with the exception of the 10.0 treatment. The leaf-weight ratio of seedlings of the two species was the lowest in the highest treatment, implying that the high N deposition was 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 allocated 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 highest, 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.

Key words: Subtropics, Nitrogen deposition, Tree seedlings, Biomass production, Allocation