Chin J Plant Ecol ›› 2009, Vol. 33 ›› Issue (4): 728-738.DOI: 10.3773/j.issn.1005-264x.2009.04.011

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TU Li-Hua, HU Ting-Xing*(), HUANG Li-Hua, LI Ren-Hong, DAI Hong-Zhong, LUO Shou-Hua, XIANG Yuan-Bin   

  1. Key Laboratory of Ecological Forestry Engineering of Sichuan Province, College of Forestry, Sichuan Agricultural University, Ya’an, Sichuan 625014, China
  • Received:2009-01-07 Revised:2009-03-25 Online:2009-01-07 Published:2009-07-30
  • Contact: HU Ting-Xing


Aims Our objectives were to determine the effect of increased nitrogen deposition on total soil respiration and microbial respiration of Pleioblastus amarus forest, and whether increased nitrogen deposition alters the temperature sensitivity of soil respiration.
Methods For one year starting November 2007, we conducted a simulated nitrogen deposition field experiment in P. amarus forest, Rainy Area of West China. The levels of nitrogen deposition were control (CK, 0 g N·m-2·a-1), low nitrogen (5 g N·m-2·a-1), medium nitrogen (15 g N·m-2·a-1) and high nitrogen (30 g N·m-2·a-1). At the end of each month, soil respiration was measured by infrared gas analyzer, and NH4NO3 was added to N-treated plots. Natural wet nitrogen deposition was measured in 2008, and 0-20 cm horizon soil was collected for soil respiration sampling in November 2008. These soil samples were maintained in the laboratory at 20 ℃, and we measured soil microbial respiration (by infrared gas analyzer) and microbial biomass carbon and nitrogen.
Important findings The wet nitrogen deposition of Liujiang, Hongya County is 8.241 g·m-2; it exceeds the local nitrogen deposition critical loads. Root respiration accounts for about 60% of the total soil respiration of P. amarus forest from April to October. Nitrogen deposition promotes soil respiration of P. amarus forest, and CO2 release from forest soil is increased by 9.4%-28.6%. Microbial respiration, microbial biomass carbon and nitrogen were stimulated by nitrogen deposition, and respiration rate rises with increased nitrogen deposition. The soil respiration rate exhibited positive exponential relation- ships with air temperature and soil temperature at 10 cm depth. Exponential relationships between temperature and soil respiration were highly significant in all plots. Nitrogen deposition may increase temperature sensitivity of soil respiration. With increasing rates of anthropogenic N deposition and global warming, nitrogen combined with temperature may increase the release of CO2 from P. amarus forest soil.

Key words: nitrogen deposition, soil respiration, root respiration, microbial respiration, temperature sensitivity, Pleioblastus amarus forest, Rainy Area of West China