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Pedosphere 17(5): 660--665, 2007
ISSN 1002-0160/CN 32-1315/P
©2007 Soil Science Society of China
Published by Elsevier B.V. and Science Press

Soil and root respiration under elevated CO₂ concentrations during seedling growth of Pinus sylvestris var. sylvestriformis

LIU Ying

^1,2, HAN Shi-Jie

², ZHOU Yu-Mei² and LI Xue-Feng²

¹ College of Resource Science and Papermaking Engineering, South China University of Technology, Guangzhou 510640 (China). E-mail: liuyingamy@163.com;
² Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016 (China)

ABSTRACT

The objectives of this study were to investigate the effect of higher CO₂ concentrations (500 and 700μmol mol^-1) in atmosphere on total soil respiration and the contribution of root respiration to total soil respiration during seedling growth of Pinus sylvestris var. sylvestriformis. During the four growing seasons (May-October) from 1999 to 2003, the seedlings were exposed to elevated concentrations of CO₂ in open-top chambers. The total soil respiration and contribution of root respiration were measured using an LI-6400-09 soil CO₂ flux chamber on June 15 and October 8, 2003. To separate root respiration from total soil respiration, three PVC cylinders were inserted approximately 30 cm deep into the soil in each chamber. There were marked diurnal changes in air and soil temperatures on June 15.Both the total soil respiration and the soil respiration without roots showed a strong diurnal pattern, increasing from before sunrise to about 14:00 in the afternoon and then decreasing before the next sunrise. No increase in the mean total soil respiration and mean soil respiration with roots severed was observed under the elevated CO₂ treatments on June 15, 2003, as compared to the open field and control chamber with ambient CO₂. However, on October 8, 2003, the total soil respiration and soil respiration with roots severed in the open field were lower than those in the control and elevated CO₂ chambers. The mean contribution of root respiration measured on June 15, 2003, ranged from 8.3% to 30.5% and on October 8, 2003, from 20.6% to 48.6%.

Key Words: contribution of root respiration, elevated CO2 concentration, total soil respiration

Citation: Liu, Y., Han, S. J., Zhou, Y. M. and Li, X. F. 2007. Soil and root respiration under elevated CO₂ concentrations during seedling growth of Pinus sylvestris var. sylvestriformis. Pedosphere. 17(5): 660-665.

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