Chin J Plant Ecol ›› 2006, Vol. 30 ›› Issue (1): 90-96.DOI: 10.17521/cjpe.2006.0013

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NITRIFICATION AND DENITRIFICATION IN SUBALPINE CONIFEROUS FORESTS OF DIFFERENT RESTORATION STAGES IN WESTERN SICHUAN, CHINA

LIU Yi CHEN, CHEN Jin-Song, LIU Qing*(), WU Yan   

  1. Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
  • Received:2004-07-29 Accepted:2005-05-19 Online:2006-07-29 Published:2006-01-30
  • Contact: LIU Qing

Abstract:

Nitrification is biological conversion of organic or inorganic nitrogen compounds from a reduced a more oxidized state. Denitrification is generally referred as the microbial reduction of nitrate to nitrite and further gaseous forms of nitric oxide, nitrous oxide and molecular nitrogen. They are functionally interconnected processes in the soil nitrogen cycle that are involved in the control of long-term nitrogen losses in ecosystems through nitrate leaching and gaseous N losses. In order to better understand how nitrification and denitrification change during the process of ecosystem restoration and how they are affected by various controlling factors, gross nitrification rates and denitrification rates were determined using the barometric process separation (BaPS) technique in subalpine coniferous forests of different restoration stages. The results showed that the forest restoration stage had no significant effect on gross nitrification and denitrification rates (One-way ANOVA, p<0.05). There were no significant differences in the temperature coefficient (Q10) for gross nitrification rate among all forest types (One-way ANOVA, p<0.05). Gross nitrification rates were positively related to water content (p<0.05) but not to soil pH, organic matter, total nitrogen, or C/N ratios. Denitrification rates in all forest soils were low and not closely related to the water content, the pH value, organic matter, or total nitrogen. Nevertheless, we found that C/N ratios obviously affected denitrification rates (p<0.05). Results from this research suggest that gross nitrification is more responsible for the nitrogen loss from soils as compared with denitrification.

Key words: Gross nitrification, Denitrification, Barometric process separation (BaPS), Subalpine coniferous forest