Chin J Plant Ecol ›› 2008, Vol. 32 ›› Issue (4): 908-913.DOI: 10.3773/j.issn.1005-264x.2008.04.020

• Original article • Previous Articles     Next Articles

EFFECT OF RANGE FIRE ON NITROGEN FIXATION OF COLLEMA TENAX IN A SEMIARID GRASSLAND OF INNER MONGOLIA, CHINA

WU Qing-Feng1,2, LIU Hua-Jie1,3,*()   

  1. 1College of Life Sciences, Hebei University, Baoding, Hebei 071002, China
    2Hebei Laboratory of Research and Application on Microbial Diversity, Baoding, Hebei 071002, China
    3State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
  • Received:2007-09-25 Accepted:2008-01-30 Online:2008-09-25 Published:2008-07-30
  • Contact: LIU Hua-Jie

Abstract:

Aims Collema tenax is a common N-fixing lichen in arid and semiarid grasslands, where range fire can be an important factor influencing ecosystem structure and function. The response of N-fixing activity of lichens to range fire has received little attention in ecological studies. Our purpose was to investigate the short-term effects of range fire on N fixation of C. tenax.

Methods Three months after a controlled burn at the Inner Mongolian semiarid grassland, we measured plant cover, litter cover and N-fixing activity of C. tenax in both burned plots and control plots. N-fixing activity was measured using acetylene reduction assay. One-Way ANOVA was applied to compare N-fixing activity between treatments.

Important findings At the individual scale, N-fixing activity of C. tenax decreased by 42.3% for individuals with a burned thallus, but increased by 28.4% for those with an intact one, as compared to that observed in unburned plots. These results show counteractive effects of burning on N fixation of C. tenax at individual scale, i.e., 1) negative effect through damage on lichen thallus and potential deterioration in surface water and temperature conditions and 2) positive effect as a result of increased light availability via removal of litter and plant biomass and, to a lesser extent, a fire-induced nutrient pulse on the soil surface. At the population scale, no significant effects of burning on N-fixing activity of this lichen were found, which may be attributable to the counteractive responses of N fixation of C. tenax at the individual scale.

Key words: grassland ecosystem, controlled burning, lichen, N fixation, acetylene reduction assay