Chin J Plant Ecol ›› 2013, Vol. 37 ›› Issue (6): 530-541.DOI: 10.3724/SP.J.1258.2013.00054

• Research Articles • Previous Articles     Next Articles

Responses of photosynthetic characteristics of Stipa baicalensis to grazing disturbance

YAN Xin,GONG Ji-Rui(),ZHANG Zi-Yu,HUANG Yong-Mei,AN Ran,QI Yu,LIU Min   

  1. State Key Laboratory of Surface Processes and Resource Ecology, College of Resources Science and Technology, Beijing Normal University, Beijing 100875, China
  • Received:2012-11-13 Accepted:2013-02-09 Online:2013-11-13 Published:2013-06-05
  • Contact: GONG Ji-Rui


Aims Our objective was to evaluate (a) the impact of livestock grazing disturbance on physiological traits of Stipa baicalensis and (b) the adaptive mechanisms that S. baicalensis employed.
Methods We investigated the diurnal variations of photosynthetic characteristics, water relations, light energy utilization, photosynthetic apparatus activity and osmotic regulation of S. baicalensis growing in both grazing and enclosed grassland of Hulun Buir, Inner Mongolia.
Important findings Both ribulose-1,5-bisphosphate carboxylase (RUBPCase) and chlorophyll content increased and the direction of electronic chain was altered with grazing, which is beneficial for S. baicalensis to cope with the impact of grazing disturbance by accumulating more assimilates. The midday depression of photosynthesis of S. baicalensis in the enclosed grassland resulted from the decline of RUBPCase carboxylation capacity, which is due to the absence of P. The photochemical quenching (qP) of S. baicalensis in the grazed grassland is higher, which reflects that it tended to use more absorbed solar energy to improve photosynthetic capacity, which was adaptive to the effects of grazing. Lower leaf water content of S. baicalensis in the grazed field led to the increase of osmotic regulating substances for obtaining sufficient water from the soil. In addition, grazing disturbance promoted the absorption and utilization of N by S. baicalensis. Negative correlation of leaf mass per area (LAM) with photosynthetic nitrogen-use efficiency (PNUE) and photosynthetic phosphorus-use efficiency (PPNE) was observed in the S. baicalensis in both grasslands. Our research demonstrated that various ecophysiological mechanisms were employed by S. baicalensis as adaptive to grazing.

Key words: fluorescence characteristics, grazing disturbance, photosynthetic characteristics, Stipa baicalensis, water relation