Fig. 4

Effects of grazing intensity on activities of nitrogen assimilation related enzymes in roots and leaves of Stipa breviflora. a and c glutamate synthase activity (µmol g^− 1 min^− 1), b and d glutamine synthetase activity (△OD g^− 1 protein h^− 1), e and g glutamic oxaloacetic transaminase activity (µmol g^− 1 30 min^− 1), f and h glutamate pyruvate transaminase activity (µmol g^− 1 30 min^− 1). Different lowercase letters indicate significant difference at P<0.05. CK, LG, MG and HG refer to no grazing, light grazing, moderate grazing and heavy grazing, respectively