Botanical composition, aboveground biomass and grazing behaviour of yak (Bos grunniens)in southern rangeland of Qinghai Province, China

摘要

Botanical composition and biomass of rangelands and grazing behaviour of yaks were investigated in two ranches (A and B) in Yushu State, Qinghai Province, China. Edible plant biomass was significantly smaller in A (42. 9 gDM/m~2) than B (109. 8 gDM/m~2) (P < 0.05). Dominant and subdominant species of plants in A were Ko-bresia capillifolia , Saussurea Stella , Stellera chamaejasme , Ligularia virgaurea , Poa poiphagorum , etc. , and those in B were K. pygmaea, K. humilis, Stipa aliena , Taraxacum mongolicum, etc. S. Stella is known to be unpalatable but was still grazed by yak cows in A but was rarely done in B. The grazing behaviour of yaks differed in the two ranches: the number of feeding stations in a patch was significantly greater (P < 0.01) and the bite number in a feeding station was significantly smaller (P < 0.001) in A than in B. Bite rate was slower in A than in B (P= 0.05). It is suggested that deterioration of rangeland by overgrazing might have been in progress and have been limiting nutritional intake and lowering productivity of yak in A as compared with B.