【摘要】 试验研究了６种放牧强度对牦牛生长及草地第二性生产力的影响。结果表明，放牧强度对牦牛日增重有明显影响（ｐ＜０．０１），日增重以０．２４牦牛单位／ｈｍ￣２处理组最高，达７０７．９ｇ，随着放牧强度的增大，牦牛日增重明显降低（ｒ＝－０．９２）。其中，放牧强度对１岁牦牛影响最大（Ｐ＜０．０１），２岁牦牛次之（Ｐ＜０．０５），３岁牦牛再次（Ｐ＜０．０５）。试验全期（６月９日～９月２７日）当放牧强度低于１．２牦牛单位／ｈｍ￣２时，增大放牧强度，草地第二性生产力明显提高（ｐ＜０．０１），当放牧强度高于１．２牦牛单位／ｈｍ￣２时，增大放牧强度，草地第二性生产力则呈下降趋势，但试验后期（７月１３日～９月２７日）草地生产能力则以０．７２牦牛单位／ｈｍ￣２组为最高。更多还原

【Abstract】 The effect of 6 grazing intensities on growth of yak and the secondary productivity of sward was studi-ed.The result showed that grazing in tensity significantly affect the daily weight increase of yak(P<0.01),which is the largest of0.2 4 yak unit per hm2,to 707.9g,and with the intensity increase,theweight obviously decrease (r=-0.92).The effect order on yak is 1 year old the biggest(P< 0.01),2years old the secondary(P<0. 05),3 years old the latest(P<0.05).During the whole test period ,whengrazing intensity is lower than 1.2 yak unit per hm2,grazing intensity increases,the secondary productivi-ty of sward increases significantly(P<0.01 ).But conversely,the secondary productivity of grassland willdecrease。In late period,the productivity of grassland is the highest of 0.72 yak unit per hm2.更多还原