放牧强度对高寒草地产草量及羊体质量增加的影响

以托云牧场高寒草地为研究对象，通过设置3个放牧样地，一个对照样地，研究不同强度放牧对草地地上生物量的影响以及在不同放牧压力下羊体质量增加的效果。结果表明，1）托云牧场是以银穗草（Leucopoa albida）、羊茅（Festuca arioides）、点地梅（Androsace umbellata）和棘豆（Oxytropis falcatae）为优势种的高山草地；2）高寒草地地上生物量较低，禁牧区7月地上生物量（干物质）仅830 kg·hm-2;3）放牧活动对地上生物量有较大影响，重度放牧能显著降低牧场地上生物量；4）以羊体质量增加值为评价指标，该高寒牧场在载畜量为1.05羊单位·hm-2时能获得较好的体质量增加效果。

Effects of different grazing intensities on aboveground biomass and body weight of sheep on Alpine grasslands

In the present study, the impact of grazing on the aboveground biomass of alpine grasslands and the gaining effect of sheep were investigated.Tuoyun pasture was selected as a study area. Three grazing plots were set as treatment plots and a natural growth grasslands was set as the control plot. The results showed that 1) Tuoyun pasture is an alpine meadow with Leucopoa albida, Fescue arioides, Androsace umbellata and Oxytropis falcatae as the dominant species; 2) aboveground biomass of alpine grassland was very low, even in the prohibited graze area in July, and the aboveground biomass (dry matter) was merely 830 kg·ha-1; 3) grazing activities have a great impact on the aboveground biomass of the pasture, and heavy grazing can significantly reduce the aboveground biomass; 4) using the effect of liveweight gain as an evaluation index, a better weight gain was obtained under the stocking rates of 1 sheep unit (i.e. an ewe and a lamb) per hectare in this alpine pasture.