Abstract: Rest grazing in the greenup period is the most economical and feasible measure in the restoration of degraded grassland and has been widely popularized and applied,In order to explore the effects of rest grazing on plant growth and photosynthetic characteristics of alpine meadow,this study started the rest grazing experiment during the regreen period from 2015 in Qilian Mountain area of Qinghai province. In 2018 and 2019,investigation and determination of test sample to plant community characteristics and photosynthetic physiological indexes. The results showed that,after 4 years of resting grazing,the total grass coverage,the height of the dominant herbage Elymus nutans Griseb.,the aboveground biomass and the underground biomass increased by 35%,777%,1140% and 217% respectively,and the chlorophyll-content and net photosynthetic rate increased by 172% and 146% respectively. There was no significant difference in total coverage,aboveground biomass,chlorophyll content and net photosynthetic rate between the 4th and 5th year of rest-grazing during greenup period. Therefore,we pointed that rest-grazing during greenup period could significantly enhance the hotosynthesis and respiration process of forage grass,then promote vegetation growth and recovery. And the vegetation become stable after years of rest grazing. These results provide fundamental basis for popularization and application of rest grazing during greenup period on the Tibet Plateau degraded grassland.

Key words: Alpine meadow, Rest grazing during greenup period, Quantitative character of vegetation, Photosynthetic characteristics, Respiration rate

摘要： 返青期休牧为退化草地恢复中最经济可行的措施且已得到了较广泛的推广和应用，为探索返青期休牧对高寒草地植物生长及光合特性的影响，本研究于2015年开始在青海省祁连山区进行返青期休牧试验，于2018年和2019年调查并测定试验样地植物群落特征和光合生理指标。结果表明：返青期休牧4年后，草地总盖度、优势种牧草垂穗披碱草（Elymus nutans）高度、地上生物量和地下生物量较未休牧分别提高了35%，777%，1140%和217%，垂穗披碱草叶绿素含量和净光合速率分别增加了172%和146%；草地总盖度、地上生物量和垂穗披碱草叶绿素含量及净光合速率在休牧第4年和休牧第5年之间差异不显著。因此，在高寒草地实施返青期休牧可提高优势牧草光合作用、促进退化草地植被的恢复，且退化草地植被在休牧一定年限后趋于稳定。本研究为青藏高原推广实施返青期休牧这一措施来恢复退化草地植被提供了理论基础。

关键词: 高寒草甸, 返青期休牧, 植被数量性状, 光合特性, 呼吸速率