【摘要】 放牧是草原牧区常见的人类活动,多年放牧对草原植被及土壤的碳过程产生较大的影响.本研究采集不同类型草原多年放牧前后植被及土壤样品,对室内碳同位素进行分析,研究了不同草原生态系统Δ¹³C（碳同位素分馏值）差异及其影响因素.结果表明:放牧强度对植被Δ¹³C值的影响显著,0～5 cm表层土壤Δ¹³C值在放牧前后变化显著,而对深层土壤（>5 cm）影响不显著.多年放牧后大部分植被Δ¹³C值显著升高,高海拔地区升高的幅度较大.可见,放牧行为对不同草地生态系统类型、不同土壤深度以及不同海拔生态系统碳过程产生的影响差异显著.针对不同类型的草原,放牧应采取多样化的管理方式.更多还原

【Abstract】 Grazing is a common human activity on grassland region. Long-term grazing exerts great effects on ecosystem carbon cycling. In this study,we collected leaf and soil samples from different grassland types across the growing season,separately from un-grazed（ UG） and overgrazed（ OG）plots. By analyzing the carbon isotope values of samples in laboratory,this study revealed the divergent Δ¹³C value（ carbon isotope discriminative value） among different grassland ecosystems,as well as its influencing factors. The results showed that Δ¹³C value of soil at 0-5 cm significantly differed between UG and OG,but no difference at deeper layers（ > 5 cm）. The grazing intensity had significant influence on the Δ¹³C value of vegetation leaves. After long-term grazing,most vegetation showed a significant increase in Δ¹³C value,especially in high altitude areas. In conclusion,grazing have significantly divergent impacts on the carbon processes under different grassland ecosystems,soil depths and altitudes. Therefore,a variety of grazing management strategies should be adopted for various grassland ecosystems.更多还原