Abstract: This study was conducted in a meadow dominated by Leymus chinensis (Hulunbeir Grassland Ecosystem Research Station) during two consecutive years. To assess the impact of grazing intensity on plant aboveground biomass,belowground biomass and their distribution pattern,plant biomass of aboveground and belowground were measured under no grazing,light grazing,moderate grazing and heavy grazing,respectively. The results showed that the total aboveground biomass decreased when grazing intensity was increased,with the biomass of 238.14 g·m^-2 without grazing and 79.60 g·m^-2 under heavy grazing. However,the proportion of the biomass of forb was significantly increased when grazing intensity was increased,ranging from no grazing 35.93% to heavy grazing 97.66%. Total belowground biomass tended to decrease first and then increase along the grazing gradient under the moderate grazing. Furthermore,more belowground biomass was distributed to the topsoil,61.86% and 64.43% of total belowground biomass were distributed to 0~10 cm layer soil in 2013 and 2014,respectively,with the highest under light grazing. In general,grazing causes changes in the aboveground and underground biomass distribution of plant communities,and it is more reasonable to use the grassland with light or moderate grazing in this area.

Key words: Grazing intensity, Meadow grassland, Biomass distribution

摘要： 本研究以羊草（Leymus chinensis）草甸草原（基于呼伦贝尔草原生态系统国家野外科学观测研究站）为研究对象，通过测算2013年和2014年植物群落地上和地下生物量在不同放牧强度（不放牧、轻度放牧、中度放牧、重度放牧）下的变化，探究不同放牧强度对植物群落地上、地下生物量分布的影响。研究结果显示，群落地上生物量随放牧强度增加而减少，从不放牧的238.14 g·m^-2减少至重度放牧的79.60 g·m^-2；杂类草地上生物量所占比例增加，由不放牧的35.93%增加至重度放牧的97.66%。群落地下生物量随放牧强度增加呈先降低后增加的趋势，中度放牧时最小（2013年733.25 g·m^-2、2014年682.99 g·m^-2）；轻度放牧下，群落地下生物量在0~10 cm土层分布比例最大，2013年为61.86%，2014年为64.43%。综上可得出，放牧会引起植物群落地上、地下生物量分布发生变化，轻度或中度放牧利用该区域草地比较合理。

关键词: 放牧强度, 草甸草原, 生物量分布