中文摘要：

本文运用开路式土壤碳通量测量系统-LI-8100在短花针茅（Stipa breviflora Griseb）荒漠草原测定4组不同载畜率的土壤呼吸速率动态,并用土钻法测定了植物地下累积生物量,埋根袋法测定了根系净生长量。目的是比较不同载畜率对土壤呼吸、植物地下累积生物量和根系净生长量的影响,并探讨生长季土壤呼吸、8月份土壤呼吸对植物地下累积生物量、根系净生长量的响应。结果表明：随着载畜率增加,植物地下累积生物量减少,根系生长减缓,但对土壤呼吸无显著影响;生长季土壤呼吸与植物地下累积生物量呈线性正相关,8月份土壤呼吸值随根系净生长量增大而增大。土壤呼吸受植物地下生物量影响显著,生长季初期,新根刚开始生长,土壤呼吸大部分来自老根,到了生长旺季,新根生物量增多,土壤呼吸速率加快,新根主导了土壤呼吸。

英文摘要：

Li-8100 open circuit soil carbon flux measuring system was used to measure the soil respiration rate of four stocking rates during growing periods （May-October） in this study. Meanwhile, soil cores were collected to measure cumulative plant belowground biomass and net root biomass at the end of August in order to compare the effect of different stocking rates on soil respiration, cumulative plant belowground biomass and net root biomass, to understand the relationships between soil respiration in growing season, soil respiration in August and cumulative plant belowground biomass, net root biomass, respectively. The results showed as follows： cumulative plant belowground biomass and root growth reduced with the increase of stocking rate, there was no significant effect on soil respiration among different stocking rates. Soil respiration during growing season was significantly positive linear correlation with cumulative plant belowground biomass, and soil respiration in August was significantly positive linear correlation with net root biomass. Soil respiration was significantly influenced by plant belowground biomass. New roots started growing at the beginning of growing season ; and soil respiration mostly depended on old roots. When new root biomass increased, soil respiration rate increased rapidly and reached the maximum value in summer, they determined the major soil respiration at this period.