氮添加和刈割对内蒙古典型草原植被碳氮库的影响

外源氮输入和割草是影响草地植被碳、氮库的两个重要因素，外源氮能否补充因割草带走的养分使得植被和土壤碳、氮库保持平衡尚不明确。为了解刈割和氮输入对植被碳、氮库的影响，本研究在内蒙古典型草原设置刈割和5水平氮添加交互试验。结果表明：刈割显著降低了植物生物量和碳、氮库(P < 0.05)，氮添加可促进刈割后的生长补偿；氮添加显著提高了植物生物量及碳、氮库(P < 0.05)，同时改变了地上、地下部分生物量和碳、氮库的分配；不同水平的氮添加影响植被碳、氮库，当氮添加水平为10 g·m^-2·a^-1时，植被碳、氮库最高。以上结果表明，刈割与10 g· m^-2·a^-1氮输入相结合可支持内蒙古典型草原的可持续利用。

Effects of Nitrogen Addition and Mowing on Plant Carbon and Nitrogen Pools in Typical Grassland of Inner Mongolia

Exogenous nitrogen input and mowing are two important factors affecting the carbon and nitrogen pools of grassland plant.It is not clear whether exogenous nitrogen can supplement the nutrients taken away by mowing to maintain the balance of carbon and nitrogen pools of plant and soil.In order to understand the effects of mowing and nitrogen input on plant carbon and nitrogen pools,an interactive experiment between mowing and 5 levels of nitrogen addition was conducted in a typical steppe of Inner Mongolia.The results showed:mowing significantly reduced plant biomass and the pools of carbon and nitrogen(P<0.05),and nitrogen addition promoted the growth compensation after mowing;Nitrogen supplementation significantly increased plant biomass,carbon and nitrogen pools(P<0.05),and changed the allocation of biomass and the pools of carbon and nitrogen in aboveground and underground parts;Different levels of nitrogen addition affected the carbon and nitrogen pools of plant.When the nitrogen addition level was 10 g·m^-2·a^-1,the carbon and nitrogen pools of plant were the highest.The results showed that the combination of mowing and nitrogen input of 10 g·m^-2·a^-1 could support the sustainable utilization of typical steppe in Inner Mongolia.