【摘要】 以松嫩草地的优势种——羊草(Leymus chinensis)为研究对象，对添加N和P条件下羊草-土壤-根际微生物系统中不同元素及其化学计量的变化趋势进行了实验观测与分析.结果表明：(1)在分别添加N和P及N和P共同添加(N+P)的条件下，羊草(叶根)、土壤以及根际微生物的C,N,P含量及比值均产生了不同的变化，N添加增加了土壤有机碳和N含量，P和N+P的添加增加了土壤P含量；N添加增加了叶C和根N含量并降低了叶P含量，P添加降低了叶N含量，增加了叶、根P含量，N+P添加增加了叶C和P含量以及根N含量；N和P及N+P添加降低了根际微生物C和N含量，而N+P添加增加了微生物P含量.(2)羊草生长受到N和P的共同限制，其中N限制更强.N添加虽能缓解N限制产生的影响，但会将植物生长所受的限制进一步转变为P限制；而P添加则会加剧草地受N限制的程度，破坏植物C,N,P化学计量的平衡.(3)N和P添加可导致根际微生物的C限制，减少了根际微生物的生物量，从而使根际微生物在与植物的养分竞争中处于劣势地位.(4)N和P添加条件下的根际微生态系统中，与植物根相比，土壤和根际微生物均与植物叶的化学计量关系更紧密.更多还原

【Abstract】 The stoichiometric characteristics of grassland are an important index to evaluate grassland quality, but the response of plant-soil-microbe components and their stoichiometric characteristics to N and P input in grassland ecosystem are not clear.This study takes Leymus chinensis,the dominant species in Songnen grassland as the research object, and carried out experimental observation and analysis on the changing trends of different elements and their stoichiometry in L.chinensis,soil and rhizosphere microbe with N and P additions.The results showed that(1) The addition of N,P and N+P altered the contents and ratios of C,N,P of L.chinensis(leaves, roots),soil and rhizosphere microbe.N addition increased soil SOC and N content, P and N+P addition increased soil P content; N addition increased leaf C and root N content and decreased leaf P content, P addition increased leaf N,P content and root P content, N+P addition increased leaf C,P content and root N content; N,P and N+P decreased rhizosphere microbe C and N content, while N+P addition increased microbe P content.(2) The growth of L.chinensis was limited by N and P,and was more limited by N.Although N addition can alleviate the effect of N limitation, it caused plant growth to be limited by P.P addition aggravated the degree of N limitation on grassland and destroyed the balance of C/N/P stoichiometry.(3) The addition of N and P can lead to the C limitation of rhizosphere microbe, and reduce the biomass of rhizosphere microbe, so that the rhizosphere microbe is in a disadvantaged position in the nutrient competition with plants.(4) In the rhizosphere micro-ecosystem with N and P addition, the soil and rhizosphere microbe were more closely related to the stoichiometry of plant leaves than plant roots.But in general, the stoichiometric relationship between plant-microbe and soil-microbe tended to be decoupled, this led to the imbalance of C,N and P stoichiometry of each component in plant-soil-microbial system and reduced the stability of the rhizosphere micro-ecosystem.更多还原