【摘要】 以贝加尔针茅草原为研究对象,设置N0(0kg N·hm-2)、N30(30kg N·hm-2)、N50(50kg N·hm-2)、N100(100kg N·hm-2)、N150(150kg N·hm-2)5个氮添加水平,研究不同氮添加水平对6种植物叶C、N、P计量特征和土壤C、N、P计量特征的影响,分析植物计量特征与土壤计量特征的相关性,为深入理解N沉降增加对草原群落结构的影响提供基础数据。结果表明,自然条件下,6种植物叶C、N、P含量和计量特征存在显著的差异,表现为扁蓿豆叶C、N、P含量和叶N∶P最高,贝加尔针茅叶N、P含量最低,线叶菊叶C含量最低。氮添加提高了除扁蓿豆以外其他5种植物叶N含量,叶C∶P和叶N∶P,降低了叶P含量和叶C∶N,而叶C含量无一致变化趋势。氮添加提高了土壤有机碳含量、土壤N∶P,对土壤全氮含量和土壤C∶N无显著性影响。羊草、羽茅、线叶菊和草地麻花头叶N含量与土壤有机碳、土壤N∶P呈显著正相关,贝加尔针茅、羊草、羽茅和草地麻花头叶N∶P与土壤有机碳、土壤C∶P呈显著正相关。综合分析表明,土壤有机碳、土壤N∶P和土壤C∶P是影响6种植物叶C、N、P含量和计量特征的主要影响因素,但不同植物对氮添加的响应不同,意味着长期氮添加可能会改变贝加尔针茅草原生态系统的结构。更多还原

【Abstract】 The objective of this study was to investigate the effects of nitrogen addition on soil and plant carbon(C),nitrogen(N),phosphorus(P)and C∶N∶P ecological stoichiometric characteristics in the Stipa baicalensis grassland of Inner Mongolia,China.The plant study focused on six dominant species:S.baicalensis,Leymus chinensis,Achnatherum sibiricum,Filifolium sibiricum,Melissitus ruthenicaand Serratula yamatsutanna.A randomized block design experiment was conducted,with six blocks of five treatments each:N0(0 kg N·ha-1),N30(30 kg N·ha-1),N50(50 kg N·ha-1),N100(100 kg N·ha-1)and N150(150 kg N·ha-1).The results showed that there were significant differences in leaf C,N and P contents and in the stoichiometric characteristics of the six species under natural conditions.Pocockia ruthenica had the highest leaf C,N,and P contents and leaf N∶P,while S.baicalensis had the lowest leaf N and P contents and F.sibiricumhad the lowest leaf C content.Leaf C contents did not respond to nitrogen addition in all the six plant species.Leaf N contents,leaf C∶P and leaf N∶P significantly increased but leaf P contents and leaf C∶N decreased with nitrogen addition in five of the species,other than M.ruthenica,which did not respond to nitrogen addition.Soil organic carbon and soil N∶P increased significantly,while soil total nitrogen and soil C∶N showed no significant responses to nitrogen addition.The individual leaf N contents of L.chinensis,A.sibiricum,F.sibiricumand S.yamatsutanna were positively correlated with soil organic carbon and soil N∶P.The leaf N∶P of S.baicalensis,L.chinensis,A.sibiricum and S.yamatsutanna were positively correlated with soil organic carbon and soil N∶P.In conclusion,soil organic carbon,soil N∶P and soil C∶P were the main factors that affected leaf C,N,P contents and the C∶N∶P ecological stoichiometric characteristics of the six plant species,but different species had different responses to nitrogen addition,meaning that long-term nitrogen addition may change the structure of the S.baicalensis grassland ecosystem.更多还原