【摘要】 植物氮(N)、磷(P)含量特征为研究植物的养分利用状况提供了重要的手段。为判断草地生态系统植被限制性元素及对环境的适应策略,在短花针茅荒漠草原的自由放牧区进行了N和水分添加试验,研究在N和水分添加条件下优势植物短花针茅叶的N、P含量及其化学计量特征。通过对N添加、水添加和N水同时添加3个处理的测定表明,短花针茅通过提高叶N含量来增强对贫瘠生境的适应能力。N和水分是影响短花针茅N吸收的限制因子。短花针茅叶N、P含量及N∶P对N添加和水添加的响应在成熟期较枯萎期敏感;N对成熟期叶的N、P含量、N∶P以及枯萎期的N∶P有显著影响,而水分仅对成熟期叶的N、P含量有影响。更多还原

【Abstract】 Knowledge of herbage nitrogen(N)and phosphorus(P)in plants is fundamental to the study of absorption and utilization of nutrients by the plants.In order to better understand limiting factors and plant adaption strategies to environmental factors in the grassland ecosystem,water and N enhancement experiments were carried out in a Stipa breviflora steppe.Four treatments were set up:nitrogen addition(ND),water addition(WD),nitrogen and water addition(NWD)and control(CK)with five replicates in a free grazed paddock in a S.brevifloradesert steppe,Inner Mongolia.The S.brevifloraleaf N and P concentrations and their stoichiometry under different treatments were analyzed.It was found that S.brevifloraenhanced adaptability to barren habitats by increasing leaf N content.Uptake of N by S.breviflora was limited by low soil N and water contents.The absolute leaf N and P contents and the N∶P ratio were more sensitive to the environmental addition of N and water in mid season than in late season.The availability of environmental N greatly influenced the leaf N and P contents and N∶P ratio in mid season and the N∶P ratio in late season when plants were withering.However,the availability of water only affected the leaf N and P content in mid season and not in late season.更多还原