氮素和水分添加对荒漠草原短花针茅氮磷特征的影响

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。%Knowledge of herbage nitrogen (N)and phosphorus (P)in plants is fundamental to the study of ab-sorption and utilization of nutrients by the plants.In order to better understand limiting factors and plant adap-tion 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 ad-dition (WD),nitrogen and water addition (NWD)and control (CK)with five replicates in a free grazed pad-dock in a S .breviflora desert steppe,Inner Mongolia.The S .breviflora leaf N and P concentrations and their stoichiometry under different treatments were analyzed.It was found that S .breviflora enhanced adaptability to barren habitats by increasing leaf N content.Uptake of N by S .breviflora was limited by low soil N and wa-ter 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 influ-enced 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.