中文摘要：

以高寒草甸金露梅灌丛为研究对象,通过添加不同量的氮磷复合肥NH4H2PO4（0、40、80、120 g·m-2）,测定了花苜蓿（Medicago ruthenica Linn.）、异叶米口袋（Gueldenstaedtia diversifolia Maxim）、甘肃棘豆（Oxytropis kansuensis Bunge.）的地上生物量、叶片氮磷含量和土壤氮磷含量,探讨了添加氮磷之后豆科植物的叶片氮磷含量、N：P比值在处理间和种间的差异以及它们与土壤养分之间的关系.结果表明,添加氮磷使花苜蓿和异叶米口袋叶片中的磷含量和N：P比值发生显著变化,而对叶片氦含量的影响不显著.氮磷的添加对甘肃棘豆的氮磷含量无显著影响.就总的豆科植物而言,不论种内还是种间,平均可变性都是磷变化最大,氮变化最小,N：P比值居中.植物叶片的氮磷含量以及N：P比值与土壤速效氮磷没有显著相关性.比较不同处理下的数据可知,添加氮磷复合肥主要增加了豆科植物对磷素的养分吸收.三个物种对氮磷的吸收能力不同,叶片的氮磷含量比N：P比值更能反映植物对氮磷的吸收利用情况.一次性施用氮磷复合肥不能提高第二年的氮供应能力,但是会提高土壤的有效磷供应.为保护豆科牧草的产量,对于金露梅灌丛草地施用磷酸二氢铵的量不应超过80 g·m-2.

英文摘要：

We examined how nitrogen（N） and phosphorus（P） concentrations, and N： P ratio in legumes varied among different species and fertilizer additions, and how they were related to nutrient availability in soil. We analyzed data from field studies in Potentilla fruticosa shrubs in alpine meadow adopting fertilization experiments with legumes. The results showed that adding N and P to Medicago ruthenica Linn. and Gueldenstaedtia diversifolia Maxim. increased P concentration and decreased N： P ratio, but had little effect on N concentration in leaves. N and P addition had no significant effect on N and P concentrations of Oxytropis kansuensis Bunge. P concentration was more variable than N concentration, while the variation in N： P rati, was intermediate. N concentration varied more significantly among species than among treatments, whereas P concentration and N：P ratio varied more significantly among treatments than among species. Nutrient concentration and N：P ratio in the vegetation were poorly correlated with available N and P in soil. This study suggests that the responses of individual plant species to fertilization can not be predicted from their N： P ratios but from their N and P concentrations. One-time application of nitrogen and phosphorus fertilizer can not effectively raise nitrogen supply in the second year, but it can increase the supply of soil phosphorus. In addition, in order to protect the legumes, NH4H：PO4 should not be applied over 80 g· m^2 in Potentillafruticosa shrubs