中文摘要：

植物生态化学计量学特征的地理学分布规律及其影响因素的研究是生态学研究的热点问题之一。以贺兰山西坡不同海拔高度7个群落为对象,研究群落物种多样性与植物叶片碳（C）∶氮（N）∶磷（P）计量特征的关系。结果表明：贺兰山低海拔区域,植物群落物种丰富度与群落植物叶片N∶P及其变异系数间无显著相关关系,没有支持＂群落植物叶片N∶P介于14～16时,群落植物丰富度最高;N∶P〈14或N∶P〉16时,群落植物丰富度均较少＂的模型,以及＂群落植物丰富度与群落植物叶片N∶P变异系数正相关＂的假设。其原因在于所调查样地群落植物丰富度均较低,且各样地物种丰富度相对集中,梯度较小（9～16种）。

英文摘要：

In recent years, the geographic variation in the plant stoichiometry has become as the center of stud- ying the structure and function of ecosystems with global climate change. This resarch explored the relationship between the biodiversity and the foliar stoichiometry （ C, N and P contents） in 7 different plant communities at different altitudes on the western slope of the Helan Mountain. The results showed that the species richness in plant comunity was decreased with the increase of elevation in low-altitude areas in the Helan Mountain, and there was no significant correlation between the species richness in plant community and the foliar stoichiometry （C, N and P contents and stoichiometric ratios and coefficients of variation of these indicators） in the Helan Mountain, which did not surpport the viewpoint that the value of species richness was higher when the foliar N： P mass ratio varied in a range of 14 - 16 than that when the foliar N： P mass ratio was higher than 14 or lower than 16, and the hypothesis that there was a positive correlation between the species richness and the variance of foliar mass ratio was surpported neither. Such results may be caused by the slight change of plant species richness in our research （9 - 16 plant species）.