青藏高原东缘高寒草甸不同功能群植物氮磷化学计量特征研究

Characteristics of Nitrogen and Phosphorus Stoichiometry of Plants in Different Functional Groups on Alpine Meadow in the Eastern Edge of Tibetan Plateau

通过对青藏高原高寒草甸坡向梯度上植物样地的调查,研究了不同功能群(禾草、非豆科杂草及豆科)植物之间N∶P化学计量特征及比叶面积的差异,并结合分析土壤因子,探讨了它们与土壤温度、水分及养分之间的关系。研究结果显示:豆科植物的氮含量及氮磷比在不同坡向均高于其它功能群,禾草的氮含量、磷含量及比叶面积在不同坡向上均显著低于其它功能群,杂草的氮磷比在阴坡-阳坡梯度上有一个明显的上升趋势,根据氮磷比值判断,杂草在阴坡倾向于N限制,在阳坡则倾向于P限制,而豆科植物在不同坡向均倾向于P限制,禾草介于二者之间。相关分析表明,坡向梯度上土壤全磷、含水量与植物叶片磷含量、比叶面积显著正相关,与叶片氮磷比显著负相关;土壤温度、pH与植物叶片磷含量、比叶面积显著负相关,与植物叶片氮磷比显著正相关。土壤含水量、土壤温度与土壤全磷含量对不同坡向功能群氮磷化学计量特征的影响起着主要作用。

Plants along slope aspect gradients of alpine meadow were investigated, N. P stoichiometry and specific leaf area （SLA） of plants among different functional groups （grasses, forbs and legumes） were studied, soil factors were analyzed, and the relationships between plant N ： P stoichiometry and soil temperature, moisture and nutrients were explored. The results showed that the nitrogen content and N ： P ratio of legumes were higher than other functional groups in different slope aspects, nitrogen content, phosphorus content and SLA of grasses were lower than other functional groups, N ： P ratio of forbs were increased significantly along north-facing slope to south-facing slope gradients. According to N ： P ratio, forbs tended to N limitation in north-facing slopes, tended to P limitation in south-facing slope, and legumes plants tended to P limit in different slope aspects, grasses were in medium. Correlation analysis showed that soil phosphorus and water content were significantly positively correlated with plant leaf phosphorus content and SLA, they were significantly negatively correlated with leaf N ： P ratio; soil temperature and pH were significantly negatively correlated with plant leaf phosphorus content and SLA, while they were positively correlated with N ： P ratio in leaf. Soil water content, soil temperature and soil phos- phorus content were the main factors affecting characteristics of nitrogen and phosphorus stoichiometry among functional groups.