In order to further understand of the plants response and adaptation mechanism to nitrogen addition in primary and secondary tropical montane rain forests, the authors conducted a nitrogen addition experiment in the primary and secondary forests in Mt. Jianfengling respectively, setting three nitrogen addition treatments (0, 50 and 100 kg N/(ha·yr)) in each forest, to explore the effects of enhanced nitrogen addition on amino acid content in leaves of understory shrubs. The results showed that when no nitrogen was added, the contents of total amino acids and hydrolyzed amino acids in primary forest and secondary forest were not significant, while the content of free amino acids in primary forest was significantly higher than that in secondary forest. When middle nitrogen was added, the response of leaf amino acid content of understory plants in secondary forests was higher than that in primary forests. When high nitrogen was added, there was no significant difference in the response of hydrolyzed amino acids of understory shrubs in primary forest and secondary forest, but the response of free amino acids in understory shrubs in primary forests was higher than that in secondary forests. 

为了深入地了解热带山地雨林原始林与次生林叶氨基酸对氮添加的响应和适应机制, 以海南尖峰岭热带山地雨林原始林和次生林的林下常见植物为研究对象, 通过设置对照CK (0 kg N/(ha·a))、中氮添加M (50 kg N/(ha·a))和高氮添加H (100 kg N/(ha·a)) 3种氮添加处理的实验, 探究氮添加对林下灌木叶片氨基酸含量的影响。实验结果表明, 无氮添加时, 原始林与次生林的总氨基酸含量和水解氨基酸含量无显著差异, 原始林游离氨基酸总含量显著高于次生林; 中氮添加时, 次生林林下灌木叶氨基酸含量的响应程度高于原始林; 高氮添加时, 次生林与原始林林下灌木水解氨基酸的响应程度无显著差异, 原始林林下灌木游离氨基酸的响应程度高于次生林。