Yang Mei, Sun Dan, Wang Xiaoyin, Zhu Shidan, Goodale Uromi Manage
Guangxi Key Laboratory of Forestry Ecology and Conservation, College of Forestry, Guangxi University, Nanning 530004, China.
Nanning Institute of Tropical Botany, Nanning Botanical Garden, Nanning 530029, China.
Plants (Basel). 2025 Apr 8;14(8):1161. doi: 10.3390/plants14081161.
The leaf economic spectrum framework explains how plants optimize leaf traits for productivity, distribution, and stress tolerance. Orchids in Southwestern China's karst forests, especially lithophytic species, are challenged by prolonged drought and limited light availability. This study investigated different leaf strategies between lithophytic and terrestrial orchids under the harsh karst environment. We measured key leaf traits, including photosynthesis, structure, biomechanics, nitrogen allocation, and water relations, in twenty-two lithophytic and six terrestrial orchids in a subtropical karst forest. After accounting for phylogenetic influences, we found that lithophytic orchids had a higher leaf mass per area, cuticle thickness, and biomechanical resistance () but a lower maximum photosynthetic rate (A), nitrogen allocation to photosynthesis (N), and saturated water content (SWC) than terrestrial orchids. These results suggest that lithophytic orchids prioritize structural investment and stress tolerance over photosynthetic efficiency. Across species, N correlated positively with A and negatively with , highlighting nitrogen allocation as a key mechanism in leaf cost-benefit strategies. Additionally, SWC emerged as a critical driver of variation in multiple traits, supporting its integration into the leaf economic spectrum for orchids in karst ecosystems. This study offers new insights into orchid adaptation in subtropical karst environments, with implications for plant resilience under changing climates.
叶经济谱框架解释了植物如何优化叶片性状以提高生产力、分布范围和胁迫耐受性。中国西南部喀斯特森林中的兰花，尤其是附生植物，面临着长期干旱和光照有限的挑战。本研究调查了在恶劣的喀斯特环境下附生兰花和地生兰花之间不同的叶片策略。我们测量了亚热带喀斯特森林中22种附生兰花和6种地生兰花的关键叶片性状，包括光合作用、结构、生物力学、氮分配和水分关系。在考虑系统发育影响后，我们发现附生兰花比地生兰花具有更高的单位面积叶质量、角质层厚度和生物力学抗性，但最大光合速率（A）、光合氮分配（N）和饱和含水量（SWC）较低。这些结果表明，附生兰花在光合效率之上优先考虑结构投资和胁迫耐受性。在所有物种中，N与A呈正相关，与呈负相关，突出了氮分配作为叶片成本效益策略中的关键机制。此外，SWC成为多个性状变异的关键驱动因素，支持将其纳入喀斯特生态系统兰花的叶经济谱。本研究为亚热带喀斯特环境中的兰花适应性提供了新见解，对气候变化下的植物恢复力具有启示意义。
