植物叶片水力与经济性状权衡关系的研究进展

Trade-offs between plant leaf hydraulic and economic traits

叶片既是植物光合产物形成的主要场所,又是整株植物的水力瓶颈、应对灾难性水力失调的安全阀门,是植物碳水耦合权衡的重要器官。叶经济型谱反映了叶片经济性状"投资-收益"的权衡,为验证植物进化过程中形成的物种对策提供了适用的理论框架。叶片水力性状变化会影响叶片经济性状及植物存活和生长。因此,探索植物叶片水力与经济性状的权衡关系,对建立植物碳-水耦合模型、揭示植物水-碳投资机理、扩展植物性状型谱等均有重要意义。该文首先综述了叶片水力性状、经济性状及两者之间的权衡关系,分析了叶片导水率与水力脆弱性、失膨点水势、水容、安全阈值等水力性状以及与叶片的形态、结构和气体交换功能性状之间的关系。然后,从叶片形态、解剖和叶脉网络结构以及气孔功能方面探讨了叶片水力性状与经济性状的调节机制。最后,提出今后应加强三方面的研究:(1)探索建立植物根-茎-叶水力输导系统的碳-氮-水资源的整株经济型谱,以揭示植物功能结构耦合、高效固碳用水的生理生态学机制;(2)探索叶片水力安全、水力效率和固碳效率之间的普适性权衡关系,以深入理解抗旱植物叶片构建的生物物理结构与生理代谢的关系;(3)探索个体水平碳水代谢关系、水分运输与生长速率的耦合,为代谢推演理论和植物群落尺度预测提供基础。

Leaf is the most important organ for carbon-water coupling of a plant because it is the primary medium for photosynthesis. It also acts as the hydraulic bottleneck and safety valve against hydraulic catastrophic dysfunctions. The leaf economics spectrum, which reflects the balance between investments and returns of leaf economic traits, provides a useful framework for examining species strategies as shaped by their evolutionary history. Changes in leaf hydraulic traits will influence leaf economic traits as well as plant survival and growth. Exploring trade-offs between leaf hydraulic and economic traits is thus of significance for modeling carbon-water relations, understanding the mechanisms of water/carbon investments, and extending the leaf economic spectrum. In this review, we first examined the trade-offs between leaf hydraulic and economic traits. Specially, we analyzed the relationships between leaf hydraulic conductivity and hydraulic vulnerability, water potential at the turgor loss point, water capacitance, safety margin, and leaf morphological, structural and functional traits. We then discussed potential mechanisms regulating leaf hydraulic and economic traits from leaf morphology, anatomy, venation, and stomatal functions. Finally, we proposed future research to：（1） develop an integrated whole-plant economics spectrum, including carbon-nitrogen-water resources and root-stem-leaf hydraulic transport system that will help revealing ecophysiological mechanisms of plant structure-functional coupling, carbon sequestration and water use;（2） explore a generalized trade-offs among leaf hydraulic safety, hydraulic efficiency and carbon fixation efficiency to advance our understanding of the relationships between biophysical structure and physiological metabolism in plant leaf construction under drought stress; and（3） explore the carbon-water metabolic relationship and coupling of water transport and growth rate for the metabolic theory and predictions at community scale.