Chen Fajun, Zhao Gaojuan, Shen Youxin, Zhu Hong, Li Zhenjiang, Tan Beilin
CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun 666303, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Plants (Basel). 2024 Sep 20;13(18):2626. doi: 10.3390/plants13182626.
Shading and water addition are essential management measures to improve seed germination and early seedling survival; however, little is known about their effects on leaf stoichiometry and nutrient status. We established 90 plant communities with shading and water addition gradients on a rocky hill; leaves of their dominant woody plant species were collected to measure elemental concentrations, and then, stoichiometric variation and nutrient status were analysed. The results showed that the overall effects of shading and water addition significantly altered the concentrations and ratios of nutrient elements; shading largely affected leaf K and P, while water addition mainly affected leaf N and P. The interactions between shading and water addition were significant for most species but disappeared at the community level. Consequently, the nutrient status in leaves was improved by promoting the concentrations and balances of nutrient elements. However, the responses to shading and water addition were marked by species-specific differences, with some plants forming a sensitive group and others distinguished by conservatism. Our findings show that management of the physical environment could improve nutrient element utilization in leaves and alleviate the nutrient limitations. For our site conditions, mild shading (25-35%) and adequate water addition (30 L·m) in the early stage of vegetation restoration is recommended to advance community assembly by improving nutrient physiology, directly diminishing the stress of water scarcity and excessive irradiation. These findings explore the underlying mechanisms of shading and water addition that could promote community development and provide guidance for restoration practice.
遮荫和补水是提高种子萌发率和幼苗早期成活率的重要管理措施；然而，关于它们对叶片化学计量和养分状况的影响却知之甚少。我们在一座岩石山上建立了90个具有遮荫和补水梯度的植物群落；采集其优势木本植物的叶片以测量元素浓度，然后分析化学计量变化和养分状况。结果表明，遮荫和补水的总体效应显著改变了营养元素的浓度和比例；遮荫主要影响叶片的钾和磷，而补水主要影响叶片的氮和磷。遮荫和补水之间的相互作用对大多数物种来说是显著的，但在群落水平上消失了。因此，通过促进营养元素的浓度和平衡，叶片中的养分状况得到了改善。然而，对遮荫和补水的反应存在物种特异性差异，一些植物形成了敏感组，而另一些则表现为保守型。我们的研究结果表明，对物理环境的管理可以提高叶片中营养元素的利用率，并缓解养分限制。就我们的场地条件而言，建议在植被恢复早期进行轻度遮荫（25-35%）和适量补水（30 L·m），以通过改善养分生理状况、直接减轻缺水和过度辐射的压力来推进群落组装。这些研究结果探索了遮荫和补水促进群落发展的潜在机制，并为恢复实践提供了指导。
