UMR EcoFoG, AgroParisTech, CIRAD, CNRS, INRAE, Université des Antilles, Université de Guyane, 97310 Kourou, France.
UMR AMAP, Université de Montpellier, CIRAD, CNRS, INRAE, IRD, Université de Montpellier, 34000 Montpellier, France.
J Exp Bot. 2021 Dec 4;72(22):7957-7969. doi: 10.1093/jxb/erab379.
The leaf size-stem size spectrum is one of the main dimensions of plant ecological strategies. Yet the anatomical, mechanical, and hydraulic implications of small versus large shoots are still poorly understood. We investigated 42 tropical rainforest tree species in French Guiana, with a wide range of leaf areas at the shoot level. We quantified the scaling of hydraulic and mechanical constraints with shoot size, estimated as the water potential difference (ΔΨ) and the bending angle (ΔΦ), respectively. We investigated how anatomical tissue area, flexural stiffness and xylem vascular architecture affect such scaling by deviating (or not) from theoretical isometry with shoot size variation. Vessel diameter and conductive path length were found to be allometrically related to shoot size, thereby explaining the independence between ΔΨ and shoot size. Leaf mass per area, stem length, and the modulus of elasticity were allometrically related to shoot size, explaining the independence between ΔΦ and shoot size. Our study also shows that the maintenance of both water supply and mechanical stability across the shoot size range are not in conflict.
叶片-茎大小谱是植物生态策略的主要维度之一。然而，小枝和大枝之间的解剖学、力学和水力学意义仍未被很好地理解。我们在法属圭亚那调查了 42 种热带雨林树种，它们在枝水平上具有广泛的叶片面积范围。我们量化了水力和机械约束与枝大小的比例关系，分别用水势差 (ΔΨ) 和弯曲角 (ΔΦ) 来表示。我们研究了解剖组织面积、弯曲刚度和木质部血管结构如何通过偏离（或不偏离）枝大小变化的理论等距性来影响这种比例关系。发现导管直径和导电路径长度与枝大小呈异速生长关系，从而解释了 ΔΨ 与枝大小的独立性。叶面积质量、茎长和弹性模量与枝大小呈异速生长关系，解释了 ΔΦ 与枝大小的独立性。我们的研究还表明，在整个枝大小范围内维持供水和机械稳定性并不矛盾。
