Read Jennifer, Sanson Gordon D
School of Biological Sciences, Monash University, Victoria 3800, Australia.
New Phytol. 2003 Oct;160(1):81-99. doi: 10.1046/j.1469-8137.2003.00855.x.
• Although sclerophylly is defined by textural properties, its adaptive significance has been debated without a strong base of mechanical data. We measured a wide range of mechanical properties across a diverse range of species and leaf forms, including highly scleromorphic leaves, and compared these with sclerophylly indices to determine the mechanical properties of sclerophylls. • Fracture and flexure tests were used to determine leaf strength, toughness (work to fracture) and flexural stiffness ('structural' properties), and specific strength, specific toughness and Young's modulus of elasticity ('material' properties, i.e. normalized per unit leaf thickness). • Leaves varied considerably in all properties tested, and in the way they combined various 'structural' and 'material' properties. However, on average, highly scleromorphic leaves were stronger, tougher and stiffer than soft leaves. 'Structural' properties correlated more strongly with sclerophylly than 'material' properties, and the ratio of stiffness to strength and toughness increased in sclerophyllous species. • Of the structural properties, strength, toughness and flexural stiffness each made substantial independent contributions to the variation in sclerophylly indices, but the best individual explanators were flexural stiffness and strength, with the best predictive model being a combination of these two properties. This model should now be tested on leaves from contrasting environments.
• 尽管硬叶植物是由质地特性定义的，但其适应意义一直存在争议，且缺乏有力的力学数据基础。我们测量了多种物种和叶形（包括高度硬叶形态的叶子）的广泛力学性能，并将这些性能与硬叶植物指数进行比较，以确定硬叶植物的力学性能。
• 采用断裂和弯曲试验来测定叶片强度、韧性（断裂功）和弯曲刚度（“结构”特性），以及比强度、比韧性和杨氏弹性模量（“材料”特性，即每单位叶片厚度的归一化值）。
• 在所测试的所有性能方面，叶片差异很大，且在组合各种“结构”和“材料”特性的方式上也存在差异。然而，平均而言，高度硬叶形态的叶子比柔软的叶子更强、更坚韧且更硬。“结构”特性与硬叶植物的相关性比“材料”特性更强，并且硬叶植物物种的刚度与强度和韧性之比增加。
• 在结构特性中，强度、韧性和弯曲刚度各自对硬叶植物指数的变化都有显著的独立贡献，但最佳的个体解释因素是弯曲刚度和强度，最佳预测模型是这两种特性的组合。现在应该在来自不同环境的叶片上对该模型进行测试。
