SCION, 49 Sala Street, Rotorua 3010, New Zealand.
Am J Bot. 2009 May;96(5):885-96. doi: 10.3732/ajb.0800226.
Wind can alter plant growth and cause extensive, irreversible damage in forested areas. To better understand how to mitigate the effects of wind action, we investigated the sensitivity of tree aerodynamic behavior to the material and geometrical factors characterizing the aerial system. The mechanical response of a 35-yr-old maritime pine (Pinus pinaster, Pinaceae) submitted to static and dynamic wind loads is simulated with a finite element model. The branching structure is represented in three dimensions. Factor effects are evaluated using a fractional experimental design. Results show that material properties play only a limited role in tree dynamics. In contrast, small morphological variations can produce extreme behaviors such as either very little or nearly critical dissipation of stem oscillations. Slender trees are shown to be relatively more vulnerable to stem breakage than uprooting. Dynamic loading leads to deflections and forces up to 20% higher near the base of the tree than those calculated for a static loading of similar magnitude. Effects of branch geometry on dynamic amplification are substantial yet not linear. The flexibility of the aerial system is found to be critical to reducing the resistance to the airflow and thus to minimizing the risk of failure.
风可以改变植物的生长，并在森林地区造成广泛的、不可逆转的破坏。为了更好地了解如何减轻风的影响，我们研究了树木空气动力行为对表征空中系统的材料和几何因素的敏感性。使用有限元模型模拟了一棵 35 岁的地中海松树（Pinus pinaster，松科）对静态和动态风荷载的机械响应。分支结构以三维形式表示。使用分数实验设计评估因素效应。结果表明，材料特性在树木动力学中仅起有限作用。相比之下，小的形态变化会产生极端行为，例如树干振动的耗散要么非常小，要么几乎达到临界。与连根拔起相比，细长的树木更容易因树干断裂而受损。动态加载会导致树木底部的挠度和力比类似大小的静态加载计算值高出 20%。分支几何形状对动态放大的影响很大，但不是线性的。空中系统的灵活性对于减少对气流的阻力至关重要，从而最大限度地降低失效风险。
